What seals this fitting? If anything at all...

[BOOB]

While performing an oil change, I was just starting to thread the filter canister  bolt into the main body when I noticed the oil pressure gauge’s feed line was wiggling a bit. The oil line fastens to a fitting on top of the oil filter housing that protrudes through the body and provides the female threads for the filter canister bolt. The fitting was loose in the body. I removed the oil line and unscrewed the fitting to discover that nothing was there to seal it. Ive studied a few parts diagrams and none list any type of seal (copper washer, o-ring, etc). The fitting doesn’t seem to have its own sealing bevel under the head, but it does have a groove like it would accept an o-ring. Does anyone know how this fitting seals to the housing?

It’s #36 in the attached diagram

[Charles 230SL]

Boob, I took a snapshot of the fitting on my 230SL and it appears to have an aluminum washer under it - but that doesn't necessarily mean its correct.

[Benz Dr.]

Boob, I took a snapshot of the fitting on my 230SL and it appears to have an aluminum washer under it - but that doesn't necessarily mean its correct.

It is though. Aluminium seal - tighten the fitting down well because there's at least 100 PSI available at times when the engine is cold. Very easy to have seeping leaks if not tight.

[114015]

Bob,
I am sorry to say so, Dan, but there is definitely no seal. No aluminum seal, nothing.

I could tell you a long story about this now and loosing lots of dripping oil,
but I am sure you don't wanna read that.

Fact is there is no seal at all.

This fitting, called A180 184 0117, has a very tight fit and a very sharp thread towards the cannister cover which is attached to the engine block.
It must have this because this fitting has got three threads.
The first for the oil pressure line, the second middle one for its own in order to fit into the cannister cover and the third (female) in the lower part - inside - for the long bolt of the oil filter cannister.

Now, if you do on average  2 - 3 oil changes per year (in the old days) and that over 25 years that makes 50 - 75 oil changes in the regular life expectation of the car/oil filter cannister.
With these often changes the fitting must not get loose at all and that is why its own fit is very very tight in the cannister's cover.
If this thread is loose - and yours is - then the best is to buy the part new (about $$ 38.00 or so). 
You will see that the fit will be much tighter. If you don't want to spend that money go and get your fitting sealed in - best with Loctite or something similar.

Remember, this fit must be very tight because of the reasons Dan and I mentioned.
If you "overtighten" your long bolt for the cannister below, you automatically put pressure to "unscrew" or untighten the fitting. That's why this fit is so important.
And an additional aluminum ring WILL NOT SEAL - trust me!
There is NO SEAL from the factory - clearly not!
 

Ask me how I know .....


IMHO: get a new fitting or glue it in!

Good luck,
Achim

[wwheeler]

Seems like I read in the manual that this is a non serviceable part. In other words, you are not supposed to take it out as part of normal service. Because it contains the threads for the bowl bolt, it must never come loose. I believe when I took this out when I restored my oil filter housing assembly and plate the hardware, I used Permatex #2 to seal and lock the threads. I did not use a sealing ring and have never had any leaks doing it this way.

Haynes says "Do not unscrew upper bolt which is sealed into position". I read a similar thing in the BBB. The seal ring may not hurt, but I would also use a removable thread lock like Permatex #2.

Note: - I just read Achim's message - so don't use the seal ring.

[66andBlue]

No seal ring!
BOOB, if you take a look at Fig. 18-1/1 in the workshop manual (also called BBB = Big Blue Book here) you'll see in the cross-section that there is no seal ring or washer between the threaded union (#8) and the housing as Achim typed already.

[BOOB]

Thank you for the replies! I’ll be sure to not use a sealing ring. I like the idea of permatex #2 (one of my favorites in the shop) or possibly a healthy dose of loctite. A great point was made that over the years of use, many oil changes will occur and the fitting will be put under stress at risk of loosening. I’m leaning towards the loctite for this reason.

Would anyone be able to suggest a torque spec for this fitting? Or should I just go by feel? I understand that it’s essentially constructed like a weak banjo bolt, and  steel vs. aluminum threads so I’ll have to be careful.

[Benz Dr.]

Bob,
I am sorry to say so, Dan, but there is definitely no seal. No aluminum seal, nothing.

I could tell you a long story about this now and loosing lots of dripping oil,
but I am sure you don't wanna read that.

Fact is there is no seal at all.

This fitting, called A180 184 0117, has a very tight fit and a very sharp thread towards the cannister cover which is attached to the engine block.
It must have this because this fitting has got three threads.
The first for the oil pressure line, the second middle one for its own in order to fit into the cannister cover and the third (female) in the lower part - inside - for the long bolt of the oil filter cannister.

Now, if you do on average  2 - 3 oil changes per year (in the old days) and that over 25 years that makes 50 - 75 oil changes in the regular life expectation of the car/oil filter cannister.
With these often changes the fitting must not get loose at all and that is why its own fit is very very tight in the cannister's cover.
If this thread is loose - and yours is - then the best is to buy the part new (about $$ 38.00 or so). 
You will see that the fit will be much tighter. If you don't want to spend that money go and get your fitting sealed in - best with Loctite or something similar.

Remember, this fit must be very tight because of the reasons Dan and I mentioned.
If you "overtighten" your long bolt for the cannister below, you automatically put pressure to "unscrew" or untighten the fitting. That's why this fit is so important.
And an additional aluminum ring WILL NOT SEAL - trust me!
There is NO SEAL from the factory - clearly not!
 

Ask me how I know .....


IMHO: get a new fitting or glue it in!

Good luck,
Achim

So I looked in my dealer's part book and sure enough you have that right. Everything else gets a seal except that part. 

[Charles 230SL]

Hey guys, you know you’re getting old when you can’t even remember doing work on your own car.  I found this string dated Mar 2016; that’s an aluminum washer alright, and I was the one who put it there! (this is embarrassing!)

https://www.sl113.org/forums/index.php?topic=24032.msg172267#msg172267

[BOOB]

Don’t sweat it Charles, I was tempted to add one myself before I decided I should confirm with the experts first. What’s funny is that your explanation of the problem is almost exactly like mine! I’m surprised I couldn’t find your thread when I searched for similar issues.

[wwheeler]

I am just as guilty of a bad memory. I was on that string and recommended PC7 epoxy instead of what I remembered today which was Permatex #2!

Either could work and the point is to lock the threads with something. I do remember finding residue of some sort of a sealer that Mercedes used. No telling what that was 50 years ago.