Compression and Leak Down testing.

[Red97sc2]

I'm pretty clear about the compression test as far as what to do:
Pull Fuel Pump Fuse
Start the SL2 up (stalls immed - Ok)
Hook Up the gauge
Crank at least 10 revolutions.

Now, about a "Leak Down Test". What all is invloved with this? Is this something that I can do at home with the proper tools or does this need to be done at the dealer?

Thanks!

P.S. I did a search but all I came up with was " A leaky this" and " A leaky that".

[wolfman]

Probably not something you can do at home. In a "leakdown test" a regulated amount of airpressure is introduced into each cylinder and that pressure is monitored over time to see how fast it "leaks down". This indicates the overall sealing capacity (or lack thereof) of the cylinder piston rings and valve seats.

[davemac2]

You COULD do it if you want but it is much more involved than a simple compression test. You usually want to position the piston for the cylinder under test at TDC to start which means accessing the crankshaft pulley to do that from the right wheel well. A leakdown tester basically injects compressed air at a fixed rate into the cylinder via spark plug hole. A small orifice is inline with the air inlet which controls the rate of injected air. There is a pressure gage on each side of that orifice to measure the pressure difference which is proportional to the leakage in the cylinder.

You can make your own tester if you have a compressed air source: diy leakdown tester or you can usually buy one for $35-$60 (see EBay).

I personally would not do a leakdown test unless I have or suspect an actual problem like a potential head gasket leak, cracked cylinder sleave, bad valve or ring, etc. It's very useful to pinpoint a problem. For example, you have a V6 with 2 heads and you only want to pull the head that has the issue.

davemac