Hi, on my 85 300D air filter housing that connects to the metal pipe on the bottom, it rattles. Is there a seal or gasket that goes on this pipe to connect to the air filter housing? What is this pipe called? Thanks.

That is the S-shaped oil seperator return tube.
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The nipple on the bottom of the airbox should have an o-ring.
The nipple on the oil sump should have an o-ring as well.

I believe the tube should be anchored to the engine block with a tab/bracket and bolt as well.
The bracket has probably failed from metal fatigue with all the engine vibration.

I suspect the tube rattles because the o-rings are missing or deformed and because it has become compressed and effectively shorter from the weight of the heavy vibrating airbox pounding on it for many years


Even if the securing bracket is broken, if you replace the deformed/missing o-rings and straighten the S- shaped oil seperator tube, you will probably eliminate the rattle.

Simply grasp the flared end of tube at the oil sump with one hand, and the flared airbox end of the tube with your other hand and pull them apart to effecively make the tube longer.
The tube is soft and will straighten out enough to remain in place with the friction fit of fresh o-rings and the weight of the airbox on it, even without the third point of attachment of a bracket securing the tube to the engine block.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

That's a BIG picture

On my 85, we replaced the engine with one out of an earlier turbo SD - '82 or '83. The engine does not have the nipple for oil return to sump.

I blocked the air cleaner separator outlet. Then put a small port with plug in the top. I suck any oil out of the separator during oil changes. Some of it no doubt goes into air stream and gets burned. Maybe that is how it was on earlier cars?

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

Sounds like yours is a non-CA 1985. There is a tube below the CA air filter housing, but 2.5"D and better described as a "duct". You probably speak of the ~3/8" D drain tube. The welded bracket which secures it to the lower exhaust manifold bracket often breaks off from shaking. My 1984 300D did, so I re-attached it w/ short pipe strap and nut & bolt. Of course, the air cleaner housing must be off to get in there.

As mentioned, change the O-rings on the tube, including the lower one on the upper-oil-pan nipple. Viton is best. I constantly use my HF O-ring kits (nitrile, viton, HBNR). You must wiggle your arm under the air filter housing as you lower it to slide the upper tube over the drain nipple. If not attached, blow-by oil will just drip down.

BTW, I tired of the shaking air filter and breaking mounts in my 1984, so installed a 1985 CA air filter housing. I used a silicone tee as a mini oil-separator (tube runs back to drain tube), but doesn't work great so the air filter gets oiled. Still, better than the factory design which routed blow-by oil into the turbo inlet.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

Behind the Turbo and below the Exhaust Manifold is an about 4 inch length of steel that attaches to the manifold on the top and the Engine Block on the bottom. It has a hole mid way between the 2 attachment points.

The Breather Drian Tube passes behind that steel metal strap and there is an attachement point on the tube where a bolt and nut can pass through and throught the metal strap to attach it.

Some tubes have a sheetmetal clamp but most have a piece welded to the drain tube.
On mine that bolt and nut were loose and the tube rattled around on others the metal piece breaks off of the tube at the weld and it rattles around and leaks.

In the attached pic the yellow spot is about where the hole is drilled through it. It is easy to view the steel strap from under the Car.

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

Thanks everyone, I apologize for the big picture. Do you know the part number or the type of o-ring I should get? From the descriptions, there will be two o-ring?