Does anyone know part # or size of this O-Ring? - Page 2 - PeachParts Mercedes-Benz Forum

BillGrissom · #16 08-02-2016, 05:45 PM

Post 2 is right on. O-rings aren't rocket science.

On my 1984 300D "air filter drain tube", I used an O-ring from a Harbor Freight kit, probably Buna-N and I recall I have a metric kit. But, an inch size would probably work too. Viton would be best. That tube has an upward-facing funnel, so you don't need a perfect seal unless you have unusual blow-by, unlike the crazy upside-down funnel at the other end (upper oil pan) and the turbo drain tubes.

greazzer · #17 08-02-2016, 06:30 PM

No, it's obviously not rocket scientist but in this instance the 'correct' part is probably the best route to take versus grabbing one which looks about right. That is why I reached out to the forum.

Here's the OEM nipple off the original air-oil separator, which is grafted onto the MANN-ProVent 200. Looking for a spare dipstick O-ring in the garage since that might be it.

leathermang · #18 08-02-2016, 06:58 PM

Sometimes o rings are rocket science... that is what broke the Challenger in 1986...
I think Harbor Freight has two boxes of assorted o rings available... us and foreign.. lol

Why are you assuming that the ' correct' oring is not included in THIS set ?

O-Ring Assortment Pack - 397 Piece Metric O-Ring Assortment

greazzer · #19 08-02-2016, 08:36 PM

I just cracked the code. It is in fact the O-ring (same) which goes to the dip stick.

The outside dimensions of the dipstick tube (metal) is exactly the same as the oil drain tube. Good thing I have a spare dipstick tube to line them up. The plastic dipstick has almost the same exact diameter as the nipple part on the separator. It could be precisely the same, but I cannot find my good micrometer, so used my HF one.

So, for those folks who may end up needing to replace that O-ring on their OEM air-oil separator or do a tiny mod on the MANN-ProVent 200, the correct O-ring is the following:

0069972645

And yes, it made a difference getting the correct O-ring. Not rocket science at all. Just luck finding my spare metal dipstick tube, lining it up, and a quick measurement. It popped in there like the OEM one did, it is not 'too' tight, and holds its place with just enough allowable movement. On this one, I wanted to replicate what the German engineers did with the fitment. I got a much better solution as to the separator, but I needed the factory finish so to speak when it came to the seal. Seals are sometimes important.