PeachParts Mercedes-Benz Forum - View Single Post

mplafleur · #13 02-19-2002, 10:19 AM

I've heard that .7 bar is the minimum oil pressure you should have while running the engine. While oil viscosity sure can have an effect on your oil pressure, the higher oil weight should result in higher pressure. Being in Florida, I wouldn't expect that straight 40 should be a problem, any time of the year. It's plenty warm enough. Only up north here would I start to question cold starts with heavier wieght oil.

My engine was doing the same as yours. It would go to zero at idle. If you bump the throttle to raise the RPM only by about 200-300, the pressure would rise to about 1 bar. If this is the case, my guesss would be worn main and rod bearings. More I think from the main bearings. You've got too much oil leaking out of the bearings to keep the pressure up.

I replaced my rod and main bearings when my timing chain broke. I did nothing to the pistons, cylinders or the crank. My oil pressure at idle is now just above 1 bar.

Now, it is possible that it is the oil pressure sending unit or the gauge might be faulty. You might want to check these before rebuilding the bottom end of your motor.

Does the pressure seem ok right after you start the car? Does it go to 3 bar within 3 seconds? An indication of the worn bearings is high pressure at cold and zero pressure when the oil is hot.