Broken Cam Bearing Bolt - What now ???

:cry:

Even when doing things by the book, it seems that there is no end to my suffering.

When torquing the bolts for final cam assembly on my xj550, one snapped before reaching the specified torque setting. I now have a broken 1/2" long grade 4 bolt thread I can't access or remove stuck in the head.

Any thoughts from the experts out there ? I'm at my wits end with the problems I've had so far on what was to be a routine rebuild.

I can post a pic if it helps.

 

Pics please ! to help us understand your particular problem better.

 

you know the answer, just take it to a machine shop
that ain't no place to try home brew methods

 

Polock the Sage.

 

Here is the pic. Its the bearing between the number 1 and 2 cylinder for the intake cam, bottom right location in the pic.

 

+1.

This probably isn't a job for your Craftsman EZ-Out set.

 

4nik8r

A couple of thoughts:

Now that the torque forces are off the fastener, it may “easily” come out.

1). Can you get a Dremel cut-off wheel [reinforced type] in there to cut a slot in the top of the bolt shaft? A slot screw driver might remove it then.

2). Can you catch the edge of the bolt shaft with a punch, chisel, etc.? You may be able to spin it out with a tap of a hammer on the chisel.

Both these techniques have worked for me in similar circumstances. If neither of these things work, a Dremel tool with a 1/8” carbide ball cutter might let you bore enough into the bolt shaft to engage an easy out.

 

all good ideas Frankenbike,

I believe one of the reasons the bolt snapped is that the bolt started bottoming out before reaching the 14.7 ft-lbs called for by the manual. So its in there good and tight, and is deep (1/2 to 3/4" threaded in, less than 1/8" sticking up in the journal seat).

1. This would work if and only if I cut through the aluminum casting as well. The bolt end is below the mating surface of the head and cam bearing. The journal diameter is too small to get any wheel in there.

2. Tried this already without any luck

The 1/8" carbide ball cutter might be small enough - I think the bolt diameter is about 5mm or about 1/5". I'd have to see what's available. My fear is that I'll only do more damage, but a machine shop will charge me $60 or more, if they can even get it out without damaging the aluminum.

 

4nik8r,

A machinist at my work had told me that cooling the bolt + surrounding aluminum, [maybe dry ice] and then heating the aluminum might help loosen it’s grip. Aluminum will expand faster than the steel will, is the theory.

I’m in a similar boat with broken-off intake manifold bolts in my cylinder heads. The problem is compounded because they were apparently rusted in too. I may just have to yank the head off & take it to the machinist.

Will be trying the cool/heat thing soon.

So Suck.

 

Please take it to a machine shop! You need to get this issue off your mind so you can get on with the rebuild. No matter how much thought you put into this it is time to bite the bullet and take it to the pros. It will likely be the best $60 you will ever spend.

One other thought. If the bolt bottomed out in the hole and stopped turning then the torque wrench should have let you know the torque value had been reached. The torque wrench doesn't know whether the bolt bottoms out or the torque value has been reached by the normal compression between the fastener and the part.

Is it possible that you missed the cue when the torque wrench "snapped over" once the 14.7 ft/lbs was reached? If so, then this illustrates why I was very uncomfortable with my Harbor Freight torque wrench. On the low end of the scale I couldn't discern the snapping over of the wrench. It could have been specific to the tool I bought from HF.

This whole thing just makes me sick. You have put so much time into your project. Believe me once you get over this hurdle get the thing together and climb aboard you will look back on your trials as just what you had to do to get it going. They are a freakin' blast to ride!

Best of luck to you.

 

Thanks for all the advice. I have already gone through what frankenbike has with a broken exhaust stud. That already cost me $65 at the welder's to get that out. If fact, that was one of the things I wanted fixed (along with oil leaks and other minor issues) that lead me down this path of no return to a rebuild. (Bike has just over 61,000 km, bought it in '87 with 4,600 km on it, have had some tuning issues and figured this winter was the time to tear it down, have a look, do valve shims, valves, de-carbon, re-gasket, etc. Overall, things are in really good shape).

I agree with the bottom out theory, the irony is I got every other bolt to torque properly at that setting and even did the torquing in 3 stages: 7 ft-lbs, 12 ft-lbs then 14.7 ft-lbs. Always I heard and felt the click right up until the very last bolt. Only once it snapped (on the very last bolt, of course) did I notice that by taking the bearing cap off and hand tightening a bolt into the other hole to bottom-out did that bolt height look to be about the same as the combined height of the two pieces of the broken bolt. The softer aluminum has some give such that the bottoming out isn't an immediate "lock", but if it is not bottomed out then its very close. Either way, its in there good.

I have a brass fitting from an old air valve that has an inside diameter a little smaller than the outside thread diameter of the bolt, and it has an outside diameter just small enough to fit into the journal, and it tapers up to a hex end. I was thinking of trying the following:

1. Torch heat the end of the brass fitting until it expands as much as possible;
2. Quickly hammer the fitting over the 1/8" exposed broken bolt inside the journal;
3. Let the brass cool to room temperature;
4. Torch heat the aluminum near the threaded recess
5. Use a wrench on the hex end of the brass to spin her out

What do you all think ? If the brass is too soft to grab maybe I'll use flux on the bolt threads and plumbers solder inside the fitting fed from the open hex end

If brass doesn't do it, maybe I'll try to find some other thick walled steel tubing of the proper inside and outside diameter and try that...

If none of this works, agreed its $$$ time.