Elementary oil change question - shaft in filter housing

[cmac2012]

I've already done this once on my car and I'm thinking, why not listen to a description of it, might learn something. So I found my favorite happy German guy at Diesel Mercedes who laid out his routine.

At one point he said that one thing that is often neglected is an examination of the tiny hole on the shaft, up near the cover flange. He said one needs to check to see that it is not blocked so that oil can run freely down the shaft and out the hole at the bottom. Sure enough, I didn't do that last time.

Turning it over one can see oil ooze out the hole, a good sign I would think, but the part that puzzles me is I'm unable to blow any air through the tube, this from affixing my mouth on the mostly cleaned off end port. No sign of any increased tendency for oil to come out of the hole in response to my lungs pushing on it. Does anyone know, is there any sort of one way valve in that tube? Because something doesn't seem right.

I thought to put the little rubber end on one of my air spray nozzles on that little hole and see if oil or air blows out in the opposite direction, I might give that a go.

Exciting video of the piece and action in question:

https://www.youtube.com/watch?v=DEx4zNUD1bc&feature=youtu.be

[Diseasel300]

There's a check valve (ball bearing) in the tube. Trying to blow up it won't pass any air. You have to blow air through in the direction of fluid flow - from the hole in the top of the stem down to the oil pan (hole in the bottom of the shaft). The hole in the stem is to allow the oil from the bypass part of the filter (fine polishing) to pass back to the oil pan.

[cmac2012]

Oh man, THAT is the answer I was wanting. Nothing else made sense, other than major internal blockage. I used a short piece of rubber tubing to see if I could blow air through the tiny hole in question - can't get my mouth on it - didn't blow discernible air. Oh well, I'm putting it in.

But thanks for your quick reply.

[Diesel911]

On my 84 300D the upper part of the Oil filter is the bypass part of the Oil Filter. The Oil that goes through that little hole goes down that shaft, past the check valve and into the Oil Pan.

That check valve also slows the Oil from draining out of the Oil Filter Housing like when you park and go grocery shopping so that the whole Oil Filter Housing does not have to be refilled each time.Why those 2 little o-rings need to be replaced sometimes.

I don't know how to take mine apart as I have never tried but long ago one of our members said he found stringy cotton stuck in his check valve. The bypass part of the Filter is full of waste cotton.