Need advice to remove broken exhaust bolt

[TurboTravis]

Originally Posted by andyd
You are almost there. 5/16 =7.9mm. Run a 9/32 bit in and then use a pick to pull the rest of the bolt away from the threads. Use a fresh bolt or a tap to chase. The thread doesn't need to be perfect to accept a bolt


Totally agree. Why would anyone do anything different in this case?

 

[Linctex]

Originally Posted by andyd
Run a 9/32 bit in and then use a pick to pull the rest of the bolt away from the threads.


YES!

 

[i6pwr]

I'm with you on drilling to 9/32, I figured to at least stop here and ask first before I removed the welding option.

My buddy is worried the arc will blow through the thin bolt the way it is. We tested a few scrap pieces, the aluminum block dissipated the heat fine, no melting, but that was a complete bolt, not a hollow tube.

 

[DoubleWasp]

Originally Posted by atikovi
Heli-Coil is 60's technology. Use something like www.timesert.com Stay away from EZ outs. 9 times out of 10 they will break in the hole and then you are really screwed. If you need an extractor, get a set of Rennsteig like

Nuts and bolts are even older technology.

Recommendation was made given a situational assessment:

1. Expediency preferred
2. Common local resources best option
3. Non-critical low-stress fastener

Heli-Coil and the like can be yanked right off the shelf at most auto parts stores. Beats running around for or waiting for Time-Serts to come in. Also isn't going to make a difference in the world for an exhaust bolt. Walk in the park for Heli-Coil or equivalent.

 

[atikovi]

Convenience in getting a replacement part would be last thing on my mind after spending hours wrestling the remains of the bolt out. I would want the best fix available even if it took a few days to order and cost a few dollars more. But that's just me.

 

[DoubleWasp]

For an exhaust bolt, you're getting absolutely nothing more in return for waiting on a Time-Sert than you are doing a Heli-Coil. Nothing.

If we we're talking something where a difference could actually be found like a main cap, cylinder head, etc., then you are 100% right. But if one Heli-Coils an exhaust manifold mounting bolt/stud hole, that bolt or stud is going right in, and that hole is never going to become a failure point. Ever.

 

[i6pwr]

I appreciate the rapid-fire responses...one reason I enjoy this site...

After debating the remedy with my neighbor about welding a nut, we took the advice of finishing the drilling of the bolt then try to tap the threads again.

This choice gave us the lesser chance of digging a deeper hole...(no pun intended). There just wasn't enough meat left on the bolt and if I had to drill again through the weld that would have proven even more difficult given the location of the bolt. One big concern was the remnants of the bolt breaking off in the hole if we did manage to get a nut welded, and possibly damaging the existing aluminum threads with the hot arc due to the thin wall remaining of the bolt.

I had about 18MM of usable thread on the factory bolt, I managed to get a good 11-12MM of usable thread after drilling and tapping.

I went down in size on the drill to 17/64 to avoid damaging the existing threads, and didnt go too deep to stay away from the water jacket.

The Heli-Coil was an option, but I wasn't able to find the longer length inserts.

Again, I greatly appreciate all the input, helped me a lot in the time constraint I was faced with.

Threads turned out good, the 2nd and 3rd thread is good, just reflection of flash.

 

[FlyNavyP3]

Glad it worked out! Drilling and tapping is a good option, had you mangled the threads trying to weld you would have been bummed you didn't just drill and tap.