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Caterpillar D8H oil pressure problem

C

cinahcem

Active Member
Joined
Dec 9, 2015
Messages
26
Location
Manitoba
Hello,

I'm looking for the old boys on this one, I have a 1967 D8H s/n 15848 dozer. My oil pressure is on the low side that when I idle the machine down the oil pressure drops so low that it won't let the fuel rack open up. I checked the oil pump, main bearings and rod bearings they all had wear so replaced everything. It still never changed it. Any suggestions to where I should go from here would be great. I also checked the oil filter housing and cleaned the cooler bypass valves and filter bypass valve.

Thanks
 
T

tctractors

Senior Member
Joined
Oct 9, 2007
Messages
2,426
Location
Worc U.K.
There is a possibility that a steel oil pipe has cracked through or often the union just becomes undone, on the oil pressure detail the high idle is only 30psi the oil pump has an over pressure control set at about 90 psi for cold oil protection, but the oil pump has a flow control valve that sorts things, the steel lines are down in the depths the common 1 to be loose is at the back head around the lifters, but the pipe in the crank case might be your culprit, you can always pump oil in through the turbo oil line with the engine stopped using a barrel pump and look for leaks?
tctractors
 
C

cinahcem

Active Member
Joined
Dec 9, 2015
Messages
26
Location
Manitoba
Hello there, I finally got back to this D8H and the information you gave was greatly appreciated. I pumped oil in through the turbo line and found out that the elbow on the main tube where it comes from the filter housing had a hole in it about 1/2 inch in diameter, and it looked like something was wearing into it which led to more problems. The bolts that hold down the cam follower guides were broke and they were moving in there which caused the follower to move sideways a little bit and wear on the elbow so it looks like I caught it in time. I checked the main bearings and the turbo and there was no harm done. I was also checking the oil pressure on two different machines around the same serial number and the oil pressure was 40 psi on low idle and 60 psi on high idle on both machines and they both were running chevron 15w-40 oil in them.
 
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