I am looking at Buying a LB7 truck from a neighbor. It had new injectors put in last week by the stealer and since has been using coolant. He is tired of it so is selling it. I am thinking cups are leaking, question is does the leak damage any internals if run for a few hundred miles. Had a IH pullin tractor with a leak that made the piston look like a golfball. Also should be able to diagnose which one by pulling the glow plug i would think. thanks for any help

I've heard that coolant leaking into your oil can eat away at the bearings.

yea its called "washing out" the coolant is thinner than oil and thins out the oil and can mess things up bad in any motor...just replaced motor in my friends truck cuz intake was leaking into block and washed out one of the crank bearings...

nah unless he ran it for awhile. Look at how many lb7s have had gallons of diesel in the oil. Yes diesel lubricates but it still breaks down/thins the oil. I bet it is a cup too. Should be an easy fix. How does it run otherwise?

The coolant leak can possibly coke up the tips of the injectors....really fast. I had a coolant leak from a hose the runs right over an injector hp line. That coolant made its way down into the combustion chamber and ruined that injector. So be careful.

Ask how many miles have been run on it with the leak.

no oil in crankcase he had been watching for that. I am sure one of the cups are leaking has 130k service truck so it doesnt work all that hard wouldnt think it would be head gasket. stared usen water as soon as he got it back from stealer. they said bad injector would burn the gasket. Don't know about that one looks sounds and smells like BS.

Bad injector would burn the gasket??? Not sure what that means. If you have a leak from the cup, the motor will burn it no problem. You may get some traces of it if you do an oil analysis.

But given the LB7 injectors and their storied history, it did not take much...I would say less than 1k miles to really foul up my injector tip...to the point I just replaced it.

My guess is that when they replaced the injectors, upon pulling them they may have dislodged a cup and not notice it. Or they pulled some cups and did not do a good job of cleaning the head surface where the cup taper contacts and seals.

Either way the injector lifetime, IMHO is reduced with a truck driven with a leaking cup.

He better take that truck back and have them pull the injectors they installed and seal the cups according to GM specification and using the red Locktite GM specifies! This is where it gets costly for a Duramax owner and they then become a Ford or Dodge owner. The dealer needs to own up to this mistake. Also, a bad injector will take out a piston, not a head gasket!

Its a cup. Coolant shouldnt hurt anything if caught soon enough.
Take it back to the dealer and have them fix their screwup. Call GM and file a service complaint too.