I posted this on the Red Power site and thought I'd try over here as well. A couple folks responded with some good ideas. The end result being; I
think I will be removing the oil pan next week. Nonetheless,if any one here has a suggestion I'm all ears.
I replaced the head gasket on 'Ruthless', my TD9-91 with the 350 engine, and all was well for a couple hours when I lost 20 psi oil pressure. Normally
the oil pressure was nearly 60 psi at cold start low idle (1/4 throttle) and would drop to 40 to 42 psi at high idle hot. Which was good. Now it's 22
psi cold start low idle and stays at that pressure high idle hot, dropping to approx. 5 psi low idle hot. The engine has approx. 550 hours after a
rebuild, so I don't suspect a bad main or rod bearing.
The oil gauge is a Stewart Warner, but I checked the pressure with two other gauges and they all agree with each other, so the gauge is not at fault.
I removed the oil filter assembly to check and clean both the bypass and pressure relief valves and they look OK. The springs look OK too, but I
added a 1/16th thick washer to the relief valve spring in case it was a bit weak. It didn't help. I then checked to ensure the expansion plugs were
secure on the ends of the rocker arm tube. They're OK.
Now here is the only fly-in-the-ointment. While installing the rocker arm assembly after replacing the head gasket, a 3/8 lock washer dropped down
past a push rod. I tried for quite some time to find it with a magnet, but no luck so I removed the inspection covers that expose the cam followers.
Still couldn't find it, so it must have found it's way into the crank case. I wasn't concerned because it can't get sucked into the pump through the
screen, but I thought there might be a possibility the washer might get caught up in the counter-balancer drive gears so I rotated the engine over
both directions by hand several times, and all was well. Beyond that, I couldn't think of any way the washer could be an issue unless I rolled the
whole rig on its roof while it was running, so I finished putting it together and went to work.
I'd appreciate you guys pulling your think'n caps down good and tight and let me know what you think might be causing this pressure drop.
I did the copy and paste thing so the format is a bit weird.
think I will be removing the oil pan next week. Nonetheless,if any one here has a suggestion I'm all ears.
I replaced the head gasket on 'Ruthless', my TD9-91 with the 350 engine, and all was well for a couple hours when I lost 20 psi oil pressure. Normally
the oil pressure was nearly 60 psi at cold start low idle (1/4 throttle) and would drop to 40 to 42 psi at high idle hot. Which was good. Now it's 22
psi cold start low idle and stays at that pressure high idle hot, dropping to approx. 5 psi low idle hot. The engine has approx. 550 hours after a
rebuild, so I don't suspect a bad main or rod bearing.
The oil gauge is a Stewart Warner, but I checked the pressure with two other gauges and they all agree with each other, so the gauge is not at fault.
I removed the oil filter assembly to check and clean both the bypass and pressure relief valves and they look OK. The springs look OK too, but I
added a 1/16th thick washer to the relief valve spring in case it was a bit weak. It didn't help. I then checked to ensure the expansion plugs were
secure on the ends of the rocker arm tube. They're OK.
Now here is the only fly-in-the-ointment. While installing the rocker arm assembly after replacing the head gasket, a 3/8 lock washer dropped down
past a push rod. I tried for quite some time to find it with a magnet, but no luck so I removed the inspection covers that expose the cam followers.
Still couldn't find it, so it must have found it's way into the crank case. I wasn't concerned because it can't get sucked into the pump through the
screen, but I thought there might be a possibility the washer might get caught up in the counter-balancer drive gears so I rotated the engine over
both directions by hand several times, and all was well. Beyond that, I couldn't think of any way the washer could be an issue unless I rolled the
whole rig on its roof while it was running, so I finished putting it together and went to work.
I'd appreciate you guys pulling your think'n caps down good and tight and let me know what you think might be causing this pressure drop.
I did the copy and paste thing so the format is a bit weird.
