so I replaced my son's breather box when the aftermarket breather box it had in it broke in two and slathered oil all over everything.

I noted at the time that his oil pressure was seemingly (to me) very high at almost the top of the 5 bar gauge. I wondered if the high oil pressure blew up the breather box until others here told me that aftermarket boxes are not always that good and have broken before.

Needless to say I cleaned and buttoned it all back up and the pressure was still pretty high around 4.5 bar and 3.5 bar at idle after long warmup.

my son drove it for 2.5 months or so then it started to stall when it was wet out... once stalling when dry. I switched my S70 to him and took his 240 and noticed it was running kind of rough and saw the oil pressure gauge was hovering just above 1 bar!

so now I'm wondering if the oil pump seal/o-ring wore out suddenly or if the valves wore out that fast...

I'm afraid I'm pretty much a novice about anything from the valve cover to the oil pan.
--
2 1990 Volvo 240s - 1 is my son's sedan the other my 245 in restoration, 1 1999 S70 is my current daily driver until I can get back into the 245!

Thanks to all who saved me the trouble of taking off my oil pan.

After my replacement of the oil pressure gauge the reading has been consistent and normal. Although I'm having trouble with poor idle and stalling when it randomly does run and drive it shows high pressure (4.5 bar) at first start and heavy throttle and then lower pressure (2.5 bar) after running for awhile and at idle (when I can keep it from stalling!).

Once again the brickboard has helped me solve a challenge - thanks for the solution!

Do I need to flag this issue as resolved somehow?
--
Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

New update on current situation with rough running and random stalling

(Fwiw my friend is bringing a mechanical oil pressure gauge so we can check actual pressure against gauge.)

While driving a few days ago the car stalled and I was able to restart it then a later time it stalled at a stop sign and wouldn't restart. I unplugged AMM after several failed starting attempts and the car started and limped home 2.5 miles.

When I had time to troubleshoot I noticed the AMM contacts had some white corrosion and were a bit tarnished so I cleaned them up and the car started running pretty good.

Then the next day I took it for a test run to see if problem was fixed and it seemed to run a bit rougher again and after a half mile it stalled and wouldn't restart again. This time I unplugged the AMM and it didn't start. Left it sit for two hours and brought all my no start tools to it and it started up (still in limp home mode) so I drove it home the half mile and plugged in the AMM and it started but is currently running rough.

So I haven't yet repaired the EGR connection leak (my friend and I will do that in the next day or two) but I'm thinking a vacuum leak wouldn't cause it to crank but not start (my assumption is that it would start back up and run rough).

The random nature of the fault and the escalation to not starting after stall seems to make me think it's fuel related but I will see what happens after the EGR connection repair.
--
Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

New update on current situation with rough running and random stalling

(Fwiw my friend is bringing a mechanical oil pressure gauge so we can check actual pressure against gauge.)

While driving a few days ago the car stalled and I was able to restart it then a later time it stalled at a stop sign and wouldn't restart. I unplugged AMM after several failed starting attempts and the car started and limped home 2.5 miles.

When I had time to troubleshoot I noticed the AMM contacts had some white corrosion and were a bit tarnished so I cleaned them up and the car started running pretty good.

Then the next day I took it for a test run to see if problem was fixed and it seemed to run a bit rougher again and after a half mile it stalled and wouldn't restart again. This time I unplugged the AMM and it didn't start. Left it sit for two hours and brought all my no start tools to it and it started up (still in limp home mode) so I drove it home the half mile and plugged in the AMM and it started but is currently running rough.

So I haven't yet repaired the EGR connection leak (my friend and I will do that in the next day or two) but I'm thinking a vacuum leak wouldn't cause it to crank but not start (my assumption is that it would start back up and run rough).

The random nature of the fault and the escalation to not starting after stall seems to make me think it's fuel related but I will see what happens after the EGR connection repair.
--
Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

Ok we found a vacuum leak - EGR connection to intake manifold, had a broken bolt on one side of that connection (not repaired by lazy mechanic - yours truly) since the other bolt seemed to be adequate at holding the connection tight.

