I have owned and worked on a lot of cars but I have never seen this happen. My wife came home yesterday and said her oil pressure guage was jumping up and down and the engine was making noise (1990 300SL - 102K mi). I started it up and could hear a couple of noisy lifters but the oil pressure was fine. I took it for a spin and about a block up the road the oil pressure suddenly dropped to zero and the red light came on. Then within 2 seconds it came back out to full pressure. It repeated this 3 times in a short drive so I parked it. By then the lifters had stopped making noise. The oil level is up. This is a new one on me. Has anyone had this happen on the 104 engine? No speculation please, this could be a very expensive problem. Thanks. Craig

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90 300SL Pearl Gray
92 300CE Smoke Silver

Yikes!

No kidding that could be very expensive.

I've never had this happen -- can only be a couple of things: Bad oil pump, bad pressure relief valve, or a serious "leak" in the oil system.

First you need to get a mechanical oil pressure gauge and check the actual pressure in case the electrical sending unit is bad, but I'd guess you will see the same pressures.

Is the low oil light coming on when the pressure is low?

Peter

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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!

What type of oil do you have in it? How long since the last oil change?

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1989 420 SEL

Maybe she left out the part where she had just run over a curb, maybe squashed the oil pan?

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Chas

Had a 380SL, 450SL, 380SEL, 420SEL, 500SEL

Got a Euro 500SEC right now.

I had been running Chevron 20/50 and it had been about a year since change but its not driven much. I changed to 10/40 with a new filter over the weekend but the problem persists. When I first started it the oil pressure quickly came all the way up but after running it for about 2 or 3 minutes it would only come up to about 2 bar and did drop to 0 (even above 1500 RPM - red light came on) and then right back up to about 2 bar (even at 3000 RPM). Shortly there after the lifters started getting noisy so I shut it off. I need to put a mechanical guage on it (even though I suspect that these readings are correct) so if anyone has some info on the correct fitting connections, I would appreciate it. It may be an oil pump/relief valve but I have not heard of this as a problem in this engine. It looks like the pan will come off with the engine in the car but I am not sure. I am not looking forward to this project. At 60, everytime I get under a car not it wrecks my back big time. Craig

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90 300SL Pearl Gray
92 300CE Smoke Silver

As you indicated, the guage is probably working. My first step would be to drop the pan. I did that on my 89 420 SEL and found the tower, from the bottom of the oil pan to the pump, had broken. It is made of rubber, but was rock hard and brittle. There were a few other partsin the pan too, like part of broken rail, which blocked part of the inlet. My pan was dented, so it explains why the tower was broken.

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1989 420 SEL