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Oil filter unit draining empty

5K views 8 replies 5 participants last post by  DrX 
#1 ·
Is it normal for the engine oil filter unit that is on top of the motor to drain out by itself after an hour. I though an anti drain back valve prevented it from emptying
 
#2 ·
No. It should not drain. Most such issues are caused by damaged or missing o-rings in the filter canister. You do not state the year-model but to my knowledge all MB that use a canister filter have a o-ring under the cap and o-rings on the filter "stem". The large cap o-ring should be changed with the filter and most have a replacement in the package. The small o-rings on the stem can be changed every second or third filter change.
 
#3 ·
Each filter package comes with full set of orings.
I tried to save dirty fingers by doing small orings every 2nd time, but since we change oil with more than a year intervals, I could never remember if I replaced them last time.
Get rubber gloves, a cardboard where you can put filter assembly on and do it every time.
Than on couple of cars I bought used I noticed "extra crispy" filters.
The cars suppose to have recent oil change by selling dealer.
I don't think they cheated on oil change as that would be easy to notice, but nobody can detect skipping filter change with oil change.
 
#7 ·
After an hour i unscrew it fast and pull it out, not a drop of oil anywhere, the filter and housing is completely dry, no drips that should be present if it contained oil. Another reasoning is the oil level goes up 3/4 to a quart after about an hour. If the filter and housing had oil, I would be pulling out a dripping mess. I didn't get even a drip. A 3rd reasoning is the louder chatter I hear for about 3-5 seconds on startup. It sounds like a dry valve train for a bit. My guess is a bad anti drain back valve.
 
#8 ·
When I can understand your concerns, we are talking highly computerized cars and I would tend to believe that with oil pressure coming too slow, you'd have a warning.
Sometimes it comes to trusting or distrusting German engineers.
To make it clear, I am generally distrusting and on wife airmatic I installed a pressure gauge that monitors compressor work.
Sometimes it is that simple.
 
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