head gasket life?

[deeman940]

, did you retorque the head (by slackening each 1/4-1/2 turn then retorquing through entire procedure) after 600 miles when you retensioned the timing belt?

i didn't do the job but i know this wasn't done,,,,had no idea it needed to be..........

[Laird Scooby]

Originally Posted by deeman940

, did you retorque the head (by slackening each 1/4-1/2 turn then retorquing through entire procedure) after 600 miles when you retensioned the timing belt?

i didn't do the job but i know this wasn't done,,,,had no idea it needed to be..........

That could be the cause of the problem then. However if stretch-bolts were used it's not necessary but they have a different tightening procedure to compensate. Also if you didn't do the job you have no idea if the block bolt holes were cleaned out before the new bolts were fitted - again this can cause premature HGF if the threads are dirty in the bolt holes. Dirt/grit in the threads can cause false torque readings and the bolts will be nowhere near tight enough.

Lastly was anything mentioned about retensioning the timing belt? That needs doing regardless after 600 miles.

With the head bolts, if memory serves the hex head bolts are the non-stretch variety and the stretch bolts have Torx heads on them - might be wrong but failry certain that's correct.

[TonyS9]

Elring should be good quality, but at 18psi you are pushing things. With alot of duty (heat) you could be getting patches of boiling in the head with the extra heat, causing a lack of cooling. Especially if you have any pressure sealing problem in the system, or just the pressure is going beyond your caps limit. I use waterless coolant in my 360 B230FT because the cooling system design pressure is lower than than the 940s. I get hissing and bubbles in the system when using water.

I also had a small damage to the gasket probably caused by me when setting the head down. Then I have noticed that many old stock volvo gaskets are corroded, the oil in the package has attached the gasket.

I've also had problems where I made a mistake and used a multiple splined socket instead of a 6 sided socket to tighen. The socket then slipped mimicing the torque wrench. Luckily I noticed the coolant weaping before I started it, and then replaced the bolts.

The block or head may not have been properly cleaned or you might have deep corrosion pitting that wasn't repaired.

In other words it could be anything, running 18psi and higher than stock power level you need everything to be spot on.

[bgarston]

Originally Posted by Forrest

In my experience the original hg gives up at about 150k miles. I’ve not had a replacement fail yet. 1994 B200FT replaced at 145k miles in 2007 now on 278k. 1997 B230FK replaced at 157k miles in 2012 now on 227k.

Both still completely stock performance though.

I would echo this, my one was replaced at ~150,000 miles too a few years back. It's now at 180,000 odd miles.

[Clan]

Originally Posted by deeman940

i replaced the head gasket around 5 yrs ago shortly after i bought my 940. i used an Elring gasket with Elring bolts. It would appear it has gone again, is this normal? i would of expected to get a bit longer out of one but i know it is a known common issue...

Head gaskets on these are extremely high quality and long lived they don't just " go " You need to find out why , is it corrosion or perhaps overheated by coolant loss at some time ? In which case the head face AND often forgotten the block face need to be checked for flatness and use a new VOLVO gasket.

[griston64]

Originally Posted by Laird Scooby

That could be the cause of the problem then. However if stretch-bolts were used it's not necessary but they have a different tightening procedure to compensate. Also if you didn't do the job you have no idea if the block bolt holes were cleaned out before the new bolts were fitted - again this can cause premature HGF if the threads are dirty in the bolt holes. Dirt/grit in the threads can cause false torque readings and the bolts will be nowhere near tight enough.

Lastly was anything mentioned about retensioning the timing belt? That needs doing regardless after 600 miles.

With the head bolts, if memory serves the hex head bolts are the non-stretch variety and the stretch bolts have Torx heads on them - might be wrong but failry certain that's correct.

Pretty certain the standard head bolts are the stretch type on a 940 and new ones should be used every time. Three stage tightening 20nm,60nm and angle tighten 90 deg. Clean threads and oil bolts. No mention of re torquing

Dave is right that the belt should be re tensioned but I've never heard of a garage calling anybody back to do that after 600 miles

[deeman940]

Originally Posted by griston64

Pretty certain the standard head bolts are the stretch type on a 940 and new ones should be used every time. Three stage tightening 20nm,60nm and angle tighten 90 deg. Clean threads and oil bolts. No mention of re torquing

Dave is right that the belt should be re tensioned but I've never heard of a garage calling anybody back to do that after 600 miles

i wasn't aware of this at all...and never heard of it on any other car....is it because of the iron block/ ally head combo?

[griston64]

Originally Posted by deeman940

i wasn't aware of this at all...and never heard of it on any other car....is it because of the iron block/ ally head combo?

The bolt torque sequence or the re tension of timing belt ?

[deeman940]

Originally Posted by griston64

The bolt torque sequence or the re tension of timing belt ?

both!! but mainly the belt

[Laird Scooby]

Originally Posted by deeman940

both!! but mainly the belt

Because you didn't do the job yourself, don't know what sort of bolts were fitted. Early 940s had normal bolts that do need retorquing, later ones don't as previously mentioned. You really need to find out which you have.

As for timing belt retensioning, it's more common than you think.

For example, on my other beast, there is a special blue timing mark at ~18deg ATDC and that is where you intitially set the tension. Then you turn the engine over 2 turns by hand and check everything still lines up. If so, you start the engine, let it idle until hot, switch off and allow to cool. Then turn the engine to the blue mark just after #1 TDC and release the tensioner locknut and let it retension, tighten the locknut. That's it for the next 96k miles.

However on the redblock it has to be after 600 miles, timed at TDC #1, slacken the tensioner locknut and let it retension then tighten the locknut again. If memory serves that's it for 40k miles (early square toothed belt) or 50k miles (later rounded tooth belt) but the wise owner will use 36k and 48k miles respectively.

As for my 760, that's never had a timing belt!