Compression Test Results

frostphase · Sep 10, 2014

So I performed a compression test on this 2G 420a

160 - 165 - 160 - 140

Then I performed a wet test on #4 and got 180 on the gauge.

So is this definitely bad rings? I was really hoping it would be something simpler like valve stem seals...

I get some light blueish smoke during idle.. sometimes, not all the time..

What do you guys think?

bryanwheat · Sep 10, 2014

Impossible to tell without doing a leakdown test. The smoking could be from valve seals, but the low compression is going to be either rings or valves.

frostphase · Sep 11, 2014

Would pouring a capful of oil in the #4 / 140psi cylinder be considered a "leakdown" test? It shot up to 180psi after doing so..

bryanwheat · Sep 11, 2014

frostphase said:
Would pouring a capful of oil in the #4 / 140psi cylinder be considered a "leakdown" test? It shot up to 180psi after doing so..

No, that is a wet compression test. A leakdown test involves pressurizing the cylinder and finding out where the air is leaking from.

BALLAPYTHON · Apr 27, 2015

What should the compression be of a 420a?

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Compression Test Results

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