My mechanic told me I needed to have the crankcase ventilation system cleaned out on my 1991 300 CE - M104 Engine...I want to know if this job is something I can do myself and save money....does anyone know what the scope of work involves or how to do it? Thanks
Are you sure your mechanic said crankcase ventilation system? Maybe the egr system I could understand, but your crankcase vent system consist of the large hose next to your oil fill cap that runs from the cam cover to the air filter housing. That's a pretty big hole inside that hose to be "clogged".
I would get a little more information from your mechanic or get another mechanic.
You are probably right about that, he's a great mechanic; and its most likely my terminology error...he said he would have to remove the intake manifold to get to all the places to be cleaned out...$700 bucks...so, I thought if I researched the system, it may be a job that I'm up for myself to save bucks...
I been workin on cars a long time, but I just want to fully understand the parts and what needs to be cleaned out...if you have any info on this, I would be very grateful...
i think on the M104 its two wholes located ontop of the spark plug cover... the ID (inner diameter) is a little less then 1 inch so its very hard for them to clog up... i just used some paper towels and cleaned it out... it wasnt really clogged but its good to be on the safe side...
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300E 1993 121k MILES (MINE)
S500 2004 4 Matic 37,000 MILES (mine)
BMW 750Li 2007 15,700 MILES (Dad)
Lexus GS460 (Mom) 9,000 MILES (too much power)
2007 E350 4 Matic (Side Car) 11000 MILES
07 STi with a bit of work done to her... (brothers)
Hi, actually there is a crankcase ventilation system, wich contains of a "oiltrap" located in the area just under the waterpump. From this area there is a hose running up to the cylinder head. Its connected to the head under the intake mainfold, inside there is a 2mm hole that lets the gases recirculate back into the intake. This 2mm hole was completely clogged on mine. I´m not sure, but i dont think its possible to clean this without taking the intake mainfold off.
Hi, if the ventilation doesn´t work you will get increast crankcase pressure. This means that oilmixed air from crankcase will instead pass trough the hose into the airfilter instead of passing the oiltrap. In my case that was one of the reasons for high oilconsumption.
ALL gasoline engines produce "blow-by". Blow-by is fuel vapors that slip past the piston rings, and into the crank case. These MUST be removed, elsewise you will accumulate too much gasoline in the oil, diluting it, and turning it into a solvent , and soon your engine will seize up due to lack of lubrication.
So.........
Clean fresh air is drawn in from the air cleaner, thru that big hose, and down into the crankcase.
It is done by having a vacuum source from the intake. In your engine (and mine), this is done be the 2mm hole mentioned from previous poster.
The intake manifold must be removed to access the hole. The mechanic will also make sure the entire system and passages is cleaned.
__________________ 1990 300CE. Garage kept all its life. Looks & Runs Like New. Everything works. White w/Palomino int. 17" Enkei LX-F Chrome wheels w/Falken Azenis ST-115 225-45 tires. Tinted windows. Black sports grill w/Euro clear front lamps. Me, ASE Master Tech, 25yrs.
The Way It works 
1990 300CE. Garage kept all its life. Looks & Runs Like New. Everything works. White w/Palomino int. 17" Enkei LX-F Chrome wheels w/Falken Azenis ST-115 225-45 tires. Tinted windows. Black sports grill w/Euro clear front lamps. Me, ASE Master Tech, 25yrs.
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