Broken bolt

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Been Around the Block
Not really a motorcycle question but i recently broke one of the bolts to my thermostat housing in my truck. I was only able to remove it by drilling it out with bigger hole. My question is how do I go about fixing it? I heard the helicons suck and don't hold. Is there another method?
 
I prefer time-serts over helicoils, but they can be expensive. Are you not able to just tap the hole that you drilled and use a larger diameter bolt??
 
effed up helicoils are mostly due to a poor wobbly oversize job making the helicoil thread with the helicoil tap
as with any tapping a thread the tap must be run in straight and true,if you waller it about it fooks the thread
 
Heli... once test fit for finger tight through the housing without hose to make easier add a nice drop of red locktight to the coil before putting it all back but this time put just a smidge of never seize on the one that got away... so in summary you have glued the heli coil and greased the bolt ;)
 
Tune-A-Fish said:
Heli... once test fit for finger tight through the housing without hose to make easier add a nice drop of red locktight to the coil before putting it all back but this time put just a smidge of never seize on the one that got away... so in summary you have glued the heli coil and greased the bolt ;)
Click to expand...
yepper ;) the "wicking" loctite is handy for this type of app as well
 
This might sound dumb but how do you keep it straight when drilling? I bought the helicoil kit and I'm a wondering how I'm gonna keep this as straight as possible.
 
Tune-A-Fish said:
Heli... once test fit for finger tight through the housing without hose to make easier add a nice drop of red locktight to the coil before putting it all back but this time put just a smidge of never seize on the one that got away... so in summary you have glued the heli coil and greased the bolt ;)
Click to expand...

Is that sentence even a structure? I am pretty sure I can tell what you mean (Put a dab of red Locktite between the Heli-coil and the tapped hole, and a dab of anti-sieze on the bolt), but even for an experienced mechanical person, like myself, I had to read that a few times to figure out what the heck you were saying! And even then, I am only 90% sure....

???
 
Thats why he added, "so in summary you have glued the heli coil and greased the bolt".
 
8ball said:
Is that sentence even a structure? I am pretty sure I can tell what you mean (Put a dab of red Locktite between the Heli-coil and the tapped hole, and a dab of anti-sieze on the bolt), but even for an experienced mechanical person, like myself, I had to read that a few times to figure out what the heck you were saying! And even then, I am only 90% sure....

???
Click to expand...

Yup... some of are slow at writing, but others are reeeealy slow at reading ;)
 
aluminum is not as difficult as cast iron,it is still gonna want to suck-in the drill bit... but cast iron is extremely