Now it seems the one good bolt's threads are stripped so it won't tighten and that leaves the connection loose enough to let air in post AMM.

Looks like it's finally time to fix it right!

As for oil pressure change I'm gonna try to get under it and twist off the oil pan to see if I can look at the o-ring to see if it has failed as you guys have suggested.

Now to find an ez out, some thread cutter tool, a couple of new bolts the size of the EGR connection bolts and some motivation (last is harder to find as laziness seems to accompany old age!)

I'll keep you updated as to oil pressure troubleshooting.

Thanks for the confirmation that the dreaded two simultaneous unrelated problems has struck me again!
--
Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

The sudden reduction of oil pressure could be explained by a common o-ring displacement at the end of the oil delivery tube output from the oil pump. I can't envision a connection between oil pressure and crankcase ventilation pressure which you'd see as an oil leak around seals, oil dipstick, cam cover, and of course, that aftermarket oil separator.

Rough running is often a vacuum leak. Stalling when wet has so often been a distributor cap in my experience, followed closely by a worn old set of ignition wires.



A '90 240 doesn't come with an oil pressure gauge, and its stock warning switch is set at 0.5 bar (7 psig) so your added gauge sender is always a suspect tracking over long term, especially as to the 4.5 bar history.

What is the oil maintenance history? Filter change affect the trouble?


--
Art Benstein near Baltimore

Nobody sees a flower - really - it is so small it takes time - we haven't time - and to see takes time, like to have a friend takes time. - Georgia O'Keeffe

Sorry you all have given great ideas and I have been almost completely buried with other challenges in my life to respond.

I'm pretty sure engine tune is good but I can check cap and wires (maybe run them thru my dishwasher at night when the wife is not looking!).

Oil and filter was changed recently when I replaced the aftermarket breather box that you all helped me with about 8 months ago but I have a lot of filters so I could change it to see.

"A '90 240 doesn't come with an oil pressure gauge, and its stock warning switch is set at 0.5 bar (7 psig) so your added gauge sender is always a suspect tracking over long term, especially as to the 4.5 bar history"

Art - do you mean I should suspect the sender just wearing out? Would you recommend swapping in another sender to confirm original sender is good?

I will get back to this next week when I have some more time but thank you Art and everyone for your helpful input!
--
Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

Sorry you all have given great ideas and I have been almost completely buried with other challenges in my life to respond.

I'm pretty sure engine tune is good but I can check cap and wires (maybe run them thru my dishwasher at night when the wife is not looking!).

Oil and filter was changed recently when I replaced the aftermarket breather box that you all helped me with about 8 months ago but I have a lot of filters so I could change it to see.

"A '90 240 doesn't come with an oil pressure gauge, and its stock warning switch is set at 0.5 bar (7 psig) so your added gauge sender is always a suspect tracking over long term, especially as to the 4.5 bar history"

Art - do you mean I should suspect the sender just wearing out? Would you recommend swapping in another sender to confirm original sender is good?

I will get back to this next week when I have some more time but thank you Art and everyone for your helpful input!
--
Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

"A '90 240 doesn't come with an oil pressure gauge, and its stock warning switch is set at 0.5 bar (7 psig) so your added gauge sender is always a suspect tracking over long term, especially as to the 4.5 bar history"

In other words, check against a known good mechanical pressure gauge before jumping into the work needed to pull the oil pan. Gauge sender and gauge, whether you got it new or used may have had a fault.

--
Art Benstein near Baltimore

A woman marries a man expecting he will change, but he doesn't. A man marries a woman expecting that she won't change, and she does.

