Valve cover help -broken thread on the inside

So I installed a new valve cover gasket the other day, and when I pulled the cover off I saw that the threading for where the bolt goes was totally busted off (one of the middle 4 bolts threading). How can I fix this? it's leaking oil since the bolt basically screws into nothing.

 

Best bet is a Helicoil.

 

Helicoil - Go to any autoparts store. On my bike that is a M6 1.0 pitch. Verify your hole size first. Costs about $30 for the kit. you drill out the hole - tap with the included tap and thread a "spring" in that becomes the new thread. Works great. I had to do one of mine. Kit will have about 10 or so of the "springs".

Only other option is drill out the threaded insert and replace it. Bigger pain. The helicoil is easy. Cover your work are to not get shavings into your engine of course.

 

I don't think that the Helicoil will work, because I can't drill anything out. The threaded metal where the bolt goes actually busted off. So the threads on the bolt are only touching half of what it should. Instead of being a circle like it should, it's more of a half moon, because the other half busted off. So the helicoil might possibly work, but I'm thinking i would have to jb weld it to the remaining threads. What are you thoughts?

 

Maybe a picture would help. My valve cover threads are in some pretty thick metal. If you have the part that busted off you may be able to JB weld it back and helicoil or tap it. Another option you can try is to rebuild the area with JB weld then just drill and tap. I'm not sure how well that would work -depends on how well the JB weld sticks to the area.

 

What bike is this for? Is this the cam bearing surface??? If it's not the cam bearing surface and for the seca 550 or fj/fz 600 engine than I will have an extra spare. It might be the same part for the other XJ models but I am not sure. If it's the cam bearing surface then your best bet would be take it to a machine shop and have them weld up the area then drill and tap it and remachine so it will fit. Not cheap but better than pulling an engine. If all else fails get another head. Again not the desired way to go since it's alot of manual labor and expense. The cam bearing surfaces were machined as a set and only go one way. Every head is different since it is essentially impossible to locate a head in exactly the same way and line bore the bearing surfaces. I have repaired one on my seca 550 but wound up making a bushing since I noticed that the threaded area was stripped but not enough material to drill out larger and put a helicoil on it. I pressed the bushing on the outside of the threads and rethreaded the cam cap. I never had that strip or worried about it after it was helicoiled.

Sean

 

Do you have the part that broke off??? Is it laying in the bottom of the head or did it go down in the motor???

 

jb weld bad idea. It is better to do what dinoracer said. A picture would help if you still have the bolt hole then heli coil will work. But are you trying to say that the bolt hole actually split off??

 

Yeah, a picture would be helpful, but I'm not planning on delving into this until winter. Yes nsosh, the bolt hole actually split off. I haven't seen any pieces of metal laying in there, but the bike has leaked a little oil since I bought it. Maybe the PO? Not sure, but kinda in a bind.
My brother is a CNC machinist, so that sounds like an option. Weld a piece of metal in there and then drill it out and use the heli coil.
What do you guys think?

 

Good Plan, Maybe pull the head to do a better job

 

Welding in material is definitely superior trying a JB weld fix and the way to go since you have access to the right tools.

The problem with the JB weld idea (as I mentioned before) is how well it would bond to the surface. I have had a lot of success with it but also some real failures.

 

If you have the option to pull the head and weld it up, machine and then redrill and tap that would be 100% the best way to go. I would be very concerned as to where the "piece" went too. I would pull the sump and see if the piece got all the way through, and look down the camchain gallery REAL CAREFULLY with a flashlight when (if) you have the head off. It would help if we knew exactly what bike you're working on.

 

Umm why does he have to pull the head if its the cam cap. Check my gallery soon to see what I did to repair one of mine. It started to crack and I put a bushing around it. Might take a day or two to get approved from the mods.

Sean

 

Hey, I'm riding a 82 maxim 550. I appreciate your guy's help on this