While I had my glow plugs out to crank the motor for the HPOP work I have done I checked the compression on all the cylinders. 6 of the cylinders were 275-280, got 250 and 110 on the others. I put oil in both the low cylinders and the 250 went to 260 and 110 went to 150. I pressurized the low cylinder and with the valves closed it was leaking out the exhaust manifold also had a small amount of coolant come out the water pump. Removed the cylinder head and didn't see anything unusual with the cylinder that was reading low in fact the if was the best looking cylinder of the four with nice looking crosshatch on the cylinder wall. The other three cylinders has some slight brown haze on them which I assume is rust. This motor probably hasn't run in 18 months and the truck was a non-runner when I purchased as a theft recovery, no history on the truck.
Taking the one head to a shop for them to check it out.
What's the opinions out there with the low compression? Be ok once it runs and rings get coated with oil?
The motor is out of the truck so maybe I should tear it down completely hone and put new rings in it.

 

Had one bent valve and worn guide. Hone cylinders, new rings, bearings, lifters, push rods, head studs, 2 new batteries. Performed compression check for the record and all cylinders running 275-300. Could be my gauge is off. Motor on the frame, cab back on frame, turn key cranked for 30 seconds and started. Finally after a year or so.

 

Congrats! That was a lot of work.