I've been leaking small amounts of oil from my cylinder head cover for awhile now, and yesterday I finally removed the cover and found this:



Not sure how this happened, and as of now, I have yet to locate the piece of metal that broke off!! The retaining bolt can't get any grip and this site is the source of the leak.

any help would be much appreciated.

i cant get the link to work

try here for posting pics ..

https://www.k100-forum.com/t998-posting-pictures-and-movies

Here's another link if the above photo isn't working
http://www.flickr.com/photos/70983501@N06/8449884399/

I would take off the whole engine bottom plate and not just the Oil filter cover to see if the missing metal is in there, with the size and weigh (assuming it came off in one lump and it looks like it did) it should have worked its way down there.

88

Ask experienced machinist. Broken thread isnt much stressed, its just for cylinder head cover, but oil and high temps ask for profesional advice and service

could the piece of metal been retreived by the "po" already ?

possibly you could have the saddle rewelded and tapped to take a bolt again ? as finding a suitiable candidate could be troublesome .

job for a pro i recon .

Thanks for the replies. I'll dig into the engine to hopefully find the missing metal. As for new threads... I know the caps are matched to each section of the case they attach to, but I've also seen posts about people getting replacements from "junked" engines. Any thoughts on this?

Also what about sealing off the hole on the case cover to prevent oil leakage? The only leak is through that hole, so the other bolts must be sufficient to prevent leakage around the rest of the cover. Could an epoxy with a high heat tolerance work?

You have to find heat and oil resistant epoxy. It could work but carrefully with tightening.

The caps are line bored with the head during manufacturing so they become a matched set. Since there is no bearing insert a cap from another head probably would not work. Used heads are cheap. That is how I would proceed. Welding the cap risks distorting it and causing more problems.

What Nino has suggested is about the only way you will have a chance of a repair without removing the head. I would try the Permatex strip epoxy and rough the cap with a burr before you start and clean it with the carb and injector cleaner. I will say it would hold provided you are gentle with the spanner when tightening the bolt.

Themason wrote:The caps are line bored with the head during manufacturing so they become a matched set. Since there is no bearing insert a cap from another head probably would not work. Used heads are cheap. That is how I would proceed. Welding the cap risks distorting it and causing more problems.

I agree, best bet is a used head.

Best regards
JAP

Thanks guys. I'll start with the epoxy fix and see how it holds up. Hopefully it won't come down to changing out the head. I'll check back in soon with an update.

Hi TRIceberg,
I've just taken a bearing cap off my spare engine to see if I could suggest a solution.
The 6mm thread in the cap is about 17mm deep, the thread on the cover bolt is about 13mm long and, from your picture it looks as though the cap is broken at about the 13mm deep mark. Now, if you were to fit a 6mm stud, say about 40mm long into the bearing cap, there might be just enough thread to hold it in place. I'd use either epoxy or Loctite to fix it and then use a nut and washer with the standard rubber seal (and maybe a bit of silicon sealant) to hold the cam cover. A dome nut would make it look pretty.
Could be easier than replacing the head.
Good luck,
Paul.

There was a forum member who had the same problem a few years ago, they put a used one on, I wonder how they made out in the long run. I would try that, particularly if I wasn't going around the world on the thing.

Hi there, following Paul´s idea I guess you could make a saddle with a nut welded to it and hold in place by the cap bolts, as show on the draw




Being steel the nut can hold the stress, keep the original cap centre hole so the original bolt can be used.
Make the saddle legs as long as possible to assure maximum stiffness.
Hope this helps.
Best regards
JAP

great suggestions paul and jap

JAP,
I like that idea.
I suppose it depends on what machining facilities are available, but based on your thoughts, if the top of the cap were to be milled flush, a simple plate between the cap fixing studs with a 6mm tapped hole should work. Just need to get the heights right.
Paul.

Yes Paul thats the idea, grind the cap, flush with the nut base, and the saddle is a bent plate, thickness like a washer or so. The u shape is what gives the required flexural stifness.
Best regards
JAP

Hi guys,
As you know I like a challenge, especially if it means making swarf.
Although my original idea of a 6mm stud would probably work, JAP's idea was more elegant and retains the original elaborate cover bolt, so I had a play this morning.
Firstly I made a note of the significant dimensions.



I then milled a block of alloy to replicate the height of the cover fixing hole, tapped M6.


Fortunately the camshaft bearing cap fixing studs are long enough to accomodate the thickness of the alloy block without having to cut back the bearing cap. (Hmm, I wonder why BMW made them so long?)


Well, that would seem a good way of going about this repair and it still retains that pretty cover fixing bolt.

So, TRIceberg, doing it this way would only mean filing away the broken section of your cap to allow the alloy block to sit squarely on the original fixing faces: and as I don't have a use for this lump of alloy now, if you want it, PM your address to me and I'll post it on to you.
Cheers,
Paul.

Hey, nice job!

I am willing to bet swapping heads would take less time than this process.

This one became a multinational project
Great job Paul
Best regards
JAP

The mason said it may be quicker to replace the head= It might be quicker to order another cap from a wreckers and then machine off the cam tunnell and then clean off the crook cap hat and add the bought one to the existing cap. a similar amount of fun as is being experienced here at present,? maybe?

Excellent job Paul

PM sent

Thanks to everyone for the help. I went from no options to several good possibilities in a matter of days! I'm gonna wait for the piece from paul. I've never seen a thread where someone builds a replacement part for another member (for curiosity's sake btw) and then, having no use for the part, offers it free of charge! Simply amazing. I'll post a picture once I get it set up. Thanks again.