Oil Pump Failure On 300E. Uncommon?

[Cap'n Carageous]

One of my customers has a 93 300E in his shop. His customer stated that the oil pressure had been low for awhile and eventually went to zero. He drove the car home and it began to knock. He wants a new oil pump installed. My customer asked me to look at it and sure enough, no oil pressure at idle and a knock. The knock sounded like it was coming from under the valve cover. I raised the engine RPM to 2000 and the oil pressure rose to midscale and knock almost dissappeared. O.K. Oil pump is apparently working but pressure ain't what it needs to be. I'm think'in clogged oil pump strainer or collasped oil filter (el cheapo deluxe filter). Anybody with a similar experience?

[pberku]

Change to an Original Mercedes oil filter and try again.

[Jim Anderson]

Isn't there some sort of pressure regulator thing in there?

Big thumbs up to the 'OEM filter' idea. There are a couple of threads on here where that solved the problem.


cheers,
Dan

[suginami]

I was in my former mechanic's shop about 5 years ago, and he had a 90 or 91 300CE on the lift.

He had the oil pan off, and was showing me that the the oil pump had failed or seized. The pan was full of metal shavings.

I didn't ask him what happened to the car, but I assumed he just planned on replacing the oil pump, starting the car, and seeing if there was no other ancilary damage to the engine.

[Cap'n Carageous]

Shop owner flushed the crankcase, changed oil and filter. Oil pressure is now 'decent'. 7.5 lbs at idle and 42 lbs. at 3000 rpm. The rattle is still there. Guys, this thing sounds almost exactly like a diesel or a terrible case of pre-ignition!! We pulled the rocker cover and it's getting plenty of oil trough the cam lube rail and the lifters appear well lubed. Still it rattles. Any ideas?

[engatwork]

What kind of condition is the tensioner in? Were you able to look at it when you removed the valve cover?

i have seen the plastic rail for the timing chain break and cause low oil pressure, there is a small plastic oriface that enters the engine block oil port, if the rail breaks or gets broken at the oriface it will allow oil to flow freely instead of going through the smaller restriction in the rail. see picture

[Cap'n Carageous]

Originally Posted by engatwork

What kind of condition is the tensioner in? Were you able to look at it when you removed the valve cover?

No. With only the rocker cover removed, very little of the timing chain is visible. I tried to stick my finger in to see if there was any slack but didn't even have room for that.

carson356: Great picture! I will forward it to the tech, but I think we have sufficient oil pressure. However you may be on to something. The knocking may be in the timing chain or caused by slack in the chain.

[lkchris]

Originally Posted by Cap'n Carageous

Shop owner flushed the crankcase, changed oil and filter. Oil pressure is now 'decent'. 7.5 lbs at idle and 42 lbs. at 3000 rpm. The rattle is still there. Guys, this thing sounds almost exactly like a diesel or a terrible case of pre-ignition!! We pulled the rocker cover and it's getting plenty of oil trough the cam lube rail and the lifters appear well lubed. Still it rattles. Any ideas?

Yes--needs bottom end rebuild.

Restoration of oil pressure following an incident does not repair the damage done. That noise is not nothing.