Sorry for bringing up the oil issue.

You're right. It is not an oil issue.

I feel sorry for the owner of this 1994 E420 that has an oil pressure problem with only 80,000 miles....

__________________
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".

psfred - please keep us informed as to the effect of rebuild of pressure relief valve on the low pressure reading. I have a 92 400e with 165K mi (M119 engine) and it has a 0 oil pressure reading when the oil is hot at idle. It also reads 0 BAR doing 75 MPH when hot. It is kind of thrilling. When the oil is cold it reads 3 BAR at idle. I diagnosed the problem to bad sending (sensor) unit since when I placed an analog pressure guage it reads 22 psig when hot at idle, but so far I have not changed the sending unit to fix the problem (placing the analog pressure guage did not involve any oil leak or need to drain the oil). I am waiting for the next oil change to replace the sending unit. I have been driving in this condition for few K miles. I use Mobil1 10W30 but will switch to Mobil1 0W40 on the next oil change.

Did the pressure relief valve cure your low oil pressure problem? My 1992 500sel has same symptoms. Please update as to the cure. Thanks Bill

Yes, it did. Seems that this is fairly common, something goes wrong with the relief valve, so the idle pressure is low. Requires replacement of the whole filter assembly, I believe.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Would you mind giving me more info on this repair? What was cost of parts and labor? Can a diy perform this job? Do you have any available repair procedures or tips available? Thanks Bill

The loggers out here would just say "Hell boy just put a quart of Power Punch in'er". They use Power Punch in all there equiptment ,cars, trucks,garden tractors, transmissions,even automatics.I think they may cook with it...............

William Rogers.......

You must replace the oil filter housing. Difficulty depends on model, but I don't believe it's too bad (I didn't actually do this one, I was asking for a friend who has a shop).

A bit expensive, but cheaper than damaged bearings and crank from low idle oil pressure.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Hi,

I have these same systems on my 1992 300 E 3.0L with 105k miles. Once engine is hot, at idle only, needle drops to around zero. If I bring idle up to 800-1000 rpms, goes to like 1 bar. And once rpms go way up, pressure rises fine.

Does my engine have a oil pressure relief valve or oil sending unit or both? Can't seem to locate in the cd manual I got. Also where would I check oil pressure to verify idle pressure?


Any good way to search the cd manual for appropriate repairs or is there a way to print the full index?

Appreciate the help.

Thanks,

Jeff

Jeff:

There is a relief valve, but I dont' know where it is off hand. A scored seat will do exactly what you see.

I'm also not sure where the oil pressure sending unit is, but that is where you need to attach a working mechanical gauge to check the electric one.

I have an "aftermarket" CD manual and a Mac (so I cannot use the table of contents or index easily), but there is an index burried on one of the CDs, it's eaisre to use that than to look at each and every pdf...

Note that you only need to look in the engine section, under lubrication, so once you determine which group that stuff is in, you only have to look at pdfs with that prefix number.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks Peter,

I located them on the cd. Sensor is near oil filter and relief valve is in the pan. I'll have to get a mechanical gauge on it to check. Till then, I'll lean on the gas at a red light to keep idle at 800 rpm.

Anyone know how hard pulling a pan on 3.0 liter if I need to do that?

Thanks,Jeff