Oil pressure

[1985GN]

Hi, I've got a 95 Blazer, 4.3L, just bought it, 48,000 miles, clean, good shape. However, after it warms up, the oil pressure drops. At idle it dips just into the red, and the check guages light comes on. While driving, it comes back up, but only to about 30 on the guage (guage reads from 0 to 80). Checked the oil and it is full, maybe even a little too full. The oil is also very clean. I'm no expert, but it sounds like a bad oil pump to me. If so, how hard is it to do an oil pump on one of these? Thanks for any help.

[cobra1]

could be oil pressure sensor, and if im thinking right it could also be a worn main bearing.

what is the pressure reading on a cold start? and what weight oil is in it now?

[1985GN]

It's about 50 at start up idiling. I'm about to drive it to work so I'll see if it gets any better or worse. Pretty sure it will drop when it warms up. As far as I know it's got 5w30 in it.

[1985GN]

Well, it's just as I thought. 5mile trip, it got progressively worse, and by the end it was doing the same thing. In the red at idle and about 30 while accellerating.

[1985GN]

Stopped at an auto parts store and got a repair manual. Not a simple job, replacing the oil pump. I'm just glad it's not a 2wd (remove engine!). Pump was only $45 hopefully thats all it is. Looks like I'll be busy this weekend. If anyone has any suggestions of things to look for when I've got the pan off, I sure would appreciate it.

[Friction57]

Hey,

I got a 93 Blazer that had a similar problem. In my case, it was the oil pump that went bad. While you've got the pan off and your pulling out the oil pump, make sure to clean or replace the pickup screen. That could save a lot of headaches in the future. Good luck.

[1985GN]

Hey friction, did your oil pump go bad at 48,000 miles? I had a guy (mechanic) tell me today that it's not the pump. He said "either it works or it doesn't" meaning that if it works when the oil is cold then the pump is good. I'm skeptical, though, to me it makes sense that the pressure would drop when the oil gets hot if the pump is worn/bad. He also said that it could be one of 2 things, either debri in the oil pan that is blocking the pick-up screen, and that I should drain the oil, and use some brake parts cleaner and spray it into the oil pan from the drain plug hole to clean out the bottom of the pan or, the bearings are all shot and causing a pressure drop. So, I cleaned the bottom of the pan out per his advise. Even used 2 quarts of oil and poured it in to make sure I got all of the brake cleaner out of the bottom of the pan. The oil was clean, and no debri was found. I restarted the engine and the same thing, 10psi at idle and no more than 30psi driving. I got a mechanical guage and hooked it up, so I know that the sending unit and dash guage are not the culprit. The only thing left to do is drop the pan and replace the pump and screen. If I'm missing something, please help. I really don't want to replace the engine.