New head cylinder now leaking coolant around gasket

[MoVolvos]

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I am not familiar with a 940 but it looks like the intake gasket could have possibility overlap into the T-Stat housing flange so you are torquing down in all practical purposes two gasket height compared to the other side. You will need to verify this either way by removing the flange per regent. Although you should not need too but a very thin film of RTV would not hurt but from the amount of coolant leak before and after re-tightening the screws your definitely have a large material wedge between the flange and cylinder head mating surface.

Blessings,

BKM

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[MoVolvos]

Sorry, but you were postings while I was writing my last comment. Most rebuilders require you to re-torque the head bolts after 500 or so miles. I don't remember exactly as it has been close to ten years since I purchased a rebuilt so go ahead and retorque but don't over do it.

Use factory torquing pattern and if for some reason it is loose do 1/8 of a turn at a time until each one meets the torque or set the torque wrench at a slightly higher torque setting and again not more than 1/8 turn till all are at that very slightly higher rating.

[regent]

If head bolts have not been re-torqued, then you have found your solution.
Factory pattern and method of tightening are indeed very critical. You want to double check to see if yours includes angle-torqueing.

[billofdurham]

Re-torquing is not called for on the 940. Stage 1 torque is 20nm; stage 2 is 60nm and stage 3 is additional 90 degrees. This should have been done when the new gasket was fitted.

If you do re-torque this is the sequence:

940 cylinder head bolts sequence.jpg (19.46 KiB) Viewed 1521 times

Bill.

[aisrael]

I have a similar issue.

I replaced the head gasket on my 93 244 a few years ago. The engine was overheating and leaking coolant in between #2 and #3. I has the head checked for any warping or cracksand I checked the block for warping or cracks.

My sister drove the car for a few years an now it leaks a little bit from behind #4. I am not sure if she overheated the engine with the A/C in the summer but I think she did not.

Would re-torquing the head be wise? If I should, what torque should i set it to?

Aaron

[MoVolvos]

I have a similar issue.

I replaced the head gasket on my 93 244 a few years ago. The engine was overheating and leaking coolant in between #2 and #3. I has the head checked for any warping or cracksand I checked the block for warping or cracks.

My sister drove the car for a few years an now it leaks a little bit from behind #4. I am not sure if she overheated the engine with the A/C in the summer but I think she did not.

Would re-torquing the head be wise? If I should, what torque should i set it to?

Aaron

If the cooling system can not be pressurized then overheating will occur. When pressure goes up so does the temperature or visa versa but the fan is able to reduced this in an enclosed system. When the system is opened the heat that is required to be removed by the cooling system is not able to be removed by the circulated coolant (PV=nrT). You may go ahead and re-torque BUT you have to remember THAT there is a GREAT, GREAT possibility of breaking the head bolt so that is a calculated risk you have to decide for yourself. I have re-torqued 3 cars. 88 Camry (220K) and 99 Galant (120K)for oil leaks and reduced both to a minimum so the cars were still usable. On a 95 Grand Caravan with a 3.0 Mitsubishi Motor which was drinking coolant (disappearing internally) it held up for about a year and was donated. It was not drinking coolant at the time. Again you need to decide whether you want to take that chance but if your cooling system is not holding pressure you will overheat and potentially warp a few things here and there.

Blessings,

BKM

PS If you do re-torque you may want to back it up an 1/8 of a turn before tightening. I would not go more than 1/8 of a turn to tighten or 1/4 turn) - (1/8 Loosen, 1/8 Tighten original position, 1/8 added torque) - MUST FOLLOW Torque Pattern!

[aisrael]

Thanks for the info. The engine only slightly leaks coolant ( maybe a couple of drips or so). I think I will pass on the retorquing and I will wait unitl it really leaks.

Aaron

[donis222]

FYI:
The new style stretch bolts that are tightened by turning X amount after a min. torque do not need retightening. This advantage is the reason that this style was addopted. The old style with a specific torque setting, benefit from a retorque

[rgk]

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