Oil Separator on M104 - PeachParts Mercedes-Benz Forum

bwheitman · #1 02-25-2005, 01:16 PM

Hey Friends,
If anyone has experience with these oil separators for the 104, I would appreciate your help! 96 SL320 with 128k.
The problem I have is there is a lot of oil coming out of the port of the oil/air separator on the bottom of my engine. (near the front where the AC compressor mounts) I have had the mount/separator removed before and everything looked fine, but I am getting a lot of oil, more than I would think is good for my intake valves. It is so bad it is leaking down the side of the separator. Any ideas? I had put a filter in there to catch the oil and that would clog up after about 1000 miles, so I took it out, is there something wrong with my engine? The engine runs fine, no problems with anything, my oil pressure has been higher than normal at 2.75 at idle and 3 anything higher, it is 3 when cold. I switched to syn about 6 mos ago and it has been higher ever since. Any ideas? Thanks for any suggestions.
Brian

bwheitman · #2 02-26-2005, 07:33 PM

I cleaned my throttle body and then re-attached my filter in between the oil separator and the manifold to reduce the amount of oil getting into the intake. Thanks,
Brian

tower · #3 02-26-2005, 08:06 PM

Have you checked the engine for blow by or a plugged egr system?

bwheitman · #4 02-26-2005, 08:21 PM

hmmm,
I have heard the term of "blow by" but don't know how to check for it or exactly what it is. Also I replaced my EGR valve and all vacuum lines about 6 months ago because I got a CEL code on it. It has not come on since, but I have heard about the EGR line getting clogged with carbon, how can I check that? remove the line from the EGR valve and blow in it to see if air moves freely? Thanks for the response, I will look up the EGR system on the 104 and see what I can find, if you have any other advice let me know.
Brian

bwheitman · #5 02-26-2005, 11:18 PM

I checked my EGR, I pulled it off and applied vacuum and it opened. The port from the exhaust manifold was clear, and the port from the EGR valve to the Intake manifold was clear too. There is another valve in front of the EGR that goes to the air pump and then into the side of the head, whatever that is, it is working as well, when the engine is under operating temp the electric air pump kicks in. I may be over-reacting because I remember someone saying it is normal for the 104 to get oil in the bottom of the intake manifold, maybe I just didn't get the hose from the oil separator to the manifold on tight enough and it allowed oil to leak out. But as I understand the diagrams it is not supposed to allow oil up that line into the manifold, so who knows. The engine is in perfect running order, compression is almost at 10 on all cylinders, oil pressure is perfect, I don't know. I remember my diesel 140 was doing the same thing, hmmm interesting problem. I guess it is time to take it to the dealer and ask someone to look at it.
Brian

tower · #6 02-27-2005, 07:15 AM

Blow by to me is when the rings get weak (or cylinder taper to large) that the exhaust gases can escape past the rings. It causes more positive pressure inside the engine than what the PCV system can handle. In the past (long past I might add), some seepage was expected and the PCV system accomodated it at the benefit of reduced NOX at the tail pipe.

Check around the oil dipstick because if you are getting alot of pressure it will push oil past the o-ring of the dip stick and coat the outside top of the dipstick.

Only solution I'm aware of if is a lower end rebuild (rings/re hone cylinder to remove taper) I'm afraid.

I'm really not an expert on this area so hopefully someone will chirp in and correct any errors I've said.

Ron.

PS. I wrecked an 89 Volvo because I couldn't get the oil seperator to cut down on its weeping. Figured it was blowby. Didn't bother me much because I only paid $2k for the car and drove it for over 2 years.

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