Leakdown tests

[expat]

So I don't labour this board with previously asked questions, besides using the search tool that often doesn't get to the heart of what I'm looking for, can someone post any links for technical/repair work on 87 911's.

Currently I'm looking for how a leakdown test is conducted and what the readings could be and how to assess/understand the readings.

Thankyou for your help.

Cheers
Mark

[patalive]

Mark, here are several links to the PCA Potomac BBS on Leakdown tests. You might also want to do a search of this BBS and perhaps Rennlist as well.
-
Good Luck!
Chuck

http://www.pcapotomac.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=2&t=001495
-
http://www.pcapotomac.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=2&t=000982
-
http://www.pcapotomac.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=2&t=000525
-
http://www.pcapotomac.org/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=2&t=000451
-

[Jerry S]

I could be mistaken, but if results as high as about 40 % were present on at least a couple of cylinders and this test were totally valid than would the car even run ? And if so does one think that there would be any power ?

I really question the validity of this test. I think a good compression test and road test tell the story.

Thanks Jerry S

[Superman]

I won't describe it since the links probably do, but this test takes a while and should be repeated if there are any problems indicted. Do it warm, and drive the car between tests.

The thing this test is good for is isolating what is wrong with a cylinder. Take the CAT (if equipped), the oil filler cap and the air filter and cover off. When a pressurized cylinder is leaking, the noise will be at the air filter (intake valve), the exhaust pipe (exhaust valve) or the oil tank (rings). Use a piece of garden hose to listen.

On my last leakdown test, one cylinder (not the one with the broken head stud) leaked 38% The car runs strong, and makes 192 psi on a compressin test, on all cylinders basically. So the point is, don't put much trust in a leakdown test. Especially a single test.

------------------
'83 SC

[twin plugged targa]

Interesting to hear that Superman especially cos the P mechanic who 'Had' my car said that a cylinder had 20% leakdown although he did no other cylinders and no compression test!! .
I removed the car from his garage, paid the $1000 bill and fixed the car myself.
Incedently the car burns no excessive oil, no smoke on start up or driving hard!.
She goes like a cut snake!.
So much for leakdown tests!.