Hello All,

I have done a few searches on the subject but have not found a whole and complete answer.

Some months ago, i added water to my reservoir because i noticed it was low.

Just recently, 3 weeks or so, I started to notice some Boil over and out at the reservoir cap. It would boil out, and I'd add more water. It never over heated and the gauge in the cab never moved out of Normal Range- right on the "N"

Just recently, it had got considerably worse- it gauge beagan to reach the very bottom of the red on the thermostat gauge. But never reached the "RED" zone.

This weekend I replaced the thermostat and it still pegs up under the red of the gauge, but now it Falls a bit and stays hot it the upper rankings of "Normal Range" and still tends to boil over at the Cap.

I feel like replaceing the Thermostat has helped... but it doesn't actually seem to have done much.

The Volvo Mech i spoke with said that it was less likely the Fan or waterpump - because they either work or dont, and the fan works, and the water pump seems to be pumping- it certianly isn't leaking or making any noise.

So my question to you all is-

How would you diagnose the issue on the most limited of funds. I cant afford to take it to a shop. I need a viable way to rule things out so I can get to work- its my daily driver.

thank you all so much.

Gaz.
--
1979 245 DL

Ok Team-
I want to thank everyone for all their Help and input.

I am replying to myself, I know, But i wasn't sure how to update all the different threads with out posting a bunch of the same response's

Regardless. at this point I am still loosing coolant.

What I think Happened:
I think I had a Bad Cap that went misdiagnosed as a thermostat issue, and I then miss understood the Mechanic's instructions and installed the new thermostat upside down... which wreaked havoc on my cooling system.

That being said, when that didn't fix the issue, I replaced the cap and the issue worsened.

Now I have installed the Thermostat right side up, and there is very little heating issue. the car seems to warm up (day three) as normal, with the temp gauge only just barely rising to the top of the "N" then falling into normal range.

However, I am still loosing water. The only obvious sign of leakage is from the top of the expansion tank over-flow hose that connects to the top of the radiator (its like a 10 mm hose) one thing to mention is that their hasn't been a hose clamp there ever in the time that I've owned it, and the PO was not a Shade Tree Wrench and She had all the maintenance done at a shop)


Next Steps:
watch the oil for signs of chocolate milk
Pull the Plugs and look for a really clean one

What other things Can I do to:
1. Identify that I in fact am now suffering from a Head gasket leak.
2. Find out where my water is going and Fix this coolant issue.

Thanks all- You have been a tremendous help.
--
1979 245 DL

This is a really long shot but if you have not replaced those coolant hoses...

On my 1976 240 I had an upper hose that looked perfect. After many trials of loosing about a cup of coolant every 250 miles I removed the radiator to clean and backflush because it was an original brass radiator. I had a really hard time getting the actual hose off the neck an finally removed the clamp completely.

Right before re-installing the hose I noticed a lot of green fuzz on the part of the clamp that was on the bottom of the hose and I remembered seeing some green fuzz below the upper radiator neck when cleaning it. Rotated the hose up so I could look down it and what did I see...the neck of the radiator had cut through the inner part of the hose to the cords and the coolant was weeping out under pressure through the end of the hose at the cords.

Like I said, long shot but the hoses should be renewed anyway.

Yes, I agree. My hoses look okay- but now I am thinking that the radiator is bad as I am feeling cold spots on it after a drive, which I have been told indicates a clog.

I think my next step is to replace the Radiator and the Hoses and clamps- My only concern there is that now that I see milky oil under the Oil fill cap, that if I replace the radiator, a head gasket leak will cause it to fail.

That being said, I am barely keeping this car alive, and obviously don't have the funds to take it to a shop and have all this work done.

Do you, or anyone else out there, know a reputable Machine shop I can take my Head to in the Seattle Area?

thanks.
--
1979 245 DL

Hi,

"I am barely keeping this car alive, and obviously don't have the funds to take it to a shop and have all this work done"

Hopefully this might help. See Scotty Kilmer:
https://www.youtube.com/watch?v=YL9QjN7AcW8

Here's one way to test for combustion gas in coolant:
https://www.youtube.com/watch?v=QA7KVQq9vKA

Granted these are not done on Volvo engine but I think same principle applies here.

Amarin.

HA! THis guy is Awesome! So excited!
IF nothing else he is entertaining! ha!
--
1979 245 DL

Hi there,

I have been watching all the posts and trying to stay out of the mix because there are so many good posts being made.

I will tell you what I would do.

I have a Mity Vac vacuum pump that also will pump air to create pressure. Of course I have the coolant kit adapter that fits the necks of radiators and expansion tanks.

