450SEL 6.9 oil pressure - PeachParts Mercedes-Benz Forum

alabbasi · #1 03-07-2011, 11:09 AM

I've been having some issues with the oil pressure in my 6.9. First symptoms that I saw was that the oil pressure would raise on start up but then drop (to about 1 bar whether you're idle or driving) until the engine warms before returning back to normal.

This is a dry sump system with a separate oil bag in the fender that contains most of the oil (although there is a sump).

Most recently, I noticed while driving fast over a fly-over that connects one highway close to my house to another. There is a fairly sharp turn which I hit at about 60mph.

I had full oil pressure going into the turn, but as soon as I hit the turn, the pressure dropped from 3 bar to 2 bar and returned back to full pressure when I came out.

This obviously should not happen in a dry sump system so what does say?

Would this indicate a feed problem in the hose (blockage)?
Is there a separate dry sump pump that may not be working?

mbdoc · #2 03-08-2011, 08:31 AM

When was the last oil change?
Sounds like either oil foaming OR the dry sump reservoir isn't
allowing proper flow back to the oil pump.

alabbasi · #3 03-08-2011, 01:14 PM

Foaming has taken place, I also posted to the M-100 Forum and got the following response which seems to be the exact symptom.

"Al: Had exact same symptoms, foaming and drop in pressure on turns. Were you making a left hand turn by any chance? Turned out to be rubber seal midway on the front flange fitting which seals the gap between the pump and the sump wall thusly allowing oil to drop into the sump breaking suction hence the drop in pressure and foaming. Easy fix."

Now i need to find out which part he is referring to as it's not obvious to me.

Thanks for your help.