The saph has been parked up for 18 months and has now gone to the garage to get it back on the road All the fluida and filters have been changed and from cold ot starts and funs perfect BUT when it gets hot number 2 and 3 cylinders drop out, the garage has done a compression test and when the engine is cold all cylinders are as they should be but when hot number 2 and 3 are done to 20 psi. does anyone have any ideas for me to pass on

 

Anyone ?????

 

try a leak test.

 

All fluids are fine

 

No you trumpet, a cylinder leak test, to see if all the valves are opening and sealing correctly.

Good luck with your findings.

 

When you say fine, do you mean that from cold they are 140psi+ and then when the engine gets warm they drop to 20psi?

Dry test in both cases?

 

also maybe worth dropping a LITTLE oil down the plug hole when warm and do compression test?

 

Was my next question, if so, doesnt sound good.

Definately cylinder leakage test needed as well.

Then it looks like its off to a specialist by the sound of things for a professional diagnostic.

 

CHIP when cold ALL are at 140psi when hot number 2 and 3 drop down to 20 psi the car ran fine before it was parked up

 

Well effectively the only things likely to cause low compression readings are basically:

Inlet valves not sealing
Exhaust valves not sealing
Head gasket blown
Pistons melted
Rings broken up (just worn out wont do that)
Block cracked
Head cracked



Given the fact its two adajacent cylinders and they are dropping to the same value, that makes it seem likely they are ending up connected together, so either head gasket or block or head.

Of the 3, the one that sounds most likely to be effected so much by heat is the block, but this really is guesswork without more info.


First thing I would do is a leakdown test, if you do it with the cams removed it will mean that you can see if the air from cylinder 2 is coming out the plug hole on cylinder 3 when you do it, this would confirm its one of those 3 options in terms of connecting them together with a crack or block gasket.

 

Bob, what garage has your car out of interest??