Factory Remanufactuer 12.7 built by Detroit. in a semi with a 100 thousand on it. They have been playing around with different turbos and ECM tunes during the miles.


Cylinders would leak down a 100 lbs in 20 seconds on a leakdown test.

Said to be badintake valves.

It sounds like the only way to truly find out what's going on is to pull the valve cover inspect, and go from there. If nothing is found there you might have to pull the head. Double check to make sure it's on the correct stroke when performing the leak down test as well. I don't know much about the smaller truck motors but the big boy Detroits can be confusing to figuring out the position each cyclinder is on going by the balancer (16 cyclinder motors)

I belong to the Mercedes discussion group -- and I have had 3 Benz diesels. What you state is a very common issue with diesel engines not being run for longer periods and hard -- Run it like it was stole-- the more you run it the better.

3pointstar

Does this motor have variable valve timing?

Pre 03 no EGR or DPF. No variable timing. Head is already off.Head was reconditioned 100 thousand ago by Detroit.

Check the valve seats for good sealing surfaces. Before that head goes back together it would be a good idea to lap each of the valves in by hand and check the patterns on the sealing surfaces to make sure they will properly seal.