What I do is put the system under pressure while its cold.
About 5 to 7 PSI is plenty.

If you can apply pressure, even from a bicycle pump with a gauge and hose onto a tee placed in that little line, then, you are cooking it with gas or gases 👉 of air 👀😋.

In most cases but surely not all! I have found that a head gasket first leaks while warming up until it closes the opening.
In considering how many cycles are done daily or weekly really determines the amount of loss. Not so much the miles driven, if you ever noticed that?

As the gasket or head surface Deterioration continues, everyone knows that it can result in oil emulsion, overheating and so on!


If there is an external leak it will show up around the head gasket seam or from hoses under the hood plus around the heater valve.

If it's a heater core leaking coolant it will drain into the drain pan under it, if it has A/C and drip on top of the transmission.

You let it set with pressure long enough the level will go down.

If you see nothing then most likely it is a head gasket on the inside like Amarin says. The question is where then you do as he says look at all oils.

If it's an automatic transmission, possible damage can occur, if the trans cooler lines of the radiator give up separating the two in there.

Since oil floats on water, it takes more time for the Trans pump to stir it up than the crankshaft of an engine.
So be very watchful of your automatic fluids colors, more so than its level. Change on the intervals recommended to remove condensation.
Always check it hot! Expansion is not the only reason!

Part of the water amount can lay and spin to the outsides of a torque converter during operation and shut downs. Water is heavier or denser, so centrifugal force can hide it well in there for sometime despite any venting only from the case housing.

Then I also suggest in the mean time what do you spark plugs look like.
If you have any that stay super clean in that there are no deposit on them..? Well you found out where the coolant is going. That plug will be getting steamed cleaned by the coolant!

I hope these "anything else" ideas help.

Phil

I have also watching these posts........Good too.

I might of missed it but; exhaust into coolant?

I had this problem. Gave up and when to Volvo.

They put a chemical in the header coolant which clearly showed exhaust in the coolant

They were right!!

BrianH UK

This is super interesting.

IS that something I can get at an auto parts?

Right now I think I have a clogged Radiator and that in turn is the cause of most of my issues.

But it would be interesting to see if there were any exhaust fumes entering the cooling system, if there was an easy way to tell with out taking it to a shop.
--
1979 245 DL

Yes there is a gadget called a combustion leak detector that costs about $30-$35 at most any auto parts store.

I read someplace that there are places who rent them, which might be worth a thought for reasons below.

This kit will come with a blue fluid that has "A SHELF LIFE" so you want to see that the date is within the last year. It might last slightly longer if it's never opened!
It should be a dark blue. You gotta keep it closed up tight.

It reacts to the oxides of combustion it reacts more quickily than to normal air because air is only 20% oxygen anyway.


If the date is shorter get a discount. The stuff comes in a pint bottle for about $10 if sold separately again watch that date!

I have one that comes with a hand squeeze bulb to create a slight vacuum above the coolant to pull any combustion gases up through the blue liquid.

I have read that some model use engine vacuum to get around that but you have to run the engine for that. The combustion gases in the coolant are going rise to the top of the whole system and surface after and during an engine run. The thinner combustion Gases are lighter than even plain air.
The vacuum will entice those gases up through the test fluid.

I have a concern that care will have to be used not to get too much vacuum going and consequently pull coolant up into the testing fluid. If that happens you have to start all over and wash everything out again.
Just be prepared by squeezing the vacuum hose for control.


If it changes to yellow then you have exhaust gases.

To test the liquids sensitivity, I place the gadget into the end of a used radiator hose. I then hook it to the exhaust pipe while the engine idles. The pressure turns yellow in a blink or fast if it's good.

The liquid reacts oxygen from the air over time. Old test liquid becomes greenish yellow, so you know it gotten old.

A radiator is suppose be cooler in the bottom third as the coolant is supposed to be cooled by then.
I agree if you had cooler spots along that area that would raises suspicion of the possibillity that there is a lack of flow.

Like I said though you will only see it drop about 30 degrees.

That's only a rule, of my big thumb!

Phil

Hi,

"However, I am still loosing water. The only obvious sign of leakage is from the top of the expansion tank over-flow hose that connects to the top of the radiator (its like a 10 mm hose) one thing to mention is that their hasn't been a hose clamp there ever in the time that I've owned it"

Put hose clamps over those two ends. The 200 series uses coolant "expansion" tank system which is part of the main coolant pressure. This is to make sure there's no way for steam or coolant to escape.

If coolant still becomes low after you have eliminated its escape then the last possible place is the head gasket. Also eliminate loss of coolant into radiator transmission cooling hose by checking the transmission fluid not becoming milky (if yours is auto).

