Poss head gasket

[marinabrian]

Originally Posted by WillyHeckaslike

The OEM gasket was modified and supposedly strengthened. Many holes were made in the metal base sheet so that the silicone beads on each side were attached via molding to each other directly. The characters involved in this development were, like their creation, not fit for purpose. The silicone beads in many engines still dissolved and turned to goop and became detached or disappeared in part, some in very short order and others not so. Any competent engineer would have looked for the common denominator. Fists full of paper and empty heads, perhaps?

I wonder what went wrong with my 214, after all 397,000 miles without having to take the head off

After I've dispensed with the wife's 75, I'll be pulling the head off the 214 as I'm curious to see what the bores look like after 370,000 miles of running on LPG.

MLS gaskets require the block landing surface and head face to be machined and there to be no annealing to have taken place, i.e. when the liners are hammered into the block after picking up on the pistons during a serious overheat, and "drop" a misnomer which does not convey the severity of the damage that has occurred.

I have used MLS gaskets in the past with mixed results, however I won't use anything other than a Payen BW750 for any job, irrespective of liner protrusion

The trick as Guido pointed out earlier is to tighten the bolts to the 20NM preload, make a cuppa, then to slacken in sequence by an 1/8th of a turn then retighten to 20NM.

If the bolts are original, they have two lines on the head, this mark needs to transposed onto the head with a marker pen or similar, then the final tightening sequence carried out rather than two half turns, four quarter turns.

After all ten bolts are tightened correctly, the marks on the bolt heads will align with the ones made on the head.

And use blue antifreeze, not red

Brian

[kaiser]

I have just pulled a head gasket on one of our Fs. The beads of silicone hangs like lose strands of spaghetti! The car is 2002 with 51000 km. Well maintained! Obviously a matter of age rather than wear. The car never overheated, just mixed water an oil. I will see if I can find a picture!



and here is a picture of the newer gasket with improved strands.



It is not so much a case of the silicone strands dissolving. Rather a problem with adhesion, it appears to me.

[Lovel]

Originally Posted by kaiser

It is not so much a case of the silicone strands dissolving. Rather a problem with adhesion, it appears to me.

Nobody mentioned that the silicone dissolves. It’s the bond between the steel and the silicone that fails.

If only the manufacturer had perhaps cut a series of dotted lines right through the steel part of the gasket with a laser before the bead is laid down. I believe this would have significantly improved the adhesion of the silicone.

[marinabrian]

Originally Posted by Lovel

Nobody mentioned that the silicone dissolves. It’s the bond between the steel and the silicone that fails.

If only the manufacturer had perhaps cut a series of dotted lines right through the steel part of the gasket with a laser before the bead is laid down. I believe this would have significantly improved the adhesion of the silicone.

That and OAT turning the elastomer into chewing gum

It doesn't happen with blue antifreeze Gary

Brian

[kaiser]

Originally Posted by Lovel

Nobody mentioned that the silicone dissolves. It’s the bond between the steel and the silicone that fails.

If only the manufacturer had perhaps cut a series of dotted lines right through the steel part of the gasket with a laser before the bead is laid down. I believe this would have significantly improved the adhesion of the silicone.

The silicone beads in many engines still dissolved and turned to goop and became detached or disappeared in part, some in very short order and others not so.

This is how I understood this.

[T-Cut]

As of 2004, the gaskets hadn't been 'improved' in any way I can see. The elastomer (is it silicone, or something else?) simply peeled off the metal exactly as seen (yet again) in Kaiser's photo. The are many HG failures with exactly the same cause.

As for the OAT debarkle. I'm waiting to see the effects of 50% OAT on the elastomer that peeled of my own gasket. Obviously, immersion in OAT at room temperature isn't the same as the hot/cold environment of an engine, but if there is a chemical instability, it WILL show eventually. Chemical reaction rates double (approx) for every 10°C rise in temperature, so given enough time, if OAT dissolves/plasticises/etc the polymer used here, it will become apparent. After six months I see no effect. My feeling thus far is it's an adhesion problem. Perhaps OAT compromises the adhesion bond energy rather than the polymer itself? I bet Kaiser's engine (above) didn't have OAT in it??

