Oil Pump? Or something else?

[brewtoo]

I wrote recently about a sudden total loss of oil pressure in a 1990 300E 3.0.

My aural "alarm" was the engine rattling. Only then did I notice the oil pressure gauge was on zero.

I drained five quarts of oil from the engine and I have lowered the oil pan enough to see that the drive chain for the oil pump is intact and in place. Next is raising the engine to get the oil pan off.

BUT...I started wondering...Before I go after the oil pump, is there ANYTHING else that could cause a total loss of oil pressure?

BTW, I think there's enough bolts holding that oil sump on to build a whole car!

Thanks

[mctwin2kman]

Crap filter or clogged filter can cause loss of oil pressure. I had a cheapo filter I bought once when I was not thinking. Did the oil and filter change and a few months later I noticed my oil pressure starting to suck. Changed the filter first and regained my oil pressure. Too bad I had a lifter go bad as well but oh well it did not take long to fix that.

[brewtoo]

Originally Posted by mctwin2kman

Crap filter or clogged filter can cause loss of oil pressure. I had a cheapo filter I bought once when I was not thinking.

The oil filter is a Bosch. My oil pressure went away suddenly, like flipping a switch.

Thanks

[Fourings]

I don't know exactly how it works on the 103 engine, but almost all engines have a spring loaded valve to bypass the filter if it should become clogged. Malfunctioning valve perhaps?

[t walgamuth]

is the pickup screen could have clogged but that seems unlikely.

tom w

Make sure the oilpan has nothing in it that could plug up the pickup-tube screen. Might wanna do an autopsy on the oil filter itself. If you are SURE you heard a difference, then the oil pressure sensor is unlikely, but i'd want to cover all bases before taking that pan off...specially if your pump behind the timing chain cover like mine is! I've only heard of one MB oil pump going...they are so dead simple, just two gears, failure is almost impossible.

cheers,
dan r.

ps. lay the bolts out on a piece of cardboard with an outline of the oil pan on it...the bolts will likely be different sizes, so you don't wanna just toss 'em in a coffee can.

[brewtoo]

If you are SURE you heard a difference, then the oil pressure sensor is unlikely,

I'm afraid I heard the engine start rattling, which made me look at the gauge, which was on zero. I did start the engine for a second after I had shut it down and it was definitely rattling...probably the lifters. There is no doubt that this engine has NO oil pressure.

Just want to be reasonably sure that there is no other possibility than the pump before I go to the trouble to remove it. Whatever the cause, I'm hoping that the engine has survived the trauma.

I agree, the pump is so simple a failure seems unlikely, but I can't think of anything else that could cause these symptoms.

Thanks