Generation III Internal Engine 1997-2006 LS1 | LS6
Sponsored by:
Sponsored by:

Troubleshooting Low Compression/High Leak Down

Thread Tools
 
Search this Thread
 
Old 03-30-2017, 05:30 PM
  #1  
Staging Lane
Thread Starter
 
tommypenguin's Avatar
 
Join Date: Jul 2015
Posts: 81
Likes: 0
Received 1 Like on 1 Post
Default Troubleshooting Low Compression/High Leak Down

Hey guys, I have an 01 Supercharged Corvette. Long story short, I had a failed oil pump and cracked block 5k ago, got a new block, machined and swapped my rotating assembly over to it. Wish I could have gone forged but the budget didn't permit at that time.

Was driving last weekend and noticed some smoke in my rear view at WOT but not at any other time while driving. Got home, pulled plugs found oil on cylinder #7. Did a compression test, that cylinder is showing barely 15 versus 180 on the rest, except cylinder 3 which showed 155. Then did a cylinder leakdown test after removing the rockers on that cylinder so the valves stay closed and that cylinder when regulated to 100psi was only retaining 20psi. Valve springs look good, valves are there at least but could be bent in a best case scenario.

I do not have any CEL or misfires, car felt fast, no noticeable driveability issues. I have HPTuners and can take a log if it would be helpful. Was going to pull the oil, cut filter open and insepect then pull the head. Should I do anything else before taking these actions? Thanks.
Old 03-30-2017, 05:51 PM
  #2  
TECH Addict
 
RockinWs6's Avatar
 
Join Date: Mar 2013
Posts: 2,628
Likes: 0
Received 27 Likes on 21 Posts
Default

You could scope the cylinder and look for damage but I would say its safe to pull the engine and replace number 7 piston. I'm sure from your description it has failed in some form(broken melted etc.
Old 03-30-2017, 05:53 PM
  #3  
On The Tree
iTrader: (1)
 
andrewss's Avatar
 
Join Date: Dec 2010
Location: gta
Posts: 117
Received 0 Likes on 0 Posts

Default

Find out where the problem is during the leak down test . With that much leakage , should be easy to find.



Quick Reply: Troubleshooting Low Compression/High Leak Down



All times are GMT -5. The time now is 07:54 PM.