LS1 sat for a year wierd compression when checked
Thread Starter
Teching In
Joined: Aug 2012
Posts: 6
Likes: 0
LS1 sat for a year wierd compression when checked Been lurking here for a while gathering info for my project. Love the site.
I recently picked up an 2001 ls1 and have been getting it ready to drop in. When I purchased the motor last week I was told it came out of a running car that was wrecked in the rear. I did a vin check and can see that it was salvaged almost one year ago next month. So it sat for a while drained of oil.
I did a compression check this morning after adding new oil and filter, and pouring some inside of the valve covers. With it still on the engine stand I also turned it over a few times by hand. My first compression check showed:
1) 120. 2) 180
3) 210. 4) 210
5) 210. 6) 60
7) 210. 8) 60
So I added a little oil to the cylinders and turned it over a few times and then let it sit for about 4 hours. When I rechecked it I got:
1) 150 2) 175
3) 195 4) 180
5) 190 6) 180
7) 180 8) 170
I checked the compression per the service manual, 4 cranks per cylinder. I recheked it 2 hours later with the same results as above.
My motor is still covered by the yards warranty and I wont be getting it running for a few more months, but I am at the stage where I am getting parts and having the ECU and wiring harness done. So Im not sure if the low compression was a result of sitting and being dry or I should take this one back and get another one?
I am very new to these motors so please excuse my lack of knowledge. I appreciate any insight you can provide.
I recently picked up an 2001 ls1 and have been getting it ready to drop in. When I purchased the motor last week I was told it came out of a running car that was wrecked in the rear. I did a vin check and can see that it was salvaged almost one year ago next month. So it sat for a while drained of oil.
I did a compression check this morning after adding new oil and filter, and pouring some inside of the valve covers. With it still on the engine stand I also turned it over a few times by hand. My first compression check showed:
1) 120. 2) 180
3) 210. 4) 210
5) 210. 6) 60
7) 210. 8) 60
So I added a little oil to the cylinders and turned it over a few times and then let it sit for about 4 hours. When I rechecked it I got:
1) 150 2) 175
3) 195 4) 180
5) 190 6) 180
7) 180 8) 170
I checked the compression per the service manual, 4 cranks per cylinder. I recheked it 2 hours later with the same results as above.
My motor is still covered by the yards warranty and I wont be getting it running for a few more months, but I am at the stage where I am getting parts and having the ECU and wiring harness done. So Im not sure if the low compression was a result of sitting and being dry or I should take this one back and get another one?
I am very new to these motors so please excuse my lack of knowledge. I appreciate any insight you can provide.
Last edited by Littered; Aug 4, 2012 at 03:04 PM. Reason: Can't spell
Thread Starter
Teching In
Joined: Aug 2012
Posts: 6
Likes: 0
Thank you for the input
I have checked a few more times since then and I'm getting a constant compression variation of 12% across all cylinders. Also I am only getting a difference of 6% at most between a dry wet compression check. Keep in mind this is on a cold motor.
I have checked a few more times since then and I'm getting a constant compression variation of 12% across all cylinders. Also I am only getting a difference of 6% at most between a dry wet compression check. Keep in mind this is on a cold motor.
The engine should also be a operating temp for a more accurate compression test since the pistons are cam ground meaning the clearances aren't where they should be cold.
Trending Topics
Thread Starter
Teching In
Joined: Aug 2012
Posts: 6
Likes: 0
I had it on a stand with a starter and battery hooked up. I ended up trading for a 20,000 fewer miles motor. I dont think the pressure should be 60psi even when cold. Especially when all other cylinders were hitting 180s.
Im not anywhere near a point to have it dropped in and didnt want to worry about it. I appreciate the help!
Im not anywhere near a point to have it dropped in and didnt want to worry about it. I appreciate the help!
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
