(?) O-rings w/ oil change (240d) - PeachParts Mercedes-Benz Forum

Miles81_240d · #1 05-22-2002, 02:34 PM

Hello All,

Just did my 3rd oil change (since getting my car) last night on my 240d.. I keep seeing mentions on the board on how important it is to periodically 'replace the rubber o-rings'.. I think tho.. that i am missing them (?). The filters i have been using (Knecht/Mahle) have rubber pieces pressed in them on the top and bottom sections, are these the "o-rings" people are referring to? One forum posting sounded like there is supposed to be a o-ring on the bottom of a shaft somewhere (is it the canister lid shaft?) My canister lid does not seem to have any o-ring at all near at its base of the shaft. is this a bad thing? I do have a slightly noisy lifter tick it seems at times....

I greatly appreciate any help any of you can give on this.... thanks!

Miles
1980 Silver 240d

Miles81_240d · #2 05-22-2002, 03:32 PM

Thanks for the info, Bill!,

Have i caused damage by not having the o-rings in place? [is the engine being starved of oil?] i'd say the car has been this way for approx. 5k miles.. I hope to get some replacements as soon as possible. would a MB dealer have them likely?

thanks so much for all you help!,

Miles

JimSmith · #3 05-22-2002, 03:41 PM

Miles81_240d

Attached is a cross section of the flow path in the filter and housing. The o-rings are items number 24 and 25, and, it is possible you are allowing the engine to run without oil flow to the bearings and so on until the filter housing fills with oil since the contents of the housing at engine shut down will drain through the unsealed area, and down through passage "c" to the oil pan. It is also likely that some of the pressurized oil is short circuiting the path out passage "b" which leads to the bearings and returning to the oil pan through passage "c" as well. If your oil pressure is coming up quickly and the pressure is steady you may be ok, but I would not leave these o-rings out of the assembly any longer. Hope this helps, Jim

Miles81_240d · #4 05-22-2002, 03:54 PM

I second the Thanks! =) this is such a wonderful group! I will pick up some o-rings today....
Thank you all so much for the help!

-Miles

leathermang · #5 05-22-2002, 04:04 PM

So, JimSmith, did you admit defeat on the oil filter pentagon effect ?

Maybe a lack of these orings would cause that ???

Greg

JimSmith · #6 05-22-2002, 05:13 PM

Greg,

It seems the one that was dissected had no center grommet at all. Or at least none was recalled, and that would have caused the sequence of events I was describing. I think TXBill noted he has seen filters with the center grommet loose inside the filter, which would also be a way for the bypass flow that normally exits down the center tube and passage "c" to avoid that high resistance path (look at the orifice the flow has to go through at the top of the center tube next time you change oil) and join the main flow. Such conditions would make the holes in the sheetmetal can on the bypass filter section be the throttling element of that new flow path, and cause the outer can to collapse. The idea that I proposed that the inner can might deform was pretty unlikely and actually may have been a red herring. The surface area for the pressure to act on is so much smaller than the outer can that such a collapse would not occur.

But, unkl300d, I think, did not have the can to look at anymore so we do not have any conclusive answer, just a vague recollection that there was no center grommet. The next time the phenomena gets reported we know what to look for. Sounds like some visual inspections are appropriate before installing these filters, although I have to admit I have never really looked at them hard in the past.

Glad to be of help, TXBill and Miles81_240d, Jim