Amarin.

Amarin

Thank you for the reply.

I must say that my only concern is that by using a hose clamp there, that I might blow a Hose due to pressure. to that end, in the last 10 years i've owned the car it has never needed a hose clamp...

My understanding of how the Cap works is limited, but on my old ford, the cap would let out any excess pressure (the ford would over heat due to a timing issue way back)

Regardless, could I expect the same functionality from the cap on the expansion tank? It is recently new, as my last one allowed for boil over, so i replaced it.
--
1979 245 DL

So, you have a new cap? Pressure is holding? No leaks. Glycol mix coolant no longer being lost?
--
Art Benstein near Baltimore

Do not argue with an idiot. He will drag you down to his level and beat you with experience.

Art,

With the expansion tank overflow/return hose clamped I still every now and again hear a Whistle so some coolant is still leaking from there under pressure.

Cap is maintaining.

that being said, I recently have discovered milkyness under the oil fill cap telling me that the Head Gasket has blown...

TO that end, it was suggested to me to feel the radiator after a drive for cold spots indicating a blockage, which in fact there are cold spots on the lower 2/3's of the radiator...

At this point, I feel like the radiator needs to be replaced, and a new head gasket installed.

I am hoping not to have to have a shop square up my head and that it did not suffer any real damage.

What is the best way to self diagnose a head with limited tools?

thanks
--
1979 245 DL

OK, so no progress then. I was going to let you know there are some aftermarket caps with a reputation less than stellar. You should take your original black cap, wash it, and compare. Also, the advice to clamp your hoses, where there were no clamps originally, supposes you are not replacing your hoses. That they need clamps now, where none were before, is a result of the hose losing* its elasticity.

"I recently have discovered milkyness under the oil fill cap telling me that the Head Gasket has blown..."

This is a bit of a leap. Of course you are there and I am not. Please start a thread with this as the subject before acting upon this assertion.

*lose rhymes with booze and loose rhymes with goose
--
Art Benstein near Baltimore

Why do banks leave vault doors open and then chain the pens to the counters.

I'm not saying that this is your problem, but keep in mind that if you have a head gasket leak between the combustion chamber and a coolant passage, the gases, as bubbles, can travel through the cooling system to the overflow tank -- as they rise, it can look like boiling when, in fact, it's just the release of the gases.

Repair shops should have a "sniffer" that shows whether the fumes in the overflow tank contain combustion gases.

Good luck.

Ken-

that is super interesting. Thank you. After I chase all the easy stuff I'll look at that.

actually, i'm begining to think that replacing the head gasket wouldn't be that troublesome - I just dont have the tools easily accessible...
--
1979 245 DL

General rule IME, If the temp is related to speed - more speed = higher temp - it's a clogged radiator. I've had several of these. So you could do a radiator flush - the mild kind - and see what you get out of it.

My driver has had a bad cap (no pressure) for a few years. I've never seen a bad cap (no pressure) cause overheating in a 240. I'm not saying it can't happen. Just IME.

I had some old equipment (tractor, military truck) have the impeller loosen and spin free in the cavity. Usually a bad water pump leaks and is noisy.

If you're adding water to yours, perhaps you have a leak. Check compression for a failed head gasket.

The aluminum heads in these cars won't take much overheating.
--
240 drivers / parts cars - JH, Ohio

John,

Hey- I have noticed a bit of speed related heating, but only acceleration, at constant speeds it cools well- it is really interesting, which is why i am now suspecting the Fan Clutch.

I did a flush, and i saw virtually no gross debris or anything come out. Just dingy coolant.
However their was a coating of some kind in the reservoir / expansion tank that had some bits of slimy stuff come out when I back flushed and wiped it out. same color as the dingy coolant - but that was it.

Even looking inside the radiator, it looked clean inside, and their is no reason for me to suspect it is new or a replacement.

That being Said, Any idea's on how to test a fan clutch?
--
1979 245 DL

I'd suspect the reservoir cap. It is supposed to maintain a certain pressure above atmospheric to prevent the water from boiling.

If it is defective it may be allowing the water to boil thus lowering the efficiency of the system.

While the engine is running and warm, unscrew the cap. If water pours out then it is working. If it doesn't then it is likely not maintaining pressure.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

I just tried the Mobil version of the site... Looks like it didn't quite work

So, I replaced the cap and it appears to have stopped the boil out.

I replaced the thermostat and the temp is riding high on the "N" pretty consistently. So far though it hasn't had a major temp spike since the new cap...