Ok Art (and anyone else still looking at this thread)

I am fairly certain the oil pressure gauge is the problem. While doing some troubleshooting on my son's hazard warning flashers I thought I'd switch in my other oil pressure gauge (I still haven't had the time to wait for the engine to cool long enough to apply the mechanical gauge)

For the last 3 trips the gauge seems to be acting normally (4 bar at startup and full load then down to 2.5 bar after running for awhile and at idle)

I'm going to start a separate post about my rough running since I finally got a CEL and socket 6 produced a 144 code

I will update again after mechanical gauge has been applied for further confirmation and gratitude for saving me from removing the oil pan!
--
Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

Hope you're right. I'll check your ignition thread now.
--
Art Benstein near Baltimore

"He drank like a man who wanted to get this life over with." -Mitch Albom

Ok I'll get a friend's mechanical gauges and check it... easier than pulling pan (I get it) I may also pull sender and gauge from known working car and see what it says.

Thanks Art
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Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

One of the worst things that can happen during troubleshooting is to have a second problem develop during the process.

(I spent 3 years in the Army doing electrical troubleshooting)

The rough running may be related to the oil explosion getting oil in the wrong places.

Even an invisible coating of oil in conjunction with moisture may be causing the rough running.

At night, run the engine for several minutes to warm it up then spray a fine mist over the engine while it is running in the dark,

You may then see some sparks that are getting away.

You could wash the ignition wires, including the distributor cap and coil wire, clean the coil, especially the top.

(One of the Brickyard members puts his in the dishwasher!)

Then check to see if all the looms and parts that hold the spark plug wires apart and away from metal are present and in use - Most 740s that I bought used were missing nylon wiring clips and plastic wire separators.

As for oil pressure, I have even seen advice that if the oil pressure light is flickering, turn the idle up a bit.

Check for proper idle speed with a good tachometer - things like a dirty air filter, or wear and tear can reduce idle speed.

How old is the engine's general state of tune? Volvo computers can adjust for small problems until they get pretty bad and cause problems. If you do change some items, run the car for several days until the computer can adjust to the new items.

Oil pressure as low as that is certainly a cause for concern.
Some possibilities:

1. Faulty gauge?
2. Run a crankshaft bearing - does the engine knock?
3. Failing oil pump.

Others may have some more specific advice relating to 240s.

I would advise to stop driving it until you get it resolved.

Ian F

Engine isn't knocking but is running rough and stalling Intermittently when wet, maybe there is an electric problem as well. Since it's running rough and it was running fine when I handed the car over I'm thinking gauge is fine and maybe sender too.

I have another sender I can swap in

Oil level and oil is clean and good

I may check the wires and cap just to rule that out

Another question would be - with low oil pressure would the car run rough?
--
Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

Very unlikely that oil pressure is causing rough running. The fact that wet weather correlated with rough running suggests electrical problems - as Art points out.

Yes, check oil pressure with a mechanical gauge. I got one from Harbor Freight for about $30 and it's a decent rig, plenty of adapters to fit nearly anything. Definitely proves low pressure - or not. Here you go:

https://www.harborfreight.com/engine-oil-pressure-test-kit-62621.html

In my experience- no, low oil pressure would not make the engine run rough, although they may be linked in some way.
If a failed bearing is causing excessive friction for example, but I would expect that to be very noisy.

Oil pressure of 15 psi would be enough to keep the bearings lubricated, the key thing is the sudden drop in pressure which I would associate with increased clearances somewhere in the lubrication system. Often is excessively worn bearing or oil pump.

It's not the oil pressure which prevents metal to metal contact, that's done by the oil film which 15psi should be capable of supplying.

Just my opinions of course,

Ian F

Thank you Owen!

I'm gonna try to look for the oil pump seal problem that Art has mentioned.

--
Bad Blue - '86 245 with 303,000 mi. (now for parts), Good Green 1990 245 with 178,000 mi., Blacky - '91 740 wagon with 180,000 mi., Mean Green - '94 850 with 222,000

Check oil pressure with a mechanical gauge. Poss faulty gauge but more likely the sender. Swap in another oil filter, especially if it isn't a Volvo one.