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Blown head gasket.


Paddy
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S111 2.25 diesel, got a blown head gasket for no apparent reason :( , what would cause it? The heads off and shows no damage other than a piece of gasket has 'gone' between two cylinders. Valves, rockers and push rods look ok. What else should I be looking for before re assembling?

regards

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I would suspect head warping, either due to overeating or not being torqued down correctly when last fitted.

Before re-fitting get it checked, and if necessary skimmed back to true if that is permissible on the diesel engine. Maybe worthwhile checking the block too, they do warp slightly after a few decades!

When re-fitting make sure the head & block surfaces are perfectly clean.

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I would suspect head warping, either due to overeating or not being torqued down correctly when last fitted.

Before re-fitting get it checked, and if necessary skimmed back to true if that is permissible on the diesel engine. Maybe worthwhile checking the block too, they do warp slightly after a few decades!

When re-fitting make sure the head & block surfaces are perfectly clean.

As above, and also check between the cylinders for cracks in the head and block.

Bill.

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I had a head gasket fail, between 3 and 4 cylinders shortly after my engine rebuild. Everything was skimmed and faced during the rebuild, and the engine had been carefully assembled on the bench.

Mine is a petrol, but the same theory applies. The diagnosis at the time of my head gasket failure was that a copper gasket caused the problem. After the failure I replaced it with a composite head gasket. I did not get the head or block reskimmed again, but I did give them a good clean and made sure as far as possible that there were no obvious imperfections.

5000 miles on, she seems to be fine.

I think that the deisel has a different gasket to petrol? so make sure you get the right one.

Betsy%20blown%20head%20gasket%20002.jpg

Betsy%20blown%20head%20gasket%20006.jpg

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Thanks lads, I'll get it checked for warping. My gasket is near identical to Betsy's so I hope its as simple as just a replacement. I'm just about to start a new thread looking for a parts catalogue if any one can help?

regards

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Black smoke billowing out, 'missing' on 2 cylinders and no power (alright, a lot less power) You'd also maybe find oil in radiator water or water in your oil.

Blue smoke is indicative of burning oil, bores, rings, valve guides or seals maybe)

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Thanks! I was sure it was the valveseals so I replaced them. No improvement....

But while pressurizing the cylinders I noticed bubbling in the adjacent holes for the removed head bolts. (they ran full of oil)

Which make me wonder if this is how the oil gets into the cylinders....

There is no blowtrough in the engine.

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sorry Shinais I'm no expert, hopefully the old hands will respond or you may need to start a new thread. I guess you'll need to be methodical though. If you can do a compression test that will show up worn rings/bores/valves or at least point to which cylinder/s are at fault. You've head the head off before so know your way round, it would only be a mornings job to take the head off and replace the gasket. Double check the head while off for valve wear on the guides, make sure the valve seals are the correct ones for the inlet or exhaust. another S111 I had gave a puff of blue when on overrun, this got progressively worse over the months and turned out to be 2 pistons oil scraper rings sticking in the groves, re ring solved my problem.

regards

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Thanks paddy! Stuck scraper rings might be the answer.

The blow through is so low that, even if I haven't done any compression test, I feel pretty sure that the comp.rings and bores are ok.

I run the engine without the manifold and couldn't see any difference between the cylinders, smoke seemed to be evenly distributed.

Valveseals came from Paddocks in two different bags, one of them marked "out". But I couldn't really tell any difference by looking at them...

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re valve seals. One has a 'coiled spring' running round the outside top ridge, I think these are the inlets, but its in the manual. An old hand told me to drop the sump and spray kerosine up into the bore/piston to free the oil scraper rings, it didn't work for me but you may want to try IF that is your problem.

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The seals came from Paddock, two plastic bags with 4 seals in each. One bag was marked "out". However, I could not tell any visual difference between them. All had springs. Same with the original seals, all with spring. Couldnt tell any difference between them either..

All were pretty worn so I was sure this was the cause of the smoke. But to my disappointment, exactly the same amount of smoke. :huh:

Haven't heard about kerosene, maybe you can drain the sump, fill with kerosene and turn it for a few minutes on the starter with glowplugs removed..?

If everything fails there is a wide choice of snakeoil available. :D

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Redex is/was the favourite snake oil - a few cc down each plughole reckons to free rings and soften carbon deposits.

Not sure whether it is OK in diesels, see what it says on the tin.

There could be a problem using kerosene on a diesel engine, if it gets past the rings into the upper cyclinder it could cause the engine to run out of control.

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Redex is/was the favourite snake oil - a few cc down each plughole reckons to free rings and soften carbon deposits.

Not sure whether it is OK in diesels, see what it says on the tin.

There could be a problem using kerosene on a diesel engine, if it gets past the rings into the upper cyclinder it could cause the engine to run out of control.

not fi the glow plugs out their wont be any compression its basically just turning it over to oil it up

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not fi the glow plugs out their wont be any compression its basically just turning it over to oil it up

Yes, but then you run the engine to expel the crud. Also part of the Redex treatment is to feed a trickle of redex into the carb when the engine is running, this could have implications on a diesel engine in that the engine could over-rev.

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Yes, but then you run the engine to expel the crud. Also part of the Redex treatment is to feed a trickle of redex into the carb when the engine is running, this could have implications on a diesel engine in that the engine could over-rev.

And you'd have trouble finding the carb ;)

I believe these days they have dropped the "pour it down the carb" idea and just recommend sticking it in the tank.

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