I went to change oil and filter and the filter unscrews, but then won't come off. It is the correct Mann filter and maybe the 4th of the case that I bought. I tried a gentle pry, but that did nothing. I was able to screw it back on OK. I can live with it for awhile as it only has 5 k on it. This was in preparation for a 2 k trip next week. Any suggestion would be very welcome. TIA

You probably have a collapsed engine mount. The clearance for the oil filter on a 940 is very small. They are a pain in the rear to get off when the mounts are fine. If one of the hydrolic mounts colapses, then they will become almost impossible to get out. Check out the Faq on mounts and see what you think about yours.
-Gil
in CT

This happened to me with wife's 240.

Problem was collapsed motor mount.

Temporary fix was to jack up the motor a bit to provide clearance for removing and installing new filter.

This doesnt make any sense to me either, unless you mean that it unscrews a bit and then runs into something, like the frame, so you can't pull it away from the block far enough to get it off. I've *never* seen an oil filter get crossthreaded or screwed up in any way other than a little abuse from a filter wrench (when they're REALLY REALLY stuck!) and I've seen a lot of oil filters.

I guess given the proximity to the right frame rail, if the engine mount failed and let the engine sag A LOT, then you could have an issue with insufficient space to remove the filter. Even then I don't see how... .it's pretty easy to get out on my 740, and that has tired engine mounts.

The only other (remote) possibility, and I bring it up because it actually happened to my wife's '75 164E 15 years ago... Midas built a "custom" exhaust for it, and we used PH8A filters (the big oil filter!) and we were able to remove the filter from the engine, but not extract it from the space it was in. The stupid exhaust arrangement they invented prevented me from getting the filter out! That was a surprise to say the least.... I screwed it back on after draining it out. Now, I'd probably do one of two things... either jack up the engine to get it out and install a short Mann filter, or go back to Midas and tell them they're a bunch of hamfisted knuckleheads, which they are, and make 'em fix it right.
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total

I'm with Bram. I don't get it. How could it screw back on?

I would try prying with a piece of stiff plastic or maybe wood, while you unscrew it.
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http://www.fidalgo.net/~brook4/oilslubesfilters.html

What exactly do you mean "unscrews but won't come off" ? It's threaded onto a hollow tube in the block, so if it turns on that it's bound to come off the block face.

Bram

Bram and the others.
That's what I thought too. Just for some reference to show that I do have some mechanical experience, I was a professional BMW motorcycle mechanic 100 years ago in another life. I did this to the point of becoming one of the top few BMW dealers in the country. Lots of BMW info on my web site at w6rec.com I have done all of my oil changing just about my whole life and have never seen this one. My private shop has a oil pit just for this type of work. So, I feel really stupid even asking about this.
The filter unscrews normally out to the end of the threads, maybe 3/8" or so. Then is is slightly loose, but won't pull off. It isn't hitting anything that I can see, it just won't come off. Nothing is cross threaded and it goes back on easily as it should. I already tried to pry if off, but didn't put enough pressure to distort the filter.
Does this shot motor mount make the filter hit something so that it won't pull off? I will check again on that one. The car is in great condition and very clean. I do get about one drop of oil coming from the filter area and after a couple of months it has spread out to a circle 12" across on the floor. I don't think that this has anything to do with the filter not coming off. The "leak" is so minor that I have just been lazy to fix it. Besides, it is my wife's car.