TC

[kaiser]

Originally Posted by T-Cut

As of 2004, the gaskets hadn't been 'improved' in any way I can see. The elastomer (is it silicone, or something else?) simply peeled off the metal exactly as seen (yet again) in Kaiser's photo. The are many HG failures with exactly the same cause.

As for the OAT debarkle. I'm waiting to see the effects of 50% OAT on the elastomer that peeled of my own gasket. Obviously, immersion in OAT at room temperature isn't the same as the hot/cold environment of an engine, but if there is a chemical instability, it WILL show eventually. Chemical reaction rates double (approx) for every 10°C rise in temperature, so given enough time, if OAT dissolves/plasticises/etc the polymer used here, it will become apparent. After six months I see no effect. My feeling thus far is it's an adhesion problem. Perhaps OAT compromises the adhesion bond energy rather than the polymer itself? I bet Kaiser's engine (above) didn't have OAT in it??

TC

You lose that bet T -Cut. We bought it off a lawyer that had it maintained by an authorized MG-dealer until it went to an enthusiast garage. They followed the service plan to a T. We bought it exactly because it was so well maintained. Did about 500km in it, and the gasket went. That is one of the problems with these cars, the other is the suspension system, which I re-built. Now it drives as new, again! Except for old fashioned anti freeze!!
And, just to add, there was a lot of "gravel" in the radiator. I got about two or three spoon full of rust like coarse sand, after flushing the radiator. The temperature dropped by about 20 degrees on the oil temperature and went from slightly over middle to slightly under on the water!!
I guess that rust came off the liners?

[Lovel]

Originally Posted by kaiser

You lose that bet T -Cut. We bought it off a lawyer that had it maintained by an authorized MG-dealer until it went to an enthusiast garage. They followed the service plan to a T. We bought it exactly because it was so well maintained. Did about 500km in it, and the gasket went. That is one of the problems with these cars, the other is the suspension system, which I re-built. Now it drives as new, again! Except for old fashioned anti freeze!!
And, just to add, there was a lot of "gravel" in the radiator. I got about two or three spoon full of rust like coarse sand, after flushing the radiator. The temperature dropped by about 20 degrees on the oil temperature and went from slightly over middle to slightly under on the water!!
I guess that rust came off the liners?

The rust may have came from the twin mild steel pipes that run the length of the car especially if anti corrosion agent not used or weak mixture, the hot and cold cycling might increase this outcome.

[T-Cut]

Originally Posted by kaiser

You lose that bet T -Cut. We bought it off a lawyer that had it maintained by an authorized MG-dealer

Ah OK. I assumed it was one of your own. I believe you're not a fan of OAT.


TC

[WillyHeckaslike]

Originally Posted by marinabrian

I wonder what went wrong with my 214, after all 397,000 miles without having to take the head off

Good question and no doubt there are others too but I'm not sure that your case forms a part of the majority Brian. An equally good question to ask is, what went wrong with my 75 and many other K-series engined cars which failed like it. It came to me with HGF, on removing the head I could see that the gasket was not oem so it was not the first time this had happened. A lot of the silicone beading was missing and what was left of it was like very soft and slimy spaghetti - or goop as I would describe it. It was the type of gasket as shown by Kaiser, his new replacement one. This type of gasket does have the holes in the metal base sheet as Lovel mentioned, I could see them in the failed gasket on my 75 where the silicone beading was no longer having been dissolved and swept away.

My 75 aside, with the oem gasket where the silicone beads are bonded to the metal gasket surface only and not to the beads on the other side via holes in the metal gasket surface, why would any bonding failure be a problem after correct assembly? Many seals gaskets and o-rings in many applications rely on compression only so once the silicone beads of the head gasket are under compression they are not going anywhere. So why would they fail? Unless, maybe, the silicone material is somehow softened and gasket compression is lost as a result.

Yes, I am aware that incorrect assembly and insufficient attention to detail can play a part in HGF but it does not explain every failure. Some failures have been reported where a head gasket had not been touched since it left the factory and the car was dealer maintained. Some very knowledgeable and able enthusiasts have also reported repeat failures.