Old engine archaeology and a busted bolt

[film842]

I feel like an archaeologist on a dig somewhere scratching through levels to find all sorts of surprises. I've got my AQ131A on an engine stand with most of the components off for a cleanup and reassemble.

Today I got the heat exchanger on the bench and pulled it apart even though I didn't think it really needed it. How wrong I was. I found a big lump of seawood/stuff stuck into one of the ports of the inner element. Got it out.

However, as I was originally opening up the case I broke off one of the bolts. Damn. With this case being aluminum (I assume) how do I get that piece of bolt out? Is it the same process as one would use on say, a bolt into cast iron?

Any advice appreciated.

 

[dennis461]

Re: Old engine archaeology and a busted bolt

Problem with that is the bolt is so much harder than the case. Any attempts with drill bits will result in wandering and destruction of the aluminum.

What you need is machinist type handy man.

You'll need a steel template with a hole in it the size of the bolt shank ( Smaller than the bolt diameter)
. The template gets positioned with the hole directly over the bolt.
Next you need a hard end-mill (not a drill bit.) to fit.

Now a strong slow speed drill.

You then use the end mill to bore a hole straight down the center of the bolt.

got it so far?

 

[jerryjerry05]

Re: Old engine archaeology and a busted bolt

ANY???? Of the bolt left above the edge?
I use WD or PB blaster.and a small propane torch and a small hammer.
Spray,heat and tap with the hammer.
Then repeat the process.The spray will work it's way inside and loosen the corrosion as you heat it up.
The tapping will help in the process.
If you can smooth the top of the screw and center punch it.
Then a small drill bit,slowly drill it out then go 1 size bigger,drill again and then use an easy out.

 

[film842]

Re: Old engine archaeology and a busted bolt

Problem with that is the bolt is so much harder than the case. Any attempts with drill bits will result in wandering and destruction of the aluminum.

What you need is machinist type handy man.

You'll need a steel template with a hole in it the size of the bolt shank ( Smaller than the bolt diameter)
. The template gets positioned with the hole directly over the bolt.
Next you need a hard end-mill (not a drill bit.) to fit.

Now a strong slow speed drill.

You then use the end mill to bore a hole straight down the center of the bolt.

got it so far?

Not quite following you concerning the "hard end-mill to fit". Should this end-mill be the same diameter as the hole in template? Am I trying to drill out most of the bolt or simply a small hole right down the middle?

 

[dennis461]

Re: Old engine archaeology and a busted bolt

Not quite following you concerning the "hard end-mill to fit". Should this end-mill be the same diameter as the hole in template? Am I trying to drill out most of the bolt or simply a small hole right down the middle?

The end mill has to be hard, not cheap chinese metal soft.
The end mill has to be the same diametor as the MINOR DIAMETER of the bolt.
The hole in your guide must match the end mill.

Your goal is to remove the MINOR DIAMETER material.
Leaving the steel bolt threads only in the aluminum threaded portion of the casting.
A delicate task.
You then pick out what is left of the threads with a dental tool.

See link for simple drawing.

http://www.parktool.com/uploads/images/blog/repair_help/thread.gif

This process WILL work if you pay attention to detail.
I managed to repair my aluminum cylinder head when I snapped off a bolt in it.

If there is enough broken bolt left above the casting..you could grind tthe bolt FLAT, center punch and use a drill. But if you slip once with the handheld drill and no guide, you'll be worse off.

Option B would be to use lots of gasket sealer in the broken bolt area and see if it leaks. You may not have to do anything with the broken bolt, but thats the closed cooling high pressure water.

 

[film842]

Re: Old engine archaeology and a busted bolt

The end mill has to be hard, not cheap chinese metal soft.
The end mill has to be the same diametor as the MINOR DIAMETER of the bolt.
The hole in your guide must match the end mill.

Your goal is to remove the MINOR DIAMETER material.
Leaving the steel bolt threads only in the aluminum threaded portion of the casting.
A delicate task.
You then pick out what is left of the threads with a dental tool.

See link for simple drawing.

http://www.parktool.com/uploads/images/blog/repair_help/thread.gif

This process WILL work if you pay attention to detail.
I managed to repair my aluminum cylinder head when I snapped off a bolt in it.

If there is enough broken bolt left above the casting..you could grind tthe bolt FLAT, center punch and use a drill. But if you slip once with the handheld drill and no guide, you'll be worse off.

Option B would be to use lots of gasket sealer in the broken bolt area and see if it leaks. You may not have to do anything with the broken bolt, but thats the closed cooling high pressure water.

Thanks for the explanation. I've got it now. I'll post the results.

 

[Walt T]

Re: Old engine archaeology and a busted bolt

You can try Electrical Discharge Machining. A lot of machine shops offer bolt removal services from components.

Homemade EDM removing a broken tap Part 1 - YouTube

If you decide to drill as suggested above, buy a left hand drill set and use those. Be patient and don't break the drill bit off inside the bolt.