Morris Minor Owners Club

Hi,
I just did a compression test on my engine, just out of interest. The engine was fully rebuilt a year ago and when I measured the compressions then, they were 165-170. Today the tester read exactly 150psi on all cylinders. I should mention that different compression testers were used on each occasion. The question is, is it possible that my compressions have actually decreased or is it more likely to just be discrepancy between the two testers?


Thanks,
James

Compressions wil only go down, all things being equal, after the engine has been run in properly.

That said, compression testers are not that accurate. What you are looking for is the same compression on all cylinders, which you have.

Could even be down to the starter motor or battery condition, who knows! Stop worrying and bothering on those results.

RAB

Yes - the compression will have fallen away slightly - but it would be better to use the same tester, and same hot engine/throttle wide open/valve gaps set to 12 inlet/15 exhaust before testing.150 psi is 'ok' but not great.........