I am having coolant pushing out of the tank after it idles for a bit and when at steady speeds for a half hour. I know it has either a bad head gasket or leaky injector cups. I have no coolant in the oil. It has 140k on it and at 75k it had all injectors done before I bought it. I do not have much experience on diesels. I was wondering if there is a way to tell which one is the issue. If I don't have to pull the heads, I would rather not. Any advice would be greatly appreciated!

 

have the injectors ever been replaced? are you pushing high HP or boost levels.

 

Yes the injectors were replaced at 75000 under gm special policy. The truck now has 14000 on it now. I bought it with 12000. It is 100% bone stock. I've been doing research on here and saw a few other stories like mine. The boost is in the normal range. I only use this truck to pull a 8000lb trailer and I don't beat on it. I find it odd that the radiator hoses do not get hard. It started off last year that I noticed the coolant level would be periodicly low. Then I noticed the water pump and the three inch hose near the oil cap leaking. I changed those and that is when the coolant started spewing out of the overflow jug. When I let it sit overnight, The next day the jug is empty and I pop the cap and coolant spews out. It will then not take anymore coolant in, even after i vacuum the entire system I can not get the air out.

 

opps, should have saw this on your first post

to release the air from the system (bleed the air) there is a bolt on the top of the thermostat housing. try refilling it with the bolt loosened. when water starts to come out of the bolt hole tighten it down and continue filling till full.

if it still overflows then i would think it would be a HG

 

Thanks for the input 2004LB7. I have already done the factory air bleed procedure. How would you know if it is a cup or a gasket? I believe it is a gasket myself. I Think I am going to just go ahead and replace head gaskets and reseal all the injector cups to be safe. I don't want to tear it down twice.

 

i think that that is a difficult one to tell. from everything that i have read it is a guessing game. since your injectors warn't replaced recently then it seems that it is more likely a gasket.

its not a bad idea to do the cups at the same time when you get it apart. the green locktite is supposed to be the best for sealing them.

 

Thanks for the advice 2004 LB7! I'm going to tear her down this Sunday.

 

sounds like gaskets to me, but the LB7 is a finicky beast if it were an LLY or newer i would definately say gaskets to me, same symptoms mine had

 

Thanks again for the advice and I was also wondering what type of mild tuner is the best for better fuel mileage and just a touch more power with out changing other parts or damaging stuff? The truck has plenty of power stock but mainly want better fuel mileage.

 

just about every tuner has an economy tune or one that works well for mpg. really any mild boost in HP should result in in some MPG gain

personally i like EFI Live. i have ran the Diablo Sport Predator and the 60HP tune seemed to work well for MPGs. got me 1 to 1.5 more MPGs

right now with my own EFI Live tuning i was able to get twice as much HP as the Diablo and still get the 1 to 1.5 MPG gain. i made one tune that net-ed me about 2 mpg but was a little high on the timing