Visit The Dirt Forum for More Information

Author Topic:   oil pressure
jeff woodson
Dirt Full Roller

Total posts: 42
posted December 04, 2005 06:15 PM  
i just bought a 97 GMC 6.5 turbo. The owner didnt have maintenance records. So i changed oil, with the recommended Rotella 15w40, and the AC filter that is required.Now for my problem, when the oil is cold it will have 40psi at speed, as soon as the oil heats up its only 20psi at speed and 5psi at idle.The engine has 97000 miles. What gives? can anyone help? It was just fine (oil pressure) before i changed oil..... thanks

TEAMPCR
Dirt Freak

Total posts: 246
posted December 06, 2005 02:55 PM  
Verify the reading with a mechanical guage first, to make sure the electric sending unit isn't all gunked up. Also, make sure the bypass isn't stuck and the correct filter is installed. I'm not sure if that take the filter with the built in check valve or not. If not, the check valve could be restricting oil flow. (?) If the pressures are still low, it is possible you have been bamboozled by either sludgy oil from not being changed, or 90W in the crankcase, either of which will make the pressure read high. Most likely, with 97K miles, and no maintainence records available, the thing needs rod and main bearings and/or an oil pump.

jeff woodson
Dirt Full Roller

Total posts: 42
posted December 06, 2005 04:20 PM  
thanks for your reply. When i changed the oil i looked at and it was not at all thicker than normal.Is the check valve located in the block above the oil filter? The AC filter that the manual calls for DOES NOT have the check valve. Rod and Main Bearings? God i hope you are wrong. I can deal with replacing the pump, or else fill her up with Lucas and keep on trucking........

TEAMPCR
Dirt Freak

Total posts: 246
posted December 12, 2005 06:12 AM  
If you pull the pan to replace the pump, it really wouldn't be that much more to replace the bearings. (a couple of hours and the price of the bearings) The check valve is in the filter, I don't know how much it would affect flow, exactly, but it will restrict it to some degree. If the filter you installed is an AC/Delco PF-1218, it has the check valve.

diesel rat
Dirt Newbie

Total posts: 2
posted December 18, 2005 08:04 AM  
the check valve you see in the filter is a bypass valve to supply the engine with dirty oil if and when the filter gets plugged. i dont know 6.5's but i would imagine the oil pressure regulator is on an oil galley or the pump body. if you already have the pan off drop the pump and then a rod and a main cap furthest from the pump to assess the damage. 5psi is definetly not enough, metal to metal contact is occuring.

Back to the Archives