82 300DT Oil Pressure Questions - PeachParts Mercedes-Benz Forum

dieseldan44 · #1 11-18-2006, 07:45 PM

hey guys - i searched a bit in the archive but I want to get some opinions on what I am seeing. this is my first day with a W123 (or a MB or a diesel - as i say newbie alert), so go easy on me.

when i got the car, the oil was ~2.5 quarts down to begin with. i don't yet know the ultimate origin of this. i refilled with Rotella 15W40 this am.

started the car and oil pressure shot up to 3. good. went driving for a while and noticed the pressure start to drop to about 1.75 when off the accelerator. as soon as i go back to the accelerator the pressure shoots right back up to 3.

is this ok? i have read so far people dont like their gauge go under 2, ever.

there are 3 small oil leaks i have noticed so far.
1.) the passenger side line that goes from the bottom of the radiator to the oil pan. looks to be that junction. small amount of dripping after driving.
2.) oil seemps out of the filler cap, enough to be seeping down the side of the valve cover after my 20 minute drive. does this mean i just need a new filler cap?
3.) some oil on the air filter. lots to read in the archives on this.

my ultimate question is am i in major danger? would the leaks be causing be causing that lack of oil pressure after its warmed up?

thanks for all the help,
dd

#2 11-18-2006, 08:00 PM

Quote:

Originally Posted by dieseldan44

is this ok? i have read so far people dont like their gauge go under 2, ever.

there are 3 small oil leaks i have noticed so far.
1.) the passenger side line that goes from the bottom of the radiator to the oil pan. looks to be that junction. small amount of dripping after driving.

Pegged gauge is normal. Factory manual says it can drop as low as 0.3 bar at idle and should peg again before you reach 3000rpm.

The line going to the radiator is the transmission cooler. Check your ATF level asap.

ImBroke · #3 11-18-2006, 08:00 PM

DD, congrats on your purchase. Hopefully you'll enjoy your Mercedes Benz.

Oil pressure sounds normal to just a little bit low. Possibly nothing to worry about. If you don't know what kind of oil is in there now, definitely do a change soon, with a diesel oil. Since your pressure is just a little on the low side, could be someone just threw in some possibly straight weight oil. Never know unless you change it yourself, or have good records. Sounds like normal seepage around the fill cap. The newer plastic ones don't seem to seep like the older metal ones. Could need a new sealing ring on the inside of the cap. But, I don't know if they have them available. I'd go with a new cap. A little oil on the air filter is normal also. The one thing I'd be concerned with is the possible oil cooler line problem.

ImBroke · #4 11-18-2006, 08:01 PM

Looks like I was a touch too late... Congrats FI.

dieseldan44 · #5 11-18-2006, 08:46 PM

will check ATF tomorrow first thing. maybe i have not properly isolated the oil leak in that region yet, i shouldn't get engine oil leaking from that cooler line? must it be leaking from somewhere else up above? (btw, the one on the passengers side of the pan is the one thats leaking...

will update when i go back to it tomorrow...

#6 11-18-2006, 08:53 PM

Quote:

Originally Posted by dieseldan44

(btw, the one on the passengers side of the pan is the one thats leaking...

It could be the ATF cooler line (The ATF may be brown/black if it's old oil) it could also be one of the oil return lines in that area (The turbo and CCV oil from the air filter drain into the oil pan on the passenger side.).

dieseldan44 · #7 11-19-2006, 09:54 PM

the ATF fluids was fine, red and full.

oil pressure was stable driving, 1.5 at idle after warm.

i still have oil leaking from somewhere above the passenger side of the block. ill prob need to steam clean to track it down - i just cant see where its coming from. might be the oil return line...cant tell yet.

-dd