Oil leaking from plug in 380sl block?

[mbboy]

I think I finally found the source of a mysterious oil leak from the engine of my 380sl. I was afraid it was coming from the rear main seal or the head gasket, because oil was dripping from the bottom of the bell housing just behind the grate. However, I replaced both of those over the winter, and the valve cover is dry.

As it turns out, and as the picture shows, there seems to be some sort of a plug on the rear of the left head -- just below the valve cover and to the left of the large bolt in the center of the head -- that's definitely leaking oil, slowly but surely.

I'm assuming and, hoping, that it's an Allen head with some sort of washer on it that can be replaced. So I was wondering if anyone here has seen this problem, and knows how to fix it.

Thanks in advance for any help anyone can give me.

[meltedpanda]

that is not a freeze plug is it? You are sure it is motor oil?

[mbboy]

No, Panda. Its definitely not a freeze-plug, and definitely oil, not coolant.
After doing some research, I'm tending to think it may either be what MB calls an "oil galley plug" or a plug that MB placed in a casting hole, but
I'm still not sure.

[bergmjh]

That is some sort of oil plug. Try to tighten it first and if that does not fix the problem, remove the plug and there will be a aluminum or copper gasket that you want to replace before replacing the plug. Best of luck John

[meltedpanda]

yes I remember reading now of the casting plug, but thought it was lower, anyhow John has a good plan, just dont overtighten as to strip

[mbboy]

Thanks for the advice, guys. So, I figured I'd just go out and tighten it up, but no such luck.

As it turned out, I couldn't fit an Allen socket and ratchet into the space between the plug and the firewall, and I couldn't get enough force onto a regular Allen wrench to budge the plug.

So now I'm considering just closing the thing off with JB Weld, since people have successfully used it to patch cracked blocks and, AFAIK, the plug has no other purpose other than to seal the hole.

Is there any reason why I shouldn't just seal it off?

Thanks in advance.

[ctaylor738]

Can you slip a piece of pipe, like 1/2" copper, over the hex key to get some more leverage?

[meltedpanda]

probably not , but doubt JB will hold unless you get the area completely clean. Try Chucks idea,, cut the hex wrench so that it just is long enough to go into the hole, then use a levering bar

[abiby]

Originally Posted by meltedpanda

probably not , but doubt JB will hold unless you get the area completely clean. Try Chucks idea,, cut the hex wrench so that it just is long enough to go into the hole, then use a levering bar

...and loosen it before you try tightening.

[DANSMB]

JB Weld will work fine if you warm up the engine a little to help curing and clean the area well with carb or brake cleaner.

Dan

[mbboy]

Thanks again for the advice.

I did manage to get a 6mm hex key in to it last night, and I tightened it until the hex key started bending. I'll take a look at it in the morning, and if it's still leaking, I might try to get a 6mm stubby Allen socket that Snap-On tools shows for about $13.00, as that will probably give me enough room to get the socket in there.

I'll also call the dealer in the morning and see if I can get the washer that's in there without too much trouble, just in case? If not, JB Weld is still an option.

[ctaylor738]

You might want to put some thread sealant on the plug before it goes back in.

[mbboy]

Went to the dealer to order the sealing ring. It only costs a couple of bucks. but they have to get it from Germany. Yikes!