Although, I think I have the wrong thermostat. The Volvo guy I bought my cap from said I needed a thermostat that ran cooler, like 83* Celsius. The one I pulled from the car was 87*C and the one I installed is rated at 90*c or 195 F.

I was wondering what the "correct" temp rating for my 79 should be. The parts house says they can get me an 82* or 88* thermostat.

Thanks.

"The one I pulled from the car was 87*C and the one I installed is rated at 90*c or 195 F."

Hotter thermostats are preferred because they improve combustion and mileage. If your 240 maintains its cool in hot weather, stick with the 90*C thermostat.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

How do you tell the temp of a thermostat. I am looking at the one I just removed and it doesn't have a marking that I can distinguish as its temp value.

IT susually stamped somewhere on the thermostat itself. Mine have all been stamped on the bottom near the Spring
--
1979 245 DL

Are you using coolant or just water? Try cleaning the radiator fins with a hose as they could be clogged up with bugs leaves debris, etc. Could be the radiator is clogged internally. Are the cooling fins intact on the radiator? Does turning the heat on bring down the temp guage?

JoeKidd-

thanks for your response. I had just added water. The fins are in good shape and there are little to no debris in the radiator itself.

Good Question about the Heat- I have not noticed a difference if I turn the heat on.
--
1979 245 DL

""" The fins are in good shape and there are little to no debris in the radiator itself. """

have you looked Inside the radiator? it could be clogged.

Drain off enough coolant so you can remove the top radiator hose and look inside.
Are the channels on the top stuffed up with a whitish gunk?

If it is the original Metal Radiator, you may be able to find a Radiator shop that can test the Flow...and Hot Flush this gunk out.

Metal Radiators can also be taken apart... the top and bottom Brass sections unsoldered and the core reamed out. Known as Rodding.

However, since most Radiators are now Plastic/Aluminum...no many shops can do this.


As for the Fan Clutch...read the FAQ. Cold engine: no resistance Fan spins freely. Operating Temp and Hotter: the clutch offers resistance so that the Fan Spins at higher RPMs matching the speed of the water pump pully. Has a "spring like" mechanism that expands as it gets hot. The idea of the Clutch was to allow quicker warm ups.
In the WayBack the 60s, fans did not have a clutch and just spun at a constant speed.

A failed clutch will not get the fan to run faster as the engine gets hot.


I

CB-

I've searched the FAQ and could only find ifo on the thermostatic fluid type fan Clutches- and it didn't offer any ways to test it.

Do you or anyone have a link to the FAQ section on testing the fan clutch?

Thank you!
--
1979 245 DL

CB-

thanks for the response. Some how I missed it until now.

I haven't looked inside the radiator. It looks nearly brand new- and it is metal. It is in great shape.

I dont really have the means to drain any fluid out- I was just thinking to call around and see what it might cost me to have one of the cheap lube places do a hot Flush. Any idea what that might cost?

Also, Im not sure you had seen my other response but, i replaced the thermostat with a new one and it still Spikes Hot and then Rides the top of the "N" while driving. The one I had got was a 195 *F thermostat (90*C) and the one I pulled out was an 188.6 *F (87*C) one. the Volvo mechanic I spoke to gave me another temp to look for- which I cant remember...

IPD lists a 191*F (88*C) but that one doesn't seem like the one the Volvo Mechanic was talking about either...

Do you or anyone else have the Spec on what temp thermostat my 1979 245 should have in it? I'd like to rule out the thermostat as I go through the process! ha! (especially since it is so easy to swap out!)

Thanks!
Gaz.
--
1979 245 DL

If the radiator looks new then it ain't the original.

If you have removed the Thermostat then you've drained enough coolant off to empty the top hose. Easy look inside the rad with a lite and a mirror(if necessary).

The difference between the Degrees on the thermostat makes little difference to the operation of the B21 engine that you have. The only differece is that in the winter you will get heat sooner inside the car, as the thermostat opens a tad later.

No "cheap lube" place will even know what a Hot Flush is. (Never ever let a "cheap lube" place touch your Volvo, even to change the oil)

Having the Temp run on top of the N may have nothing to do with the functioning of the cooling system.

Do you really think that a 1979 guage is perfectly accurate?

If you are still having "near the Red Zone" readings and you are sure you have a newer Unclogged Radiator, then you need to get an accurate Temp reading on the system.

Once you establish this...post your findings.

CB-

It's been awhile since I've attempted to tackle this problem

I've been nursing along adding water as I go, and as it goes off.

Recently (a month ago) I replaced the Cap, which seemed to help a little. It would rise up to HOT, and fall to normal pretty consistent, then I'd need to add water.

