Compression for my truck : 1-130,2-140,3-140,4-150. It has 251XXX thousand miles on it and counting. I bought the truck with 162XXX and had the famous manifold crack shortly after. at about 180XXX. Put a new manifold on and sometime later it cracked again, at about 213XXX I beleive. This time I had a blown head gasket and cracked head which I have a hunch was caused by the exhaust manifold. Had the whole top end rebuilt, radiator, timing chain, seals, new exhaust manifold, etc. Truck was running great until I heard the tick tick tick. at 240XXX Another exhaust manifold plus blown muffler. I just now found the mini header and had that installed this last Tuesday and had them do a compression check. The truck engine runs great. Idles great, no check engine lights, but the compression is low. The mechanic said there is some noise from the valve train. Does anyone have any insight into what problems may be causing the low compression? I spent a lot of time and money into this truck and I am getting discouraged and don't want to spend much more money.

 

Rings are getting worn most likely.
Mine has about the same compression numbers. New would be about 170 psi.
Runs fine. Uses some oil. No big deal to me. Will rebuild it someday when it really needs it or I have time to do it.