OM 606 Oil Change...order of operations does count! - PeachParts Mercedes-Benz Forum

nhdoc · #1 09-13-2006, 01:49 PM

As test I lifted the car and drained the oil today out the drain plug on my '98E300. When it had just about stopped running out I hand tightened the plug and lowered the car, removed the filter and replaced it along with the 3 o-rings.

When I lifted the car back up and removed the plug another 1/2 quart or so of oil came out...lesson learned...if you're changing the oil on the OM606 (or probably any top-filtered car) changed the filter FIRST and let the old oil trapped in the filter housing drop into the sump before draining or else you'll leave 1/2 quart or so of old oil in the sump if you drain first without changing the filter while it is still draining.

Since I have seen techs do exactly that I know they don't realize there is a difference in the order in which you do them, but now I have confirmed it definitely does matter.

This probably explains why my first oil change seemed to only require about 7 quarts while these last 2 took 8. I probably drained, then changed the filter and left some old oil in there that time.

Wes Bender · #2 09-13-2006, 01:59 PM

Same thing holds true for the older engines too. The FSM specifies to pull the oil filter first. Most "quicky" oil change places don't do this and you wind up with a fair amount of dirty oil left in the engine..... (Of course, if you use any of these places for your oil changes, you deserve what you get!)

Cheers,
Wes

vstech · #3 09-13-2006, 02:34 PM

if I raise my SD up by the front, with the rear tires on the ground, the engine tilts at a pretty steep angle, I bet there is at least 1 qt left in the pan with that tilt. then if you lowered the motor to get to the filter, changed it, and raised it back up to check the plug, I bet oil from the back of the pan as well as from the filter housing would be evident.
so, I wonder if it is oil in the filter housing, or mostly from the rear of the pan?
Hmm.
That is why i posted the earlier question about how best to drain the oil.
John

nhdoc · #4 09-13-2006, 03:39 PM

Quote:

Originally Posted by vstech

if I raise my SD up by the front, with the rear tires on the ground, the engine tilts at a pretty steep angle, I bet there is at least 1 qt left in the pan with that tilt. then if you lowered the motor to get to the filter, changed it, and raised it back up to check the plug, I bet oil from the back of the pan as well as from the filter housing would be evident.
so, I wonder if it is oil in the filter housing, or mostly from the rear of the pan?
Hmm.
That is why i posted the earlier question about how best to drain the oil.
John

No it is oil from the filter housing that drains out. Apparently there is a "reservoir" of oil that drains when you remove the filter holder. My car was on a lift the whole time, dead level so the only oil that came down after my initial drain was from the filter housing itself. Besides, on the 606 the drain plug is not on the back but on the side of the crankcase, toward the front.

pawoSD · #5 09-13-2006, 03:52 PM

On our 617's I always: drive the car up on a couple 2x4's in front so I can get under it a little easier.....(an extra 4" of headroom)....then I open the filter housing, pull the filter, then I pull the plug underneath, leave it draining about 15 minutes, put drain plug in, put new filter in, close up filter housing/tighten bolts, pour in oil, run 3 minutes, stop, wait a few, check level, add any if needed, then close it all up.

scott19_68 · #6 09-13-2006, 05:02 PM

I don't mean to hijack this thread but on a similiar topic: I've always used the suction method and evacuated the oil out the dipstick tube. While waiting for this to finish, I usually pull the pull the oil filter and replace it & the O-rings. Am I most likely getting all the old oil or is there a resevior somewhere that the "down the dipstick tube" method is missing?

nhdoc · #7 09-13-2006, 05:21 PM

Quote:

Originally Posted by scott19_68

I don't mean to hijack this thread but on a similiar topic: I've always used the suction method and evacuated the oil out the dipstick tube. While waiting for this to finish, I usually pull the pull the oil filter and replace it & the O-rings. Am I most likely getting all the old oil or is there a resevior somewhere that the "down the dipstick tube" method is missing?

I think as long as you pull the filter while drawing out the oil you'll get nearly all of it. I also have used that method but frankly prefer the old gravity drain better (not to start ANOTHER thread on which way is better). You will never get as much out with the vac method as with the drain method but it probably doesn't matter...I prefer the drain method mostly cause it gives me a reason to examine everything underneath...it's how I found leaks in the oil level sensor and thermostat housing that would have otherwise gone un-noticed.