Yep another Engine Rebuild I think?

[Gary71]

...all cylinders having poor compression means they all have a problem and most likely the same problem.

...or the measurement method/tool used for all of them is wrong and there’s nothing wrong with the basic engine.

[fetuhoe]

...all cylinders having poor compression means they all have a problem and most likely the same problem.

...or the measurement method/tool used for all of them is wrong and there’s nothing wrong with the basic engine.

Unlikely as the differnece between 50 an 100 psi is very significant and does suggest a fairly serious probem.

If the gauge is a screw in type and the engine was cranked for long enough to stablise the reading any errors will be small an even 1000 psi is very poor.

Een with the throttle closed the only real difference in reading is likely to be the number of revolutiones needed as air will still draw through the idle by-pass circuit.

With a WOT the number of revs needed to stabalise the reading does give some guidance but peak compression values won't be as low as 100 or 50 psi.

The last engine I saw with a cylinder at 50psi had a broken Dilavar stud and the CE ring was 80% burnt out and the top of the cylinder was damaged.

The engine had been run with a broken stud for quite some time and the oil leak at the base of the cylinder had neen building up for years.

If the engine is still connected to the transmission you could put it onto a pallet and do a cold compression test by connecting the starter to a battery with jump leads but if you are confident in your readings I would just take off the heads and find out what is going on.

50 psi means that even if you do a leak down you will need to take some action.

[jaymatwhit]

Gents, many thanks for all the great replies and in depth advice. Just wanted to let you know I am not ignoring you and will take it all on board but as of right now I am a victim of the Carillion CRIME and need to focus on that but I will return.
Many thanks again, Jason

[tim69s]

Hi, did you get to the bottom of the problem with your engine?
Is it a rebuild?


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[jb]

Is it possible that you over-filled the oil when you changed it?

[jaymatwhit]

Sorry guys been run off my feet.
Basically gasket failure but no idea why (faulty batch?) and stopped wasting time trying to find out just rebuilt top end and as good as new again

[abzadams]

.
Basically gasket failure but no idea why (faulty batch?) and stopped wasting time trying to find out just rebuilt top end and as good as new again

Exactly the same for me last year.