I drained it, looked inside the Radiator and found it to look in really nice shape inside. Do deposits or any gunk inside.

In the reservoir (over flow) there was a coating of some stuff that I was able to get most of it out.

Just over Christmas I replaced the water pump. Previous to that I had seen a little coolant on the pump and couldn't tell where it was coming from, so I just replaced it.

I flushed the system twice with water from the hose, and it looked clean.

Since then, the next day, it was great. the Temp gauge only rose to the top of the N before it fell back into normal range and it seemed wonderful.

I then drove the car for about an hour and a half. When I checked the water level the next day, it had lost all the water in the reservoir. It took 1/2 a jug of water to bring it back to level.

The water is going somewhere- and I cannot find a leak.

Just yesterday I did hear the Cap whispering the faint sounds of what I thought was venting of some kind.

I have a virtually clean system.
New Pump
New Thermostat
no leaks accept for old boil-over's and what might appear to be the beginnings of boiling over again.

What could be the issue?

Thanks-
--
1979 245 DL

Hi,

"When I checked the water level the next day, it had lost all the water in the reservoir. It took 1/2 a jug of water to bring it back to level."

When you changed the water pump, almost all water is drained from the upper cylinder head. On the first refilling expect the level to go down again after the water had filled back those spaces. I usually fill my reservoir more than the "max" level during that first refilling (after water pump or thermostat change). It would go back to between "max" and "low" after one or two driving cycle.

Always use coolant/antifreeze mixture. Antifreeze contains surfactant to make the water more adherent to the inside surfaces (thus it absorb and transfer heat better).

Now if you need to fill back the reservoir after the coolant level had stabilised or the coolant level never stabilises, that means there's a leak somewhere. This is when the engine had cooled down.

A thing I observed when my head gasket leaked a little (had to top up coolant frequently) last time was the coolant level in the expansion tank would rise up past the "max" level till the mouth of the tank (the cap was still there screwed tight). And sometime coolant would rise till it overflows thru the cap to outside. This when the engine was running.

Amarin.

How did you come to find out that the HEad gasket was leaking?

I have no water in my oil, and no steam in my exhaust - which tells me that my head gasket is fine.

Should I be looking for other signs that would tell me that it's blown?
--
1979 245 DL

It may well be a head gasket. I see this thread has been going since last May with no resolution.

I had overheating problems with my '85 Camaro for years. First it was just while waiting in the staging lanes at the drags, lapping on a road course, then in heavy stop-and-go traffic in the summer. I tried many solutions, new rad, dual electric fans, new water pump, but it just got worse over the years. A year ago it was so bad I couldn't even drive it without boiling out of the overflow tank. That's when I concluded it was a head gasket and changed them.
--
1992 745, >500k km

In my case the water pump belt had broken while I was highway driving. Power steering had lost its assistance but only able to stop after finding an exit. Didn't dare to stop by roadside after seeing many youtube videos about cars being hit by roadside.

The temp had already risen to red. Installed a spare belt but then didn't wait long enough for engine to cool (about 1/2 hour). Poured in water and it was still steamy inside. So I thought there goes my head gasket!

But the car can still be driven home afterwards plus daily driving. Realised had to top up coolant 2-3x per week compared to before once/twice per year. Replaced the gasket 3 months later with a used cylinder head.

Amarin.

Get the engine to running temperature, the cooling system will be pressurized. Then look carefully everywhere you might suspect a water leak to be coming from, including the heater hoses behind the head.

Dan

Pageda-

I've done this a few times, and the only thing I see is, well, nothing. However I do hear escaping air at the expansion tank cap.

I am wondering if maybe the expansion tank is warped at the the threads? I replaced the Cap a few weeks ago with little change as it continues to have boil over issues.

also, I am now considering that my Fan clutch may have gone bad (original since 79) IF that was the case that might make sense as to why it heats to normal in my driveway, but while driving it rises and falls, rises and falls, rises and falls and eventually has some boil over...

Any thoughts on how to test a fan clutch?
--
1979 245 DL

"However I do hear escaping air at the expansion tank cap."
Then your system isn't pressurizing and water is boiling off. Don't worry about a head gasket or fan clutch until you get the system sealed. The system needs to be pressurized for effective cooling. And use antifreeze with distilled water or buy premixed.

Fill the reservoir to the level indicated then use Saran wrap under the cap to seal it. There will be a bit of expansion but it will be taken up by the air space in the reservoir. If you have a head gasket leak into the cooling system, then there may be boil over.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

Trev29-

I tried what you suggested.

