compression test help!!

[kylaris]

I've got s13 sr20det black top just recently and trying to test compression.which is easiest way to check the compression?turning the crank or jumping the starter?and to jump the starter, how do you jump it? I tried to sorce + to the line and use the transmission as -, but didn't work well.

thanks,

[DAEDALUS]

You mean the engine and transmission are on a stand off the car? You can't get a good compression reading turning the crank by hand. You may or may not get a good reading with the starter if the engine is cold. If the transmission and engine are grounded your method should have worked I think...maybe there's a solenoid that needs to be switched on or bypassed? Make sure all plugs are out and the TB wide open.

[BadMojo]

Are you trying to compression test an engine that's not in the car yet? When you say turning the crank, do you mean by hand? If so, there's no way you're gonna turn it fast enough to get anything close to accurate results.

Edit: Doh...Daedalus was too fast.

[kylaris]

yes the engine and transmission are out. they are sitting on a crate.By turnning the crank, I've got it up to 115psi.

[DAEDALUS]

zzzzzzzzzzzzzzzzzzzzzzzing! Typy fingers on crack!

Unless you can spin it as fast as the starter, it's no good. Another option is to do a leak-down test. No starter needed, just the tester and shop air supply.

[BadMojo]

Unless you can spin it as fast as the starter, it's no good. Another option is to do a leak-down test. No starter needed, just the tester and shop air supply.

I don't think you could spin that sucker fast enough with all the air tools in the world, anyway. Daedalus, isn't a leakdown test considered to be a better way to check engine health anyway?