After reading many post here on this forum i decided my problem with my 1992 500SEl,w140 series was a bad oil tube cap. Today i removed the right side valve cover and checked them,but found no missing caps.I could not see caps visually so i tried to stick a paper clip tip into them and all seemed solid. The part number was 8 118187 0087 . Are these the dreaded plastic tubes that are common to fail or are they the metal ones? They look metal but a magnet would not cling to them.Do these tubes fail in other ways such as warping? Is it a waste of my time to take apart the left side? My problem is i have good oil pressure when engine is started but as engine warms up,the oil pressure gradually decreases and after a few miles it will get dagerously low pressure.Oil pressure gets better as engine sits and cools off.What other problem do i need to look into? My car has 120,000 miles and has always been cared for. Please help. I need this car back on the road.Thanks

Went ahead and removed left side valve cover and checked all oil tubes,no caps missing,all looks well. I really need some help and direction on where to go from here. I love my W140 and am trying to keep it in good shape.I am afraid this low oil pressure will ruin my engine.Please respond.

What are you calling "dangerously low" oil pressure? My 116 drops down to a little less than .5 bar at idle, and the manual says .3 bar is OK so long as it rises when the RPM's come up. Can you see the tubes "peeing" on the cam lobe viewed through the filler cap hole at hot idle? If you can, you're probably OK.

The tubes are metal - like a copper alloy.

I for one don't think the cam oiler assemblies have much to do with oil pressure. But while you've got the covers off, why not replace the caps and all the little plastic holders on the cam towers?

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Oil pressure goes down to about .5 of a bar. This is way lower than i remember it being.What would be the symptoms of a bad oil pump?By the way,thanks for the reply.Greatly appreciated.

I guess a sudden drop in oil pressure our engine noise would be a sign of a pump going bad. But the pumps are pretty simple and it's hard to see how something sudden would happen to them that would suddenly reduce oil pressure. I would think they would wear gradually.

I think the pump is fairly easy to replace on your car. Is there a small sump at the front of the engine? If so, I think it comes off for access to the pump.

But before you do that, why not test the pressure with a good guage to verify the problem?

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

What type and viscosity of oil are you using? How long since it's been changed?

Oil pressure will tend to drop as oil spends time in the engine.

I found using Mobil 1 15W-50 made a big difference in oil pressure in my M119, especially in summer. Used to show pressures around 0.5 bar at idle in gear, now more like 1.5 bar.

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Steve
'93 400E

0.5 bar would not be considered low oil pressure at idle, but another cause of a sudden change is oil pressure is a bad sending unit.

My oil pressure went to zero at idle, and I was ****ting bricks. The needle would go right back up when the car was moving, though.

It just turned out to be a bad sending unit.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".