wrwtexan
Senior Member
- Joined
- Feb 5, 2011
- Messages
- 558
- Location
- Cooper, Texas
- Occupation
- Indy Farm Wrench, heavy land clearing, rancher
I have been tasked with diagnosing and fixing an 801 Ford with a 172 diesel that has just been rebuilt by another local mechanic. It has new sleeves and pistons, reworked head, rebuilt injection pump and tested injectors. Problem is it won't build the 365-400 psi called for. Cylinder 1= 260, 2= 300, 3=300, 4=270. Tonight I verified timing and then pulled #1 piston. The sleeve looks good with new crosshatches, rings aren't damaged and piston is correct. Camshaft is original. The oil was thin and likely was diluted with diesel but not much thinner than the break in oil I use for overhauls. I've never had a compression issue on a back to standard rebuild but could the rings be leaking by enough from not being seated to loose that much pressure? Unless I can find something definite, I will reassemble and load it to its rated power on my dyno and see if it improves. Maybe dope it with a little Bon Ami. What I don't understand is the inconsistency in the compression test readings from front to back.