Did a Compression test on gpx engine

[V6 Mivec Colt]

As some of ye may no i put a gpx engine into my colt.

engine was running fine before stripped the fto

Its not showing any signs of problems now either but just did the test anyway

got 15bar in all cylinders bar one where i got 10 bar

Any ideas why ?
Thanks

[CJ]

There could be a number of reasons for lower compression in one of the cylinders - either a value seat issue, a worn piston ring or a sticking piston ring. You'll need to undertake a wet compression test (squirt ATF into cylinder via spark plug hole) - if compression stays the same, its likely a value, it it increases then its a piston ring. There should be guides out there on the net for the process.

[V6 Mivec Colt]

What is ATF ? (automatic transmission fluid ) i doubt im right but what ia ATF

Also can a car run right and be healthy with lower compression in one cylinder or is bollixed ?

Thanks

[CJ]

Yes, Automatic Transmission Fluid. In terms of running, it depends. The engine will likely burn oil and there may be a noticable loss in power. If in doubt, bring the car to a good mechanic for a leakdown / wet compression test for a proper diagnosis.