First thing this AM, 0830, I went out to the car, checked the fluid level, it was between Min and Max on the Expansion tank. I used Saran Wrap under the lid, and Drove the Car.

10 min in, the Temp gauge rose up to normal, then peaked up under the "red Zone" just under while still in the green. it never touched red.

Then the temp gauge stabilized in "Normal" range.

I went on the Highway, and drove aggressively up to 70 MPH just briefly. The temp gauge stayed in "Normal range"

I exited the Hwy to an off ramp where then the Car Squealed at me quiet loudly.

Temp gauge still in Normal range.

0900, Parked the Car, opened the hood and noticed a leak from the Top hose on the Radiator to the Expansion tank (the small 8mm hose that leads back to the expansion tank)

Looks as thought the squel I heard was coolant escaping from the Hose.
that

1200: went out to Check fluid level. Opened the expansion tank cap and it hissed as per usual when Hot (thought it would be cool by now).

Removed Saran wrap and looked at fluid level.

Fluid in the expansion tank is below the "min" and there is just barely any in the tank.

I put the cap back on with saran wrap again.

What next? what does that tell us?

Thanks!


--
1979 245 DL

"What next? what does that tell us?"

The Saran wrap was to seal the system if it was leaking at the cap and prevent the cap from venting if it was defective. And the air space in the reservoir was to provide expansion room for normal pressures.

But since the small hose leaked it indicates that fluid had filled up the tank (taken up the available air space) and forced itself out.

Seems to be pointing to a small head gasket leak that's providing additional pressure-volume.

However, if you're still using only water then higher pressures-volumes may be reached under normal operating temperatures.

"Fluid in the expansion tank is below the "min" and there is just barely any in the tank.

So since there's still a bit of water in the reservoir, don't add any more and run the car, but keep a full bottle with you and your eye on the temp gauge. If the car runs fine and no more water is lost, assume that an almost empty reservoir is normal for only water.






--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

Seems to be pointing to a small head gasket leak that's providing additional pressure-volume.

Long time ago when the yards still had turbo 240s in them I decorated my 300K beater daily driver non-turbo 84 240's dash with a gauge pod. Having previously put the boost gauge to work as an "eco" meter and being bored with its expected feedback, I plumbed it into the cooling system to see what I could see.



Having enough theory background to know cooling systems are operated at pressure to raise the boiling point and make the engine more efficient, I wanted to see how it played out in practice.



Now Trev29, I'm not suggesting the OP do this, really, as the 79's gorgeous interior appointments are not easily amenable to the 81+ gauge options. But maybe as a diagnostic...



The idea of combustion gas raising the pressure is a strong clue. This would, in my experience, occur before the coolant temperature has reached its peak, although I can envision gasket faults where the timing is indistinguishable.



A pressure gauge on a radiator tester can be used by connecting in the same way. This will reveal the cap's release point, and with the pump feature, any leaks that would keep the system from becoming pressurized.



Without the purpose-made tool, you can get in dutch with your wife as I have, appropriating her garden sprayer, modified with a tire gauge. This uses a modified cap, but yours could tee into the reservoir hose.



--
Art Benstein near Baltimore

"Everybody's got to believe in something. I believe I'll have another beer." (W. C. Fields)

"The idea of combustion gas raising the pressure is a strong clue. This would, in my experience, occur before the coolant temperature has reached its peak, although I can envision gasket faults where the timing is indistinguishable."

Yes, it is likely combustion gas EXCEPT that J-Gaz is using plain water.

So assuming it is not a head gasket leak, could plain water be boiling and increasing system pressures beyond the cap's release point (assuming the cap is not defective or loose)? I don't know. That is why I suggested keeping things the same and doing another run. If the water level remains the same then the system may have equalized around plain water as the coolant. If the level drops further, then there's a leak.

Head gaskets aren't that easy to change so it's best to be sure. Me, I use antifreeze.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

There are test kits which can tell you if combustion gases are getting into the coolant. That would be a useful test.

https://www.youtube.com/watch?v=a3J00_e7fyo and lots more.

Uncle J-Gaz.,

No one mentions using distilled, demineralized, or distilled water. Or using premix coolant to top up a low engine coolant level.

NEVER use tap water as engine coolant!

Do you have any anti-freeze as coolant mix in your 240 engine at all?

Also, have we considered a faulty temp sensor or faulty temp faker board.

Yes, a compression leak from one or more cylinders through a failed cylinder head gasket seal, or, with all the incidence of low coolant levels, you may have run your 240 with little or no coolant in the cylinder head, so cracks can form in the thinner sections of the light aluminum alloy material from when the cylinder head is cast.

