Hi all:

I noticed that the level of the coolant in the expansion tank keeps dropping after each day of driving. I tried looking everywhere to find the leak but nothing. Not even a smell.

Internal leak a possibility? If so, what would be the symptoms? I did check the oil, but the color was still healthy and thick with nothing milky.

Thoughts/suggestions?

Second question...if it does come to the need of getting a new head gasket, how would I know which is the right one for the engine I have under the hood? It is designated B18B, high compression type.

Thanks!!

-DS

Hey guys, many thanks for all of your advice/suggestions about the leaking coolant.

For sure, it is not leaking from inside the cab. The rubber floor was all cracked so I had all of it removed down to bare steel floors. And the heater valve was recently replaced too.

Right now the Amazon is up on jacks as I am in the process of replacing all of the suspension bushings and tie rods.

Once that is done, I'll go back to the coolant issue. Will keep you updated on what I find out and hopefully one or more of your tips would help pinpoint the cause.

Thanks again!

-DS

you could try pulling spark plugs, get a flashlight, and look closely at each piston... rotate the engine by hand.

If you seen an exceptionally clean piston, that would be indicative of coolant getting burned in the cylinder.

if all the cylinders look similarly dark gray or black.. I'd be looking under the carpets for evidence of a heater control valve leak.
--
-Matt I ♥ my ♂

Is there air in your cooling system?
You can tell by watching in the overflow bottle while squeezing the upper radiator hose.
If you get liquid movement the system is full.
If you get bubbles you have trapped air and it could be that the coolant is slowly replacing the air.
If that is the case you need to keep squeezing the upper hose until no more bubbles come up.
You'll have to replace the coolant as it goes down.
If it IS liquid full another place to look is your heater valve. It is on the firewall.
See where your 'Temp" control cable goes. It may be leaking and the coolant is soaking into the
jute backing under your rubber floor mat and rusting your floor.....

Hi all:

My 122s is finally back on all of its 4 wheels after the complete suspension overhaul (tough and dirty work replacing, but at the end, the poly bushings really felt awesome!!)

Walrus3: Seems you are right about the trapped bubbles gradually being pushed out from the coolant system. The coolant level from the expansion bottle is no longer dropping.

Others: Thanks again for all of your dropped-in suggestions. I'm filing them away for possible future references!

-DS

If coolant is getting inrto your oil you'll soon need more than a head gasket. Usually coolant will bead up on the dipstick and is pretty obvious. A large amount, as you describe, should be easy to see. If it's getting into the cylin ders firing chamber there should be some sort of telltale exhaust coming out of your tailpipe. There's only so many places the coolant can go-on the ground, into the oil pan, into a cylinder or into the cab. If you don't smell it, or find it in the oil or see smoke then it is probably on the ground, Try parking over a fresh, clean piece of carboard and check for any leaks that way.

That matches what happened for 2 years before my 740T's head gasket gave way completely.
You can test your coolant for exhaust gases with a kit from Napa. You can also use a dye kit to see if you are getting contamination between the two.

A phone call to FCP Groton will probably tell you exactly which gasket you need. Those guys are great, but it is an older engine. If they're not sure, I bet they'll find out for you, but you might also call Tasca Volvo. They both have good reputations on the board.
A lot of people swear by IPD, but I think their prices are outrageous and I don't buy from them.

Happy Bricking!

--
1990 740 Turbo, on its way to stock specs, maybe beyond