compression figures on a cold engine

[mike 850]

anyone done this, i know your supposed to do it on a warm engine and the figures will be lower but just seeing what people get, just did might and it was about 102psi on all 5 no difference in any which i think is what i need to look out for?

[Ettienne]

Mine have always been 160-175, obviously all plugs out and full throttle when cranking on a good battery

[stribo]

Obviously you want the same sort of figure across all the cylinders, from what I've read your looking for 150+, but not sure if that's on a cold engine, and whether or not you should do that dry, or with oil in. I'm sure someone who knows more than me (not difficult) will be able to advise the correct procedure. :)

[mike 850]

just warmed in up and it was still 100 but noticed the cheap pos tester i just bought seemed loose on the snap on connector, put some tape on it and got 125 but think its still leaking, just jbwelding the mofo and will try again

[oblark]

!50+ psi would be on a warm/hot engine with no oil in the bores,

You would only add oil if you had low readings and the oil would confirm if the low compression was rings or valves.

A cold engine engine should be 100+ psi

[mike 850]

Well added oil and readings went up to 175, don't know why as I had the bottom end checked out before having the rods fitted about 2k ago, bugger

[Ettienne]

!50+ psi would be on a warm/hot engine with no oil in the bores,

You would only add oil if you had low readings and the oil would confirm if the low compression was rings or valves.

A cold engine engine should be 100+ psi

My engine we changed, had 140, 150, 165, 165, 170 cold it sounded good and ran fine but 150 iirc is the tolerance and we had to take box out.

The new one cranked over 160 cold, but that had been sitting 7 years, I should do a comp check again now it's up and running.

[oblark]

The me7 engine I had from you cranked over cold at 120 psi across all cylinders.

[mike 850]

Well, spoke to the guy who fitted the rods, he thinks a hone and new rings will sort (i thought he honed before but it was just a clean) any ideas of the best place to get rings from, i hear Volvo dont do them anymore? Im assuming that because adding oil and the results dramically change the testing equipment is ok and it is the rings

[oblark]

Jamie at partsforvolvo

[mike 850]

Cheers mate, are they what you are using?

[Ettienne]

The me7 engine I had from you cranked over cold at 120 psi across all cylinders.

I had mine on the booster pack as well so may spin a bit faster.

[mike 850]

Did a hot test today, results were

Dry 105 105 120 115 105
Wet 140 140 155 145 135

So I can be pretty certain the rings need sorting, the more oil I put it the higher the compression went up, when sorting the cylinder head last year I spent a fair bit of time lapping the valves in so better start stripping the engine again