New LB7 Owner


New member
Apr 28, 2021
Just bought my first Duramax, had a 7.3 ford back in the day...

Have 2 problems

oil dripping from skid plate
AC does not work ie compressor will not turn on.
Suggested i start to find the oil leak first.

Thoughts on where to look first?

Also 190,000 miles, runs and idles great, does not smoke, no blow by from the oil fill, clean antifreeze, oil was changed before i bought it so clean, only driven it about 50 miles oil still clean does not appear to have diesel present.
Last edited:


Heavy & Slow
Sep 3, 2009
Boise, ID, USA
The LB7 vents the PCV down the right front of the motor, and that can accumulate and run down onto the skid plate. Especially if the oil separator/drain is not working. You're probably just going to have to pull the skid plate and clean all the oil off the motor, then see where it is coming from.

The A/C might just be low on charge. If so, you might want to replace all the stock gaskets with the new green Viton o-rings, which last a lot longer. Of course look for obvious leaks/damage first. These are pretty reliable A/C systems, so it is a bit unusual to have them leak down for no reason.

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