W123 Oil Pump
 

Hi there, the oil gauge is showing zero pressure at idle on a 78 280ce/M110.

Anyone know where to find a rebuild?

Dont believe Mercedes still makes them available.

Thank you....

First check the pressure with a manual gauge. M110's use an electronic sending unit for oil and coolant gauges.

Attachment 163473

Second (or first actually), check the lower oil pan. All too commonly on the W123's, the pans have been smashed by impacting a parking block, curb, etc. which forces the sheet metal into the oil pickup tube impeding the lubricant flow.

Hi Mike. Thank you. Oil pan is OK. Guage is direct to dash. Seems that Laso W0133-1604850 is a replacement but no luck finding one so far !!

blackmerc, oil pump failures are uber rare. If they do have a problem it may only be a relief valve stuck open with debris.

Is the engine tapping or knocking, can you see oil on the cam through the fill cap? If it sounds normal something is going on in the gauge.

Good luck and please post your findings.

Thank you for your help on this. The oil pressure is good when the engine is cold/ warming up. Im using synthetic 5-20 oil. When its warm/hot -- that when I see the guage drop to zero at idle. The oil pan/sump is protected by a guard... guage is directly connected, not via a sender....

Consider trying 15w-40 non-synthetic oil for both the thicker viscosity and the higher ZDDP level to protect the flat tappet/sliding surface camshaft.

Good luck!!!

Did you solve your issue? :)

This thread is a few years old, but it is clear to me that the 20 wt oil is his problem. Nearly all old diesel engines are made for some sort of 40 wt oil. Generally 15w40 for regular diesel oil. Today the synthetic multivis oils come in a wide variety of viscosities and some engines are even built for thinner oils like 30wt, but none that I am aware of recommend 20wt oils.

I thought I was in the diesel section. What I said also applies to gassers except that they usually use 30 wt oils and some newer cars are built for 20 wt oils. If you have oil pressure problems at idle when the engine is at operating temperature, try a higher viscosity oil.