With the engine off, yet still hot, coolant can flow through the cylinder head leak and into the combustion cylinder. If barely a drip.

As cold as it is now in North America, it may be hard to discern excess steam in the exhaust. Can you smell the anti-freeze smell if you have the usual 50/50 mix or so in the cold exhaust. Even 30% antifreeze coolant mixture can reveal the antifreeze smell in the exhaust.

The pressure driving from a combustion chamber into the coolant jacket causes voids (bubbles) in the coolant, reducing coolant effectiveness.

My guess is you'll find a cylinder head leak. During your removal of the cylinder head, fully inspect the engine coolant system. Things like aforementioned clogged radiators, faulty coolant thermostat in the thermostat housing, faulty (fuel injection & engine coolant temp gauge temp sensors).

If you've been running your Volvo using water only, at the current North American ambient Winter temps, the coolant can freeze. If your lucky, a freeze plug or more pop out, or worse.

Hope that helps.

Questions?

cheers,

Crappy Old and New Year.
--
The mightiest Volvo ever: The Mighty Volvo 164

kittysgreyvolvo-

Hey, thank you for the response.

I flushed the engine with well water. I don't have hard water (no mineral deposits- therefore no need for distilled water)

I am running Coolant in it. For/ during the Flush I used water so that I could see any debris in the water as I was flushing the system.

There is no Antifreeze smell in the exhaust, nor any water in the oil.

I do not suspect the gauge is bad because if it were it would erratically also dip below normal range rather than rising as per usual and only going to hot, then falling within normal range. if the gauge or the Board were bad, wouldn't we see the gauge also drop at dramatic intervals erratically?

as of now. the only place I hear a potential Leak is back at the Expantion tank Lid (3 weeks new).

Therefore, my new suspisions are:
1. The Expansion tank itself (original and difficult to put the cap on) {threads warped?}
2. the Fan Clutch (Original to the Car- sitll the aluminum fan blades and OE fan clutch- may finally given up)

That being said- How would I Test the Fan Clutch? the fan spins with the engine, and spins freely with the car off?

Thanks-
--
1979 245 DL

"When I checked the water level the next day, it had lost all the water in the reservoir. It took 1/2 a jug of water to bring it back to level."

If you are living in an area that sees below 32F, you should be using radiator antifreeze to avoid ice forming in the cooling system and possibly destroying it.

Rad antifreeze also raises the boiling point of water lowering boil-off and improving its heat transfer efficiency.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

take a nice drive where the car has been warn for a while. Pull over and pull all 4 plugs. I would bet that one is very, very clean. if so, you have a very small head gasket leak.

The obvious question is everytime it was low, did you just add water or a mix of water and coolant?
--
Post Back. That's whats makes this forum work.

Aleekat- that's a good question. the Short answer is Tap water. I live in and area where the water is very soft, so I don't need to think about calcification or deposits blocking up the flow- or that is what I tell myself.

Basically, this is the first instance I have ever needed to add coolant - I have been adding water of the last 3 weeks.

I've never flushed the Radiator. the water pump was newer when I Bought the car. Ive had the Car from some time but just recently (last 3 months) it has become my daily driver.

That being said- I have read a little about the fan clutch and haven't come across anything that really tells me how to test it.

It feels good when not running and rotates freely - no real drag or anything, and when running it looks like its moving air. No binding or noises.

Doesn't mean its not the cooling fan clutch-
--
1979 245 DL

The fan may be turning, but not really pulling air if the temperature sensitive clutch is worn out.

Try a FAC search on fan clutch (top right corner) for ways to test it.


--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

On my B20F engine I was under the impression that the fan clutch is designed to match the engine rpm until is starts to release at about 4000 RPM. If that is the case, one shouldn't be able to spin the fan freely when the engine is static. Is this true?

I loosen the alternator belts, and warm the fan clutch up with a heat gun and, and I can feel the difference in the fan spin between hot and cold.
In regards to the overheating problem what, do you think about this

https://www.brickboard.com/RWD/volvo/727750/220/240/260/280/way_thermostat.html

deals with thermostat orientation re the inlet housing.

I just got dragged through colicky Toyota hell, i replaced a radiator, water pump and timing belt on a Camry . It took me three days to finally get all of the air out of the cooling system, with symptoms very like what have been described here.
Just a thought

Bones and Feathers-

You bring up very interesting Points.

First, Yes - I swear that the Volvo Guy I asked said the orientation of the thermostat be in the 6 O'Clock Position- Where as the one I pulled was Most definitely in the 12 O'clock position.

I will rotate that immediately.

Was that part of the issue with your Yota?


