How do you do a compression/leakdown on 911?

[axl911]

How do you do a compression & leakdown on a 911/930 since the spark plug is on the top side of the engine?

On a 964/993, it's easy to do it using the bottom plugs.

But on a 911/930, is it possible to use the flexible hose that normally come with the testers to screw into the sparkplugs hole?

thanks,
anthony

[Steve@Rennsport]

Hi Anthony,

While its not easy on some cars such as a 930, one uses the flex hose and install this into the plug hole. I usually do thing by feel since its tough to see anything,.....

[Jakkalas]

I have been told that in order to do a leakdown test, the engine has to be removed. Is this true? Or can a compression and leakdown test be done without removing the engine on a seventies or eighties 911?

[RSTarga]

I was under the impression that the leakdown should be done on a warm engine, so it would be almost worthless on an engine out of the car. A leakdown is to see where the leaks are, if it's rings the tolerances are wrong on a cold engine.

[LJ851]

You can do both tests in the car, it is not difficult. While a warm leakdown may be more accurate, a room temp leakdown on a removed engine is much better than nothing. Any substantial leakage will leak hot or cold.