AD31P-A Compression test question

[GettinBetter]

Hi Peeps,
Have just compression tested the above mentioned engine, but am only getting ~215/220 PSI, any thoughts as to what they are supposed to be?

Many thanks.
Regards
GB

 

[Don S]

Re: AD31P-A Compression test question

Here is a copy and paste from the manual.

Cylinder pressure at starter motor speed 4 r/s (240 rpm) ... 2.5 MPa (25 kp/cm 2 )

 

[GettinBetter]

Re: AD31P-A Compression test question

Cheers Don, That's the figures I've got.....appreciate your prompt reply.

That 2.5 MPa converts to ~360PSI That's a big difference don't you think?

Turbo has virtually no play on the shaft, so I thought it was a low hours engine, perhaps its sticky rings, it runs nicely under no load.

 

[Don S]

Re: AD31P-A Compression test question

Put about a teaspoon of oil in each cylinder and do another compression test. If it comes up, the rings are bad.

 

[GettinBetter]

Re: AD31P-A Compression test question

Yes, thank you, I am familiar with that test and will proceed with it shortly, but assuming that the rings aren't worn beyond acceptable limits, and might be stuck in the grooves (through carbon build up & lack of use), it would show the same symptoms, don't you think?

I thought I might do an oil flush, and then put an additive in the oil & fuel to remove the carbon build up. It's a lot cheaper than a complete strip down. However if it doesn't increase the compression readings, then as you say they must be 'bad', or a combination of poor valve seating AND worn/broken rings. Maybe this engine HAS done more hours than I first thought, and has just had a refurbished turbo.