low oil pressure

[Jay]

I just noticed that my 95 E300D has no oil pressure at idel after the engine is gets hot. It seems like the problem came on suddenly. Bad gauge???( maybe just wishful thinking) It has good pressure when the rpm's are up. Any thoughts??? Jay

No pressure as in 0 total or as in very low like 0.5bar?

[Jay]

It goes down to zero at idel when hot. Jay

[P.E.Haiges]

Jay,

I would check the viscosity of the oil first. Try a drip test with oil from your engine and some new oil. Maybe some fuel (although I don't know how) got into the oil and reduced the viscosity.

I don't know how the oil pump or bearings could change to sudddenly cause low oil pressure. And its not the pressure release valve or the oil pressure wouldn't be good at high engine RPM. Not gage either or it wouldn't read normal pressure at high RPM.

P E H

[Jay]

P E H The first thing I did was an oil change and it hasn't helped. Thanks, Jay

[thorsen]

Remove the oil pressure sender and thread in a mechanical gauge. Start the engine and see where the oil pressure is. This will eliminate the gauge or sending unit as the problem.

[ConnClark]

If this is just 0 at idle it I doubt if its the sender unit. This is something that should be dealt with right away as it could be a sign of really nasty things to come.

[romansek]

Jay,

Did you find solution to your oil problem, and what you did? I have the same problem on my 95 E300D.

Thanks,

[Jay]

I fixed the problem by replacing the oil pressure sending unit. It was an easy fix, but disconnect the battery or you can cause a short. Let me know how you make out. Jay

[pawoSD]

Originally Posted by ConnClark

If this is just 0 at idle it I doubt if its the sender unit. This is something that should be dealt with right away as it could be a sign of really nasty things to come.

My car (617 300SD) has been showing 0-.2 bar at hot idle for over a year...and 20,000 miles. Pegs to 3 right away when rev'd. Running strong as ever. I ordered a new sender for $36...I will be installing it when I do my next oil change. I assume it will solve the problem....as the gauge jitters around when I slow down too....


The senders do go bad, and do weird things like show 0 at idle.

[romansek]

Jay thanks for quick response. I will try to test the sender since my 90 300D has the same part, but its very hard for me to believe that that’s the problem. As for the first step, I changed the oil from 15W-40 to Delo 400 straight weight SAE 40 and this did not help. When the oil pressure would fall to “0” with 15W-40 oil I would hear some valve noise and this made me believe that there was a lack of oil pressure.

[Jay]

romansek, is the problem fixed?