In regard to Air Bubbles in the system:

My Heat used to be Bake a Pizza HOT. But since this issue, and since I replaced the Thermostat, The Heat, Blows Cold. Whats more unusual, is that when the it blows cold, the Temp Gauge in the Dash is showing a rise in Temp.

Lastly, I did as Trev29 suggested, and used some saran wrap to help seal the Expansion Tank Cap- which seemed to Help... until, now I have a very noticeable leak from the Upper most hose on the expansion tank as their are no Hose Clamps Holding that hose on.


It should be known (synopses) that My initial issues were the Rise and fall of the Temp Gauge and Boil over in the Cap.

Replaced the Thermostat (probably didn't need to), then had the Cap Tested after symptoms worsened, and replaced the Cap.

After the continual worsening of symptoms, I Flushed the system with Water until it was Clean (2 flushes), Replaced the water pump and filled with coolant mix.

Now I add about 1/2 gallon of water every day, as it just spits it out through the small expansion tank hose where it connects to the radiator. Furthermore, the system maintains Pressure after Cooling over night, meaning that in the morning after over 10 hours of the car being parked, I can loosen the Cap and it will release some air pressure from the cooling system.
--
1979 245 DL

"the system maintains Pressure after Cooling over night, meaning that in the morning after over 10 hours of the car being parked, I can loosen the Cap and it will release some air pressure from the cooling system."

So where could that excess pressure be coming from? The cooling system is basically sealed, so expansion from heat will be negated by cooling overnight.

But since there is enough pressure to force out coolant from the small hose and there is still residual pressure after cooling, then something is adding pressure to the system. Looks like a one-way head gasket leak?
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

If your cap is good the pressure above the coolant in the expansion tank will rise. This increase in pressure raises the boiling point of the coolant. If you then take the cap off The coolant will then boil over due to it no longer being under pressure. Very dangerous thing to do! If you've taken the cap off when the coolant is warm and has only expanded bit, and you take it off again when the coolant is cold the small woosh you hear will be air going in to replace the vacuum, not pressurised air coming out. Get some clamps on the pipes where they are missing. If you are getting fluid leakage you also won't be building up any pressure to increase the boiling point. New cap but make sure the top flange of the tank is smooth. Screw down tight. I've made this comment elsewhere but soon after I got my '92 wagon it started to show much higher temps than it should and also started to run very rough. A quick visual check of the tank showed the level to be OK. However, this was a false reading as the inside of the tank had a brown scummy coating that made it look like it had coolant in. In reality it was empty and as the hose to the rad joins the side tank half way down, meant that the system was only half full! I did fit a new thermostat as well as renewing my antifreeze, and the car hasn't missed a beat since.
Re the heater, I'm sure it's already been mentioned, check the valve for leaks and that it actually has the wire connected to it. Once you have the system pressurising properly it will of course make any leaks here more obvious.

My Heat used to be Bake a Pizza HOT. But since this issue, and since I replaced the Thermostat, The Heat, Blows Cold. Whats more unusual, is that when the it blows cold, the Temp Gauge in the Dash is showing a rise in Temp.

Hot engine and no heat in cabin says there is not enough water circulating through the heater core, for one reason or another. Looking at the thermostat would have been my first thought also.
Fortunately in a normally aspirated 240 there only so many places for water/coolant to go, and only a few to regulate it.
When you take off the radiator cap there should be no pressure release, unless it's hot. Iffen its cold it should just sit there, when you open it. My Yota has a more nearly sealed system and water wont go into the radiator from the expansion tank unless it's drawn in (so my son says, but it appears to be so). In a 240 you pour water into the tank and it goes into the radiator,as long as there is room for it.
So, either the water isn't moving, or there is an obstruction somewhere, preventing the fluid from getting where it's supposed to go,
I have never had a problem with air in the coolant , till the Yota, and apparently it's common,in the breed (porsche has a bleed valve for this purpose, or you leave it sit for week and the gas bubbles to the top)

So our players are

Radiator

water pump, belts, pulleys, seals,hoses(pump to radiator, engine to radiator) out put pipe to input hose to heater core), fan, fan shroud, fan clutch

engine block,( block to heater core hose)head gasket,thermostat, thermostat housing gasket

heater core, heater control valve

Check all the easy stuff first, and don't overlook the obvious (my personal favorite).
I need a little more time to think this through as i generally think with my hands and eyes, and i'm not a great mechanic, i'm just generally too broke to pay anyone else to fix my cars. I make a list, of symptoms, and suspects and beat on it till it runs.
I'll see what else come to mind, i gotta get ready for work.