I have a ''''93 Saturn SC1 with around 180K miles. During the last week or so, the oil pressure warning light came on once or twice as I parked after a drive. I checked oil levels and they were fine, so I hoped it was just a glitch. Yesterday, I took a fairly long drive and after about an hour, the warning light came on again.

At first, it was only coming on when I braked at low speeds or while stopped at lights. I started to head for home, and after another 20 miles or so, the oil pressure warning light came on even when I wasn''''t braking and the engine temperature gauge indicated the temperature was rising. I stopped to let the engine cool down, so the gauge only rose a little bit above normal, but it was definitely higher than I''''ve ever seen it before.

I was able to get home, and this morning I took the car to the mechanic. No warning lights appeared and the engine temp was fine for most of the 20 mile drive, but right at the end, as I was stopped at a red light, the oil warning light came on and the temperature gauge went higher again.

Despite having to drive on the Interstate going home last night and going to the mechanic this morning, the warning lights didn''''t show and the temperature was fine while on the highway. It''''s only when I''''m on slower streets with traffic lights that the problem occurs. (Of course, this might be a coincidence.)

The mechanic said I should have the oil pressure switch changed. I''''m confused, though, as I don''''t understand how a problem with that part would cause the engine temperature to rise.

Any advice would be much appreciated!

P.S. Two things I forgot to mention: Oil level is fine, and I didn''t hear any unusual engine noise.

Edited by: DavidV

 

DavidV ...


I have to agree with you, a defective oil pressure sending unit will not cause your engine to run hot. Here are a couple of scenarios that might cause a similar condition .....


First, is the possibility of a weak/worn oil pump. As the engine heats up, the oil flows easier allowing less pressure at the pump outlet.


Second possibility is plugged oil return passages from the head and valve train area. As the engine runs, oil becomes trapped in the head chamber, starving the oil pump and creating a low pressure condition. When you shut the engine off, the oil will s-l-o-w-l-y drain back into the pan, so when you check the level, it seems OK


I am not saying that either of these conditions exist in your car, but a bad oil pressure sensor will not cause the engine to run hot