boblaird

1992 SL500. After car warms up, oil pressure gauge fluctuates and drops to zero when you let off the pedal or below 1500 rpm. Oil is clean and full and there is no engine noise or change in performance. I need some help please.

Bob

Bigdot

zero is normal when you are not on the gas (or just barely)

only time to get worried is when you are on the gas, and the gauge is at zero.


Mark

Lincoln

Mine does the same thing. Two shops have told me to replace the sender (about $60, I think). I will get mine replaced next time it goes in for service. It was supposed to be replaced last time I had it in the shop but they didn't write it down so it didn't get done.

Bigdot

my mechanic said not to worry about it, my 124 E500, my 124 E420, and my sisters 124 300TE all did it too. gauge drops and moves a lot when idling, then goes up as you accelerate. my jeep wrangler also does it in a way haha

Lincoln

My tech said the same...nothing wrong with the car or oil pressure it's just a funny reading on the gauge. Supposedly replacing the sender will fix the gauge. After replacement the gauge should still jump around a bit at idle and even get near zero but not ever go to zero.

pleeson

Gotta disagree with those mechanics.
In that engine of that era, the problem is likely the failure of the cam oilers, Part# 119 180 02 66
I had same problem and now have normal pressure after the fix.

http://www.mercedesshop.com/shopforu...ight=oil+tubes

Some cars also had a problem with the oil pressure relief valve, in the filter housing.

boblaird

Thanks for all the responses and suggestions. My concern is when it goes to zero the read light briefly comes on. My plan of attack is to work on the easiest solution first and go from there. Sender will be my first replacement. Thanks again everyone.

pleeson

I did the same thins; sender, then relief valve.
When replacing the sender doesn't fix it, don't fear replacing the little oil tubes, it's an easy DIY job, well outlined on the various forums.

ou1954

Oil tubes seem to fit my problem and now, one has really failed . . . tappet noise. Will be a DIY job.


Dealer wants too much, Indi doesn't do that work, but he did replace the sender to no avail. Random fluctuations but never below 1 bar. Clearly the random pressure relates to a broken/leaky oiler tube and the tappet noise confirms it.


Thanks!

davemv

My 1990300SL gone to 0 very briefly while driving, light comes on. Would this likely be sender? Thanks

PeterJ500

Yeah, problem here is that the oil pressure is a little low at idle when it warms up but normal enough for a 29 year old... it also increases as i accelerate on the road but doesn't go over 2.0...

THEN at 2000RPM (under load only) the gauge drops dead and the light comes on... so First I changed the sender, No Difference...
Then I thought I'd install a manual sender / gauge setup, hung the speco over the wiper and took her for a run which showed that the pressure was low and did not go over 2.0 .... and it dropped at 2000rpm under load but slowly and not quite to 0...

After the test drive I put up the car again to see if there was a leak in the line or something and saw what an idiot I am, not noticing that the sump was bashed in, right under the pick-up...
I forgave myself because the dent was so symmetrical that it looked factory oem... LOL

Anyhow, sump off, yes the rubber grommet was dislodged and there was heaps of crap blocking the wire filter... Cleaned it up, put it back together, put new oil, thinking i solved the problem i re-fitted the oem sender and now...... same problem, only the gauge drops at 1500 RPM...

Due to the fact that it was 11.30pm I did not check the oil filter or the pressure relief valve, i also noticed 1 or 2 tappets are clicking on and off, only after she's been driven...

The old girl has been parked since then (5 days ago) but now i read pleeson's write-up, I'm definitely going to investigate the pressure relief valve and the cam feed lines, soon as i get the time...

Thanks champ. I'll let you all know how it turns out Thumbs up