Air filter oil tube: 1982 vs 1985 300TDT - PeachParts Mercedes-Benz Forum

300TD1982 · #1 11-01-2014, 08:29 PM

Hi, my car is a 1982 w123 body with a 1985 engine. w123 300TDT OM617.952

My question is: Does the 1985 engine have an oil return tube from the air filter to the engine? Someone said that it does not.

I took off the air filter today for the first time to try to find the exhaust leak. It turns out that there is no oil tube, just an open hole in the bottom of the filter housing. My blowby was puffing out the bottom!

Is it true that the 1985's don't have an oil return from the air filter to the engine? If they don't, where does the separated oil go?

Many thanks!

Zacharias · #2 11-01-2014, 08:51 PM

My understanding is that the 1985 California-spec w123 had a completely different "coffee can" air filter housing and filter element that sat at the front of the engine bay, to accommodate the space taken up by the CA the emissions equipment. So there would have been some alternative plumbing arrangement for the oil drain.

If the 1985 motor that was installed was a CA-spec one, then it sounds like someone bolted on the 1982 manifold.

That's as far as I can assist. I've attached a pic.

ROLLGUY · #3 11-02-2014, 12:11 AM

If you have the 49 state air cleaner and manifolds on your '85 block, then you probably don't have the drain tube. The OM617 with CA emissions does not have a connection for the oil separator drain tube in the upper pan. The crankcase vent tube was fed directly into the turbo air intake tube (photo in above post). On the early 116's and I think 1981 126's, it had the breather tube "T'd" into the "U" tube (not to be confused with the leading internet video site). That might be the best thing for you to do in your situation. I have an '81 300SD with that system, and can get a photo for you if you would like.....Rich

charmalu · #4 11-02-2014, 01:57 AM

As Rollguy mentioned, the W116 78 - 80 had the blow by tube plumbed directly into the "U" Tube going into the Turbo from the Air Filter housing.
If you can locate one from the junk yard or if someone has one that would be your best bet.

The other thing would be adding an oil catch can and then running it into the "U" Tube if you don`t want the oil vapors going to the Turbo direct. wont`t hurt anything if it does.

85 Kali engine had some differences compared to the 84 and older 617.952. mostly the bolt on attachments, and as you discovered, no drain tube in the upper pan. The crank had a 34mm hole compared to the other engines having a 35mm hole. so if you want to install a manual trans, there is no Pilot bearing that will fit.

Charlie

300TD1982 · #5 11-02-2014, 01:41 PM

Thanks all!!! That is very helpful info.

My biggest fear was that there was an unplugged hole that the drain tube was supposed to plug into in the oil pan! That sounded bad. So I'm glad to hear the '85 Cali engine doesn't have that.

I'm cool with the auto transmission. Thanks for the info about the crank sizes though. In time I'll compile a list of w123 1985 differences and post it here on DD if it hasn't been done. Doesn't seem to be in my copy of the FSM.

I'll probably run a catch can.

What about running a hose from the valve cover to a catch can, and then a hose from the catch can to the top of the air filter housing?

Or, my U tube has a flat spot, what about tapping there to feed the fumes?

Then again, I could just vent it straight to the ground? Or does the crankcase prefer the vacuum?

I'm loving this car! Thanks for helping!

ROLLGUY · #6 11-02-2014, 02:42 PM

Quote:

Originally Posted by 300TD1982

What about running a hose from the valve cover to a catch can, and then a hose from the catch can to the top of the air filter housing?

Or, my U tube has a flat spot, what about tapping there to feed the fumes?

The connection on the top of the air filter housing is the inlet to the oil separator. If you were to just plug the nipple that is sticking down from the air cleaner housing, the crankcase gasses will just be sucked into the turbo like normal, and the oil separator would fill up with oil. You could just run a hose from the nipple into a catch can, and the vapors should be hosed to a hole drilled into the U tube on the flat spot that you mentioned (the early cars just had a grommet that the hose slipped into).

Diesel911 · #7 11-02-2014, 04:25 PM

Quote:

Originally Posted by 300TD1982

Hi, my car is a 1982 w123 body with a 1985 engine. w123 300TDT OM617.952

My question is: Does the 1985 engine have an oil return tube from the air filter to the engine? Someone said that it does not.

I took off the air filter today for the first time to try to find the exhaust leak. It turns out that there is no oil tube, just an open hole in the bottom of the filter housing. My blowby was puffing out the bottom!

Is it true that the 1985's don't have an oil return from the air filter to the engine? If they don't, where does the separated oil go?

Many thanks!

At the bottom of the Turbo Drain Tube and between the Engine see if there is another Nipple there. If so you have found the bottom end of where the Air Filter Breater Drain Tube can be attached.