Hi all,
I am working on a Rover 25 K-Series engine, when the car was brought into the garage it was pressurising from the oil filler cap (or rocker cover).
A compression test was carried out on the engine just to see what figures we were getting NO 1 cylinder:40psi, No2:55, No3: 35, No4:120 - Something was evidently very wrong with the engine.
With the k-series engine being notorious for a dodgy head gasket, we took off the head and found that it did require skimming and a new head gasket. Before fitting we checked the bores and pistons which were fine.
The proper head gasket was fitted, new stretch bolts were added and the engine was timed up.
Following build up the car refuses to start (even with a pull).
Another compression test was carried out - all figures were less than 50 psi (should be around 120 - 150psi).
A tablespoon full of oil was put into each cylinder, and a compression test was carried out - all results were above 120 psi. (you may be thinking what we were thinking - piston rings).
Before taking the engine out we looked at the problem in greater detail - and unfortunately found that the plastic oil level indicator fitted to the bottom of the dip stick has been melted off - Indicative of an engine which has been running in boiling oil (i.e a cooked engine).
Sorry for the long introduction - my question is:
Is it worth installing new piston rings into the engine to see if the compression returns, - the engine was running when we picked it up (albeit with very low compression), or once an engine has overheated is it useless?
I.e, I don't want to throw good money after bad, but on the other the other hand I am quite prepared to carry out the work if the engine may run again with no other problems
I would also be interested to hear from anyone who has fitted new rings to an overheated engine and found that it cured the problem.
Any information would be greatly appreciated
Many Thanks,
Stephen Laughlin
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When you said cooked,my thoughts went straight to distorted bores/block,they are intollerant where severe overheating is concerned.But IMO a new engine is in order or recon
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Steve
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Surely if it got hot enough for the oil to melt the dipstick plastic, it will have melted seals, gaskets and other plastic parts of internal assemblies.
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Steve,
Thanks for your advice, unfortunately I have no way of knowing how serious the overheating was. The bores do seem fine, another point is that the cylinder liners are wet i.e they can be changed relatively easily.
Its a difficult call.
Stephen
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If the oil has been boiling, undoubtedly the following bearing surfaces will be damged: oil pump, valve stems, main bearings, conrods, camshafts,etc. The damage may be minimal but it has probably started. if you rebuild the engine again, its life will be limited and performance down and oil consumption up.
Why bother?
madf
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Ive had one that was cooked and the pistons and bores when they had cooled down and been inspected were found to be oval.
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Definately a new engine. This one will almost certainly let you down again in the near future.
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When you say you checked the bores, do you mean you just looked at them, or measured all sections with an internal micrometer and compared with the maker's figures?
People did that in the old days, but I think now they just throw it away and get another one from a breaker.
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It is not so much the bores you have a problem with, more the pistons. Pistons are made of relatively cheap and soft alloy which has a surprising low melting point. When the engine gets really hot they expand in the bores and go tight. This damages the pistons and the rings. When they cool down again they are often distorted.
To be honest, with a K series, I would just scrap it. In fact the car can't be worth much can it?
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If i was you i will just bite the bullet and get a recon engine or buy a spares/repair rover with a good engine and do a complete engine transplant
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"If i was you i will just bite the bullet and get a recon engine or buy a spares/repair rover with a good engine and do a complete engine transplant "
And then sell the damn thing.
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did you have the head crack tested? if its been boiling i would have checked that,
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Thanks for the responses guys, pretty conclusive then - new engine!
Stephen
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