Low compression result on 83 SC

[asgi99]

I have an 83 SC and just had the compression tested by a Porsche mechanic. The readings are,

160,160,155,130,155,160

The mechanic said that I should keep an eye on the cyclinder with low compression but that it should not be a cause for worry. The car has 131k miles and has been serviced regularly over at least the last 12 years. It has better acceleration than other 83's that I have drove (it has Permatune ignition which may have something to do with this).

Is there a recommendation for next steps? Given that the other cyclinders seem fine, is this something that needs to stay as it is or can it get worse without greatly impacting performance? Is there an incremental approach I can take (i.e. start small and cheap)?

Many Thanks



Ash

[konish]

Drive it hard for a few miles, then do another check. Could be some carbon holding the exhaust valve open a bit.

R/
Dustin

[makaio]

What Dustin said. I find the harde I drive my 911's, the better they run.

[asgi99]

This is exactly the kind of advice I want, not that I need encouragement to drive it hard.

[anthony]

On the next compression check you can have the mechanic do a leakdown test on that cylinder to determine exactly where it's leaking from.

[jm529]

get them to check the valve clearence or adjust the valves on that one cylinder, it might be too tight. even at 130lbs that cyclinder will still fire and you shouldn't even notice it.

[cgarr]

Originally posted by anthony
On the next compression check you can have the mechanic do a leakdown test on that cylinder to determine exactly where it's leaking from.

Or if you just want to find the leak YOU can hook up your aircompressor to that cylinder when at tdc and listen which end the air comes out, intake, exhaust or crankcase!

Craig