Cam cover bolt threaded hole repair

I was working on my "old red" project again after several months. Years ago when I was trying re assemble my bikes top end between home improvement projects I used a bolt that was 5 mm too long that broke off when it bottomed out in the head.

After putting it together last fall and running up the road and back as a test ride it was leaking worse than the original leak which cause me to put old red on the shelf 12 years ago when I originally tore it apart. Today armed with an top end gasket set I have sworn to fixed the bodger's to fix this cam cover bolt hole. I need to fill in the hole that I created from trying to put a helicoil to allow me to half assedly install the cam cover before.

I feel I have 2 options, an epoxy filler like lab metal high temp or alumiweld aluminum brazing rod. I think the brazing rod will be a better solution but I am concerned about melting the paint on the head and creating a bigger mess. Any suggestions?

Please be gentle, I know I did a shitty job on my original repair, now I have the engine apart and want to make it oil tight once and for all.

You need to get the original bolt out first. I would grind it flush, put the valve cover on and use it as a guide with a drill bit fitting the hole in the cover. I'd drill just enough to have a starter hole in the top of the bolt if it's centered. Then I'd use a drill for the helicoil to drill until it bottoms. You might be able to pick the steel threads out. At that point I would have the hole fill in welded. I'd grind it flush and use the valve cover to make another starter hole, drill, tap and install a Heli Coil.
Steve
BTW, you'll want to have the cam cover bolts in so the cover will be in the right position.

Not as bad as you might think. I see the head is off the engine - I am correct on this?

If so - do yourself a big favor and take it, and the valve cover, to a machine shop and have them repair it on a milling machine. Bring the head to a few shops and get some quotes. Likely it will only cost about $50; money well spent!

It is very difficult to drill the steel bolt out of the aluminum head without having a twist drill wander off and into the aluminum, as you have already found out. On a milling machine, they will use an end mill to precisely remove the old bolt without further damage to the head. Then the hole can be drilled and tapped for a thread insert, which will be stronger and more permanent than an epoxy filler (like JB weld) could ever be...

Find a local shop who does MDM machining,it's like an arc weld,but destroys stuck bolts like what you've got.

What Kray-Z said.

It's worth the few extra £ to get it right. I've had the same issue over the years and ended up wasting hours and hours with worse results. Unless you have the correct tools IMO you'll just make more of a mess

I got the remains of the bolt out this evening.

I will call around tomorrow about getting the hole filled and the head decked out on top so that the cam cover gets tight.

Would it be worthwhile getting the jugs decked on top to help sealing the head? Should I be having any thing else done while I am at it?

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Check it with a straightedge and a feeler gauge.
Steve

I want to make this thing oil tight once and for all.

Any tips to make sure it is completely oil tight? Also, what is the secret to getting the old gasket off between the crankcase and the jugs?

I stopped in my local machine shop at lunch today and they said they don't tig aluminum. They suggested drilling another hole deep and threading that hole, I am dubious about that.

They did suggest a guy who may be able to fill in the hole who does this type of thing.

I had found in another forum where someone had suggested filling the hole with aluminum self-fluxing brazing. Does anyone have any experience with that.

Bad idea. Doing that can deform the casting. Get someone that does aluminum Tig welding. He will more than likely know what to do next.
Steve

Hey, how bad is the damage? I would install a thread repair insert, like a time-sert or similar (not a heli-coil - its too late for that) judging from your initial photos. No welding required, but it should be done by a competent machine shop. Most automotive and industrial machine shops deal with broken bolt removal and repair on a regular basis - try to find one of those that has a vertical milling machine in their arsenal.

If you must fill with TIG weld, you'll need to machine the gasket surface flat afterward (you might get away with carefully filing it down), and probably need to use RTV sealant on the gasket in at least two places because the weld will invariably leave a tiny depression or channel in the surface where the weld puddle meets the original surface.

Don't bother with a filler epoxy or brazing in a filler in this situation - waste of time, money and effort IMHO. Go the full 50 yards and do it right the first time.

Only have the cylinder block top machined (surfaced) if it is warped or otherwise damaged. Do the usual checks with a straight edge and feeler gauges as per the factory service manual. If it passes - leave it be. Check the head surface, too. The head gasket mating surfaces should only be machined flat on a large machine designed specifically for this purpose - usually found at automotive machine shops only.

I have gotten the hole filled up and am going to take the head to the machine shop to get the excess weld planed flat so that I it can seal the gasket.

In the course of taking it apart, I noticed that the chain guides need replaced and pulled the jugs so I could pull the rear cam guide. Here is the quandary that I have been contemplating while waiting for funds to recoup from the first of the month. Do I take the jugs to the machine shop also so that they can be honed and/or checked out for being spec and install new rings? Do the former and forgo the latter? forgo both?

This is not going to be ridden a lot once it running perhaps 1 week for a short commute, I want something that doesn't smoke or take oil, and that doesn't leak but I am not going to be racing it anywhere. More or less a cruiser bike to go on evening jaunts and to commute occasionally, so I am looking for reliability.

The engine has 28K miles on it. It ran well 12 years ago when I tore it apart to fix the leading oil rings. I am not wanting to take it apart again. I humbly request your feed back.