This thread on a neighboring site answers the question. I've been frustrated by the fact that all the metal caps I've tried leak....now I know why.

Steel oil cap dissection - Mercedes-Benz Forum

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

I bought a new seal for the SD. It was the wrong size but I had already removed the old one. I turned the old seal and reinstalled. It isn't leaking but doesn't have many miles on it. Just lucky based on the pics in the link.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

crazy.

ok stretch... start taking them to bits and find a way to fix them up!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Interesting! My 85 came with a plastic oil cap which leaks. I also have a shiny chrome plated metal oil cap that looks very different than an OE metal oil cap, not sure if Mercedes made it or aftermarket and it also leaks. I replaced it with a used OE metal oil cap that I got from a used 617 engine and it's the only oil cap I have that does not leak.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

One option is to simply replace the seal with the "blue one" which normally goes on the gas cap. It's a little pricey, and assuming no inherent damage to the cap, your oil filler cap should be good for another 10-20 years without worries.

Is this the 710 cap?

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Gone to the dark side

- Jeff

I second what greazzer has said.

The replacement seal is also the same seal used for the fuel cap, the new seal will be blue (blue tec). It's genuine Mercedes and it solved my oil cap leaking issue.

Part Number: 1404710079
$15.25 @ PeachParts + shipping
up to $17.50 elsewhere with shipping

Junk plastic cap new is $5.0 then another $5 in 2-3 years because the first plastic one broke. Save your self the hassle and get a nice blue seal for the nice solid metal cap.

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Nosce Te Ipsum "Know thyself"

I think you're missing the fundamental issue raised by the guy that posted the images of the dissected oil cap - there is another seal that is between the cover piece and the inner piece. That seal is not accessible, at least without uncrimping the metal cover and separating the two meta pieces, and when it dries out and cracks, allows oil to leak between the inner and outer metal pieces. All the blue, green, black or pink seals in the world won't correct that problem. Now clearly if your outer seal is worn, cracked or missing a replacement seal will cure the problem. If the inner seal is the problem...well that's a different story.

I'm wondering if it would be possible to drill a hole and inject some appropriate sealant between the two prieces to cure the internal leaking problem and allow continued use of the metal caps. I, like most, do not care for the plastic replacement caps available. I've got and extra cap and may do some experimenting....

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Nope. This is on a Mercedes. They use "730" caps.

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― Brian P. Cleary, You Oughta Know By Now

Hmm, 20 more = better! Clever Germans.

Aluminum head engines all use the plastic caps, don't look nearly as classic as the metal ones on that nice rounded 61x cam cover!

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Gone to the dark side

- Jeff

My mechanic's recommendation is to keep them facing down when removed. This way, the oil won't flow "inside" - assuming the internal seal is intact, this makes sense. Most likely, the "OEL" caps are old and the internal seal is similar to what is shown - hard as rock and probably leaking too.

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http://farm8.staticflickr.com/7271/7...144c3fc1dc.jpg

This has been very informative for me. A few months ago, I replaced the seal with one from a fuel cap and it has been leaking like crazy since (actually worse than prior to replacing the seal). I would like to do some testing as well, but I may end up getting a plastic cap in the meantime.

Dkr.

Never thought of the upside down cap factor, ... I'll start leaving mine un-flipped when I change oil, there's always a small oil moat in the channel around the cap when I change oil.

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Gone to the dark side

- Jeff

I just bought a new metal cap on eBay Germany. Seller claims it was recently built and not new old stock.

Neu Orig Öldeckel Aus Metall W107 W108 W110 W111 W114 W115 W116 W123 Mercedes | eBay

Anyone know why these appear to be unobtanium here?

Dkr.

I read in another thread or two not to turn the cap up side down.
I usually place a rag on the radiator support and set the cap on it,
then wipe it out and the VC before replacing it.

Once in a while I set it in a pan of gas to clean it out, air dry it and
so far it doesn`t seem to leak.
I have replaced the rubber seal.

There is this later style metal fuel cap that probably will work on the VC.
Though sort of ugly compared to the original one.





I found this cool looking cap on e-bay
It`s listed as being for a 230S

Classic Mini Stainless Steel Vented Fuel Tank Cap Gas Cap Non Locking | eBay

This is the other style fuel cap

• 
  
• 
  

The fuel caps will work on the VC.
If you use the original metal fuel cap that looks like the 710 or 730 cap
it will sit at an angle, not in line with the cover.

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works