thanks for the info guys, especially oldbull.
we did a comp test on the engine with it cold and all three cylinders were right at 250. so we know that it is not a piston, ring, cylinder wall problem with the far back cyl.
All the varrying differnt compression readings that youve been getting tell you right off that it's just a sticking ring problem and not a mechanical problem. When teh rings can't flex freely in their groves, strange things happen. Once you get it all cleaned out it should take care of the problem
when I first got my truck, the back 2 were reading around 135 and after the auto Rx they were all up over 400 psi, and it was probably one of the milder cases I've used the stuff on.


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But it has to be done, those critters were built to cruise with the big Benzes on the Autobahn . too much time puttering around in traffic and they carbon up something fierce and start running like crap. 20 minutes of that high rpm screaming , and it runs like a dream again