Last winter I bought a 93 LeSabre from my uncle for $200 for something to get me through the Wisconsin winter. About two weeks ago, the engine had about 3200miles from the last oil change, I was driving home and the oil pressure just dropped while I was driving. I would give it some gas and the pressure would go back up. It got to the point where the needle was in the red and the light was coming on blinking. I pulled into my drive way slowly and the car died. I just left it where it was because I thought I had seized up the engine. Well I thought all the oil just leaked out. The next day bought a quart of oil dumped it in and it started. I took it to the oil change place and thought all would be good for another 3k miles until all the oil leaked out again. I was driving the car around the Sunday after and the pressure started dropping again! I checked the dipstick the next time I stopped and the oil is all the way full where it should be. I've driven the car maybe once or twice since then and every time I start the car and the oil pressure is where it should be but after driving around it just starts to drop and every time I hit the brakes it seems like it drops more.

Does anyone know what would cause that? I thought it was really weird because it starts ok but then after driving it goes down. I want to start ripping my bike apart tonight and doing the SS lines but I'm afraid to try to drive it to work and get stuck with no oil pressure half way there.

Help!

Mike

 

oh my gawd dude! noooo!!! lol i hope your bike survives [sm=badidea.gif][sm=icon_beat.gif]

 

sounds to me like it could be a oil sending unit. other than being low on oil, it is about the only reason (that i know of) that would cause your oil pressure to fall. just my .02

 

Sounds like your oil pump is taking a dump. Often times when oil pumps go out it will cause the oil pressure to drop only after it gets hot because the viscosity of the oil thins out when it heats up, making it harder the the oil pump to 'pump' it. When it's cold and the oil is thicker it's much easier, so even a weak oil pump will be able to pump it until it gets hot. Of course worn rod and/or crank bearings will also cause low oil pressure, but an oil pump is usually my first suspect, as well as the easiest to change.

We see this problem alot on the diesels, 05-06 6.0's in particular. They use a high pressure oil system (which operates from 600-2000 psi oil pressure) to run the injectors. The PCM needs to see at least 500 psi of ICP pressure before it will even fire the injectors, so anything below that and the truck won't start. They use dinky little o-rings and quick connect fittings to hold all this pressure, which blow out allllll the time and cause leaks. With a small leak, the truck will start fine cold, then you go drive it around for a lil bit and get it hot, shut it off and it will not restart for anything, for the exact reason I mentioned above. Once you let it sit and cool down for a lil while, it'll start back up fine. Oil viscosity makes a biiiig difference in oil pressure!

 

+1 or you have something in the oil pickup or oil pump is going.

After you confirm the sensor is OK...

My 70 vette did the same thing, it was plastic timing chain quieting thingys that came off the chain were scattered in the pan, some were packed into the pickup.

also the pump is run off of the cam, the 'pushrod', cam lobe, oroil pump arm may be worn and not giving you the stroke to pump that as well as it needs to be.

Drop the pan, look for crap, remove/replace/inspect rod and pump.

 

Awesome thanks guys! I'll take a look into replacing the oil pump and see how hard it is to do, maybe I'll do it on the vacation week I took in 2 weeks when I was originally planning on going to deals gap. It's always something right before I want to go there.

Thanks again!!

MIke

 

im a mechanic by trade and with these guys, my money is on the oil pump.

you said the pressure drops after driving it, but is ok for the 1st few mins, or even 1st couple trips. the oil sender is electric, but highly reliable. they don't usually have intermittent internal failures. (it works or it doesn't..) so but the oil pump is a mechanical device that has tolerances, and will expand and retract with heat. so once your oil thins out, its not hard to believe pressure will be lost. reguardless of the oil.. chances are with new oil, the viscosity, and condition isn't the problem, its the mechanical part failure.

not sure if your in a cold climate environment, but you could try a thicker oil. 40-50 wt. oil, but.. if you live in alaska, those cold start morning will sound like a dead battery, and will put alot of stress on the starter.

just curious, what wt. oil are you using now? what kind of climate? kinda odd you stay up on oil changes, fresh oil, but loose oil pressure after a good drive.. somethings wrong.. that oil pump needs to be freshened up.