Unusual discover in oil filter housing

[kerry]

I changed the oil in my 79SD today for the second time in my ownership. I glanced down at the tube attached to the oil filter housing lid and noticed something sticking out near the top. Something was jammed in the hole near the top. It was wide outside the tube but tightly jammed in the hole. I don't think it could have gotten into this position coming from the inside of the tube. If I were to guess I'd say someone took a piece of tin foil, folded and twisted it and jammed it into that hole. I was able to remove it with a pair of needle nose pliers but couldn't do a complete forensic analysis because I was changing the oil on the street and it fell to the ground and I couldn't find it.
Anyone have any hypotheses about why someone would do this or how it might happen without deliberate action? What's the purpose of that hole and what are the consequences of plugging it? I've noticed nothing unusual with the oil pressure on the car.

Probably junk caught on the filter during manufacturing/packaging.

That hole is the oil drain back to the pan for the bypass section of the filter. If its plugged then the bypass section wasn't filtering (flowing oil). The flow through it is so small I doubt anyone could detect any change on the pressure gauge or engine operation.

[Palangi]

Maybe a remnant of a foil seal on an oil bottle?

[kerry]

Originally Posted by Palangi

Maybe a remnant of a foil seal on an oil bottle?

That would explain the foil part. Could a remnant make it through the engine from the oil fill hole to the filter housing? Or would someone have been filling the sump through the filter housing?

[compress ignite]

BUT,I don't think it'll push debris through that bypass section.

[compress ignite]

BUT,I don't THINK it'll push debris through that bypass section.

EDIT:
You know what...
I'm more and more tending to look with favor on a centrifugal bypass filter
(Horrendously Expense though)
...nothing gets past them.

[fdanielson]

There is no way for a piece of metal that large to get past the filter. As suggested earlier there is the odd chance that the piece of foil came from the filter itself but if you look at the holes on the inside of the bypass filter section it would be fairly improbable that a piece of metal that large could migrate out.

The most likely scenario is that someone second guessed the Mercedes engineers and plugged the hole. There have been a few threads on oil filters and the oiling system where this has been discussed and at least one person has posted that they plugged that hole.

[kerry]

Originally Posted by fdanielson

The most likely scenario is that someone second guessed the Mercedes engineers and plugged the hole. There have been a few threads on oil filters and the oiling system where this has been discussed and at least one person has posted that they plugged that hole.

That would account for how tight it was pushed into the hole. I don't see how it could get into the hole as tightly as it was without deliberate human effort.

[jt20]

Originally Posted by fdanielson

There is no way for a piece of metal that large to get past the filter. As suggested earlier there is the odd chance that the piece of foil came from the filter itself but if you look at the holes on the inside of the bypass filter section it would be fairly improbable that a piece of metal that large could migrate out.

the two engines of this era that I dismantled with bearing failure had foil-like / flakey bearing shavings in the oil filter canister.

That hole in the post is not that big

[kerry]

Originally Posted by jt20

the two engines of this era that I dismantled with bearing failure had foil-like / flakey bearing shavings in the oil filter canister.

That hole in the post is not that big

Are you sure it was bearing shavings? Could it have been something else? I considered the fact that what I found might be some kind of bearing material but the engine gives no indication of any problems whatsoever.

[Chas H]

My first thought when I read the OP was that a bearing had failed. It's common to find foil like debris in the oil filter and such debris will indeed go right through a filter.
But the swarf in question could have got into the filter can during an oil/filter change.

[jt20]

they were identical. Just smaller than those caught by the pump screen.

An engine with bearing damage is not required to give any indication of damage until it is way too late. (not that I think your 'foil' is babbitt)

[tangofox007]

Originally Posted by Chas H

It's common to find foil like debris in the oil filter and such debris will indeed go right through a filter.

There are plenty of bypass filters that come out of the box full of debris. How often does that debris "go right through" the filter?

[jt20]

it usually sits in the bottom of the housing then the next filter gets put on over it.


It is certainly strange, and even stranger that the oil would be so turbulent inside the filter on the shaft side that it could keep a 'chunk' of metal suspended and lift it into that hole.

[Chas H]

Originally Posted by tangofox007

There are plenty of bypass filters that come out of the box full of debris. How often does that debris "go right through" the filter?

Very often. The foil like pieces are quite sharp and cut right throught the filter medium.
I always inspect filters before fitting. I can't remember the last time I found any debris in a new filter.