Compression Results - How bad?

77 'S' ~100K miles, no engine work done to date as far as I know.
>
> Cyl # Compress
> 1 149
> 2 111
> 3 156
> 4 140
> 5 139
> 6 146

Any opinions?

[rob911]

Have a search. seen lots of advice recently, didn't really take any of it in - no compression tests for me untill all the friggin rust is gone.

.....mmm techron? and carbon in valves rings a bell.....

[StuttgartDavid]

1. Adjust valves - check for broken head studs at this time
2. Drive car
3. Retest

4. If #2 is still low, ask yourself: "How do I intend to use this car?"
Many possible answers will not require a rebuild. 110 psi is not zero. Performance and mileage will be down, but not by 1/6 (16%), but instead only by a fraction of 1/6 (closer to 5%, I would guess).

5. Also ask: "Is that one cylinder visably leaking oil or combustion gas from head or base of cylinder? "Do I have a broken head stud, etc. ?"

Depending on answer, then ask yourself: "Can I sleep at night running an experiment to see just how durable these engines are, knowing I very likely could get another 5+ years and 50k+ miles even if I do nothing now except drive it, or would my life and/or finances be ruined if it did suffer catastrophic engine failure, which is possible, but less likely."

Be honest with yourself, then decide and act (or don't act . . .)

I know the studs are fine. Loose nuts were the original reason for opening the covers. All were below torque spec, a couple were only finger-tight, 2 were off the studs.
#2 (the low one) has leaked some oil at the head end.
Valve adjsment completed before compression test.

I've told the shop to button it up and work on the cold-start problem.

[JDaniel]

Are these results from a test you performed, or from a knowledgable shop?

A reputable shop with years of Porsche experience and the mechanic owns a 911.
Check thread
http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=57623
for more of the tale.

[Jdub]

well not quite. But it brought a pesky #1 back from 17% leakdown to 7%.

20oz in empty tank, fill, drive like you stole it, @1/2 tank refill, and continue "spirited" driving. By this I mean you take that car out for about two hours of driving to heat the engine up, not just the peripheral, but a full down-to-the-core heatup.

Dump oil afterwards and refill as Techron will drop the now-dissolved deposits into the oil (some to atmosphere).

This worked very well for me. I think that, with your headstuds torqued and a valve job behind you, you will reap the benefits of this colonic.

John

[Superman]

Now that I have said all the comforting things (on the other thread), her's some other stuff to think about: I believe JW said that the 2.7s would get warped cases, cylinder, heads, etc over time particularly if head studs were loose. He said retorquing may be a temporary thing. If the head/cylinder mating surface is not flat, the head studs will work loose again. In a worst case scenario, the may be working their way out of the case (pulling threads with them). So, they are worth keeping an eye on.

If it were my car, then I'd drive the car, flogging it mercilessly on quiet stretches of county road, until the next oil change. At that time I would check valve clearances and head nuts BEFORE removing spark plugs. Then I'd remove the plugs and do another compression check. After all this, you will have a great deal more information about the condition of your engine.