C5 compression test! Help!
Thread Starter
Burning Brakes
Joined: Dec 2001
Posts: 1,190
Likes: 0
From: Jonestown, TEXAS
C5 compression test! Help!
Does anyone know if a regular single hose compression tester will work on an LS1? I wouldn't see why not. If it does what would be a sign of good compression compared to bad compression? Any input would be appreciated.
Thanks!
Thanks!
Melting Slicks
Joined: Jan 2001
Posts: 2,635
Likes: 2
From: Aloha, Oregon
Re: C5 compression test! Help! (dahoof)
a standard compression test kit with all the spark plug hole adapters will work fine. A 10.1:1 compression LS1 motor will yield 175-185 psi. all you need to do is unplug each bank injector wire harnesses at the large plug under the covers to prevent the engine from starting. I also pull the fuel pump relays/fuses to be safe.
Thread Starter
Burning Brakes
Joined: Dec 2001
Posts: 1,190
Likes: 0
From: Jonestown, TEXAS
Re: C5 compression test! Help! (CP)
What does that mean? The tester I have requires that one spark plug at a time is removed. Which fuse controls the fuel pump?
Thanks! :cheers:
Thanks! :cheers:
Le Mans Master
Joined: Aug 2001
Posts: 7,064
Likes: 18
From: Arizona
Re: C5 compression test! Help! (dahoof)
when i did a leak down on my ls1, i just pulled all the wires on the side I was working on and did the test. Becareful not to drain your battery. I killed mine by plug 6. :cuss
Racer
Joined: Oct 2001
Posts: 442
Likes: 1
From: San Clemente CA
Re: C5 compression test! Help! (dahoof)
Hi,
This is what I did for a compression test:
Remove the plastic covers.
Pull the connector for the left & right coil packs (it’s in the center on the top).
Disconnect the injectors by pushing up on the silver wire to release the lock and pulling up at the same time.
You now have no fuel flow or spark and the engine will crank very fast and not run down your battery.
Pull all of the plugs out (this is easier if you disconnect the AIR hoses on the driver side and unbolt the AIR pipe on the passenger side).
Hookup your gage to a plug and while holding the throttle down crank the engine 5/6 times which is enough to get you a stable value. You will hear each cycle easily because only the one cylinder has compression.
My 2002 LS1 stock averaged 150psi with a low of 140. Chevy says something like 10% spread is OK. With a Comp Cams 218/224/114 the compression was 180ish.
Good luck,
Steve
:seeya
This is what I did for a compression test:
Remove the plastic covers.
Pull the connector for the left & right coil packs (it’s in the center on the top).
Disconnect the injectors by pushing up on the silver wire to release the lock and pulling up at the same time.
You now have no fuel flow or spark and the engine will crank very fast and not run down your battery.
Pull all of the plugs out (this is easier if you disconnect the AIR hoses on the driver side and unbolt the AIR pipe on the passenger side).
Hookup your gage to a plug and while holding the throttle down crank the engine 5/6 times which is enough to get you a stable value. You will hear each cycle easily because only the one cylinder has compression.
My 2002 LS1 stock averaged 150psi with a low of 140. Chevy says something like 10% spread is OK. With a Comp Cams 218/224/114 the compression was 180ish.
Good luck,
Steve
:seeya
