How do you do a compression/leakdown on 911?
 

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

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,.....:) :)

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?

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.

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.