Cracked Cam?

[paperplane94]

I have posted on bimmerforums as well.


First of All its an m20.

I was going about replacing the camshaft seal and when I took off the cam sprocket, the alignment hole had been chipped off, either by me or some other mechanic but most probably me.

It is my understanding that this is the end of the camshaft that broke off so will this effect its balance or screw something up or do I not have to buy a new camshaft?







Here is the piece

[jlevie]

That is very worrisome. There may not be enough bearing surface left for the dowel to ensure cam timing. If the cam and sprocket get out of time bad (and expensive) things are going to happen. I would not run an engine with that fault. I'd say it is time to pull the head and replace the cam.

From the picture I'd say that this is an old failure. If it was recent the fracture area would be bright.

[paperplane94]

You are definitely right about it being an old failure.

Now that I looked more carefully you can see how the chipped piece was placed back on with the sprocket last time the head was changed.

The chipped piece has been rubbing along the inner surface of the cam sprocket next to the alignment pin.



Yeah its an old failure, but it HAS been holding since the head R&R in 2005/approx. 40k miles ago so whats the problem with putting it back on with some J-B Weld or the like. I do not have a fund for buying new camshafts!

I am just a starvin student.

So what is the best REPAIR that I can do without having to pull the head and installing a new camshaft?

[Sagaris]

I don't care how tacky it is, I could see myself fixing it with JB, saving up for a spare head, building the head up and bolting it on at a later date when its more convenient.

[jlevie]

I think the only thing you could do, short of pulling the head and replacing the cam, would be to JB weld the chip back in and hope that the cam doesn't jump time. Understand that if it does, at the very least you will have bent valves. At the worst, broken rockers, bent valves, a destroyed head, and destroyed pistons.

[paperplane94]

I understand the risks.
If it does happen after the JB weld it will be my excuse for a new engine on this slow e34 slushbox!

But I will definitely make a note in the service sheets. If it does break I will post again with a damage report.

Hopefully it wont happen the moment that I start it after finishing the seal/timing belt job.
:ohsnap:

Thanks for the advice guys. Still no replies @ BimmerForums.C!

[scottinAZ]

I would think you would be OK with jb welding it in place. Most (if not all) of the force on that area is radially in rotation with the camshaft. you also have a ridge in the face of the pulley that will assist in keeping the piece in place.

You also have about 40K in useage on the part without the knowledge it is broken. Piece it together, start saving for a reman head and a Schrick cam to go into it


(all that said, it would bother the shit outta me knowing it is busted, and I would replace it at the earliest opportunity, YMMV)

[matt0300]

I have an extra can if u need one

[bloodshot-e30]

i has a cam if u want

[Wanganstyle]

yes sombody will dontate u a cam due to scary factor, Miata had a similar failure with the crankshaft + woodruff key, not a good failure. Nissan has similar wear issue with RB26det and oil pump, if you are mechanically able please replace it for your own sake.

[hotballs]

I had a cam with a crack and same failure. JB weld it back into place. In the long run you would want to get a new cam or weld something up. I honestly bet it will be fine. Depends on how often you're taking up to the limiter.

[paperplane94]

Off to WallyWorld in the morrow to pick up some JB Weld. I dont think this DD will be seeing alot of redline.

I should ask the mechanic who broke it to buy me a new camshaft, but he will be in denial for sure and thats too much of a hassle.

Thank you guys for the advice! Way better to ask/look here than at the e34subsection at bf.c since they all have M50's, whatever.

[paperplane94]

BTW What is the camshaft made of exactly? I just want to see that my other options are for metallic adhesives.

[Ryann]

In my opinion your cam timing is in no danger at all. With the way the cam gear fits over the end of the cam you'd have to shear the pin completely off before you had issues. Also, there's much more than half the circumference left of the hole, most of which is at full depth.

[scottinAZ]

BTW What is the camshaft made of exactly? I just want to see that my other options are for metallic adhesives.

cast iron most likely, what exact alloy, I couldnt tell you