300E PCV Valve

[rich30769]

Cannot seem to find this valve. Can anyone help me locating this piece. Thanks

rich,

You did not say what year. I can respond regarding the M103 engine. There is none. The crankcase is ventilated through the air cleaner directly.

Good luck,

------------------
Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

[rich30769]

Thanks Larry,
It's a 1986 300E. That will explain why I couldn't find it..

[anthonyb]

I'm getting some oil pooling at the top of the air cleaner, where the crankcase vent hose connects, and also inside the air cleaner housing (right under the vent hose connection). I'm pretty clueless about why oil might be coming through this hose - any ideas?

thanks in advance,
anthony

1987 300E

[rich30769]

Anthony,
I'm not a mech. but it could be blow by.. If so, one of the experts or more seasoned mech. could possibly help you with this one. I would like to know also and what measures should be taken.

[jeffsr]

Anthony, if you are seeing oil at the hose connector or inside the air box, then you may have some excessive blowby, although I am sometimes puzzled by some of the design quirks that MBZ puts out there. In this case, the valve cover and engine interior is directly vented to manifold vacuum, ie. it is connected inside the air filter element. Now, I am not a rocket scientist by any stretch of the imagination, but, if you air filter element is dirty or partially clogged, there is going to be a rather high level of vacuum applied to that vent opening, which is going to pull some oil from the area of the valve gear into the air box. At mid to high rpm, all of the action under the valve cover can create an aerosol like mist of oil, and this will get pulled thru the vent. This can happen even if the filter is clean. (the ole path of least resistance). Also, make sure any other openings into the engine interior are fully sealed, ie, oil filler cap, dipstick o-ring. If there is excessive air getting into the interior of the engine, this will create a hurricane inside the valve cover and will increase the oil sucked into the air box.

[anthonyb]

Jeff and Rich, thanks for the replies. This is kind of an elementary question, but what exactly is the definition of "blowby"? I've seen the word used a lot, but haven't yet run across an explanation of what it is.

Jeff - Your explanation makes a lot of sense. I just changed out the air filter a couple of months ago (discovered lots of oil inside when I opened up the air cleaner), so maybe this is just something normal I'll have to clean up on a semi-regular basis.

thanks,

anthony

[jeffsr]

Blowby is an escape of combustion gasses past the rings on the pistons when the rings or cylinder walls are excessively worn, hence the name "blowby" (under the pressure generated by the fuel-air charge, some of the combustion gasses blow past the rings. This hot, nasty gas gets into the crankcase and can cause numerous different problems. To combat this evil force, automotive engineers designed a system called "positive crankcase ventilation" or as we know it "PCV". This system is designed to suck (so to speak) in a positive fashion, all of the evil gases floating around in the crankcase. BTW, these gasses can be very evil. Back in my racing days, we had built a 400 cubic inch Oldsmobile motor for 1380 racing. We were using alcohol for fuel. Well that baby broke a ring during a hard run and filled the crankcase full of alcohol/air combustion charge. When the mag thru a spark at that cylinder, the motor blew up like we had been feeding it c-4. Took out the sump, valve covers, valley cover, caught fire, etc., etc. I wasn't looking at the time, but they told me it made a pretty bluish orange cloud when it went off. So the PVC system makes a lot of sense for a lot of good reasons. Whew!!, too much typing in one day..

[anthonyb]

Wow, good explanation. Thanks for the automotive tech lesson.

anthony