low oil pressure at idle
 

well today i changed the oil and i noticed that the car's oil pressure gauge still falls to '2' when stopped at a stoplight or similar situation. it goes right back to '3' when the accelerator is hit. it was doing this before the change too. i checked the levels - fine. is this normal or should i be doing something differently?

at idle i believe the manual says anything down to 1/2 is normal. you are fine. a good engine will go down to about 1.5 at idle when good and hot. so you are very good.

tom w

Mines been down at about .9 to 1.1 bar when its hot (at idle) and close to 2 when its cooler outside and I'm not driving it hard, I am going to replace the little rubber o-rings on the oil filter cover stem when I have it out in week or two....they were pretty hard last time, its probably time.

O Rings
 

I gotta ask. What little rubber O rings on a shaft are you referring to? Are these around the shaft that goes inside the filter all the way down the center? and if so are 240D's supposed to have any on this shaft? I did my first ever oil change a few weeks back and there were no such o-rings in sight.

- Peter.

Yes, the 240D has them and they need to be replaced every couple of years anyway. You might have old ones on yours and not have realized that they were rubber because they were so petrified.

Len

Yeah in my observations it seems good to replace them every 3-4 oil changes as by the 3rd they're getting hard, and by the 4th, they're rock hard/need replacement. Since they are only like .33 cents apiece, its not that big of a deal. :D

I would say so. I would not worry about "2" at idle. Especially considering that my car is at "0", yes ZERO, when it is at hot idle (above 100°C) when in drive. :D When in park at hot idle, it is around "1". It is back up to "3" when I accelerate, but not until 1800 RPMS. My owners manual says that ".3" is OK at hot idle. My car is just a old work car though, with 266K. I do not care... I will drive it until it stops. Still does not use (or leak) any oil between oil changes. I am amazed. Perhaps the oil sender is on the fritz.

Is this while in "PARK/NEUTRAL" or in "DRIVE/REVERSE"?
Thanks Tom.....

Mine pegs at three until it gets warm, then drops down to two. When its been running for half an hour or so, or its really hot outside, then it drops down to 1.5.

1-2bar with hot oil is normal for me.

Unless I'm blind or really ignorant mine definately doesnt have them on there at all. I'll look really closely again wen I do my next oil change in about 280 miles. If they are really not there I'll have to put new ones on. Does not haveing them do any harm?

- Peter.

Yeah as long as you dont get them from a MBZ dealer.....$3.24 each!!!!! Yikes!

But do change them. If oil is getting past them then it is just dumping back down into the oil pan.

I suspect it would cause some of the oil to bypass the filter.

Jeremy

can you use 'regular' o-rings?

I have a box of assorted O Rings I used to fix the A/C in the Mercedes (and several other cars on the block since they saw me working on it).

Can those Orings do? Or is it a special high temp deal?

Thanks! :)

I was just about to post this as I'd like to do the same if the a/c o-rings will work. I'm getting ready for a major overhaul and I'll have some o-rings left over.