04 lb7 w/ cyl 4 bal rate 15

2004 lb72500hd

New member
Mar 19, 2020
Truck ran great, got up one morning started it and it was smoking white bad. Running rough and coughing a little thru the exhaust....I think I made the call too early to replace the injectors. I really didnt do any diag on it. So i tore it down. Put new sac00’s, delco c headgaskets, resealed all cups, rebuilt filter head. Everything visually looked ok as far as piston tops, valves, deck surfaces. Put it together and started it. Constant heavy white smoke , rough idle, acts like it doesnt want to clean out. I have only started it twice. So i go and do some checking, resistance is .6 on all 8. Compression is 270-320 across the board cold. Im lost. I just bought the truck, ran perfect for 2 days. It has a holley lift pump edge cts2 and exhaust thats it. Im not sure where to look anymore. All grounds are hooked up clean and tight. About to have it towed to a specialist.. any insight would be much appreciated


Jan 30, 2018
I would post your compression for each cylinder, 270-320 is a big range and on the low side. What is the MAF, rail pressure, and fuel rate at idle?

You sure you didn't leave a rag in the intake? (Might be asking from previous experience)

Burn Down

Sep 14, 2008
Boise Idaho
Your compression is way low on all 8... How did you do the compression test? A healthy LB7 will be in the 390-420 range. The last LB7 I worked on with+15 had a rod bent so bad the piston and the crank were doing some custom machine work on each other...


Why do I keep doing this?
Staff member
Apr 19, 2008
Mid Michigan
Oh, that'll be a good one when the piston is lower than the deck. Ask me how I know. :)

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