Low oil pressure in 1993 CK 2500 6.5

[dmmotes]

I have low oil pressure readings with oem gauge as well as three other manual gauges hooked up at oem location on block where sending unit mounts and at the turbo, all gauges reading 5-6lbs at idle and 20-25lbs max 3000 rpm engine at thermostat temperature. This engine has 111,000 mi and has been meticulously maintained seems to have good power with very little oil use.This problem seem to come on slowly and has existed for a some time.I don't know where I should go next to find the cause of this problem.

[rjschoolcraft]

Welcome to the forum!

This topic was moved to the 6.5 forum for more exposure.

One of the usual suspects for low oil pressure is increased clearance in your rod and/or main bearings. If so, that's bad news.

[rjschoolcraft]

Bump.

Just to bring this back to the top for more attention.

[ 02-16-2005, 03:48 AM: Message edited by: ronniejoe ]

[Barry Nave]

Bump :confused: Lost me on that one ;)

[john8662]

Next step, pull the oil pan.

I had to do this with my 1995 after suddenly seeing lower oil pressure than normal on my rig, it drove me crazy as I worried about it being too low. The readings that you are getting fall under the really low category, but show barely in spec under the books. Which truck do you have, four wheel drive or not? On the 4wd models it's not too bad to remove the pan, but you'll first have to lower the front axle assembly to get enough clearance to remove the pan, but not completly remove the axle.

If you need some hints on the pan removal, post back.

Once you get the pan off you have some options, number one, check for cracks on the main webs of the engine, this won't lead to low oil pressure, but will lead to finding another engine. If you're clear there, then you can proceed to remove the oil pump and then the rear main bearing cap, I'd have a look at the bearing condition. If good, carefully put it all back together, and add some assembly lube to the bearing and crank before re-assembly. If these items are good, proceed to the next step

Next, go to the dealer and get a complete oil pump assembly for a 98 model 6.5TD engine in a 3/4 ton truck, etc. This oil pump is a bigger oil pump than the original oil pump that came in a 93 it is higher volume (not pressure) pump. Install this oil pump, and you should have good oil pressure again. Or installing a new oil pump of the same vintage should also fix the problem if it is an oil pump failure.

The failure that I experienced with my 6.5 was that the oil pump pressure bypass had started blowing off oil pressure prematurely. The bypass had failed, so you replace the oil pump.

[Scooby]

I would also pull a couple rod caps at the end opposite the oil pump, to ensure they had not been damaged from lack of oil.