Along the lines of PureEnergy's post (earlier today), I just performed a compression test on my 1996 850 Turbo w/auto trans and have some concerns/questions about the compression numbers. Test parameters: Warm engine, all plugs removed, fuel injectors disconnected and coil disabled.

Cylinder #1: 137
Cylinder #2: 137
Cylinder #3: 137
Cylinder #4: 138
Cylinder #5: 139

It took 40 engine revs (approx), per cylinder, to attain these numbers. Call me crazy, but seems way too long. I then added a couple squirts of engine oil into each cylinder and re-tested...not much difference:

Cylinder #1: 140
Cylinder #2: 142
Cylinder #3: 140
Cylinder #4: 141
Cylinder #5: 140

Volvo says the pressure should be: 156 - 185 psi.

Except for weak "off-the-line" performance, the engine runs great with overall MPG of 21. Idle is perfect, revs freely and does not smoke, although I am adding 1 quart of oil every 3-4 weeks. I have replaced all the ignition components, induction hoses, belts, vacuum lines, coolant and hoses, recent oil & filter change, and replaced trans fluid. I am using dino oil because I have not replaced the slightly leaking oil cooler hoses yet. Once done, I plan to use Mobil 1. All sensors are OEM and appear to be working (no MIL).

What conclusions can be drawn from all of this? I appreciate whatever suggestions anyone can offer.

Greg

You should also check the seal at the rear of the camshaft!!!

All seals are intact, nor are they leaking or weeping. The breather system is working properly. Were you trying to confirm an intake valve leak?

Nothing wrong with your rings! I do suspect that something could be wrong with the tester itself, it shouldn't take that long to test compression. It only takes 2 revolutions to reach TDC for all 5 cylinders.

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My name is Klaus and I am a V♂lv♂holic

Thank you, Klaus. Are you also suggesting that the compression tester is giving a false (low) reading?

Greg

Yes, there appears to be a fault somewhere as you didn't get a 'good' reading until you turned over the engine a bunch of times.

So long as the timing marks line up correctly, a pain to check, all 4 valves should be closed at TDC. If you are 1 tooth off, that could present a problem as the engine timing will correct for that discrepency after a number of rpms.
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My name is Klaus and I am a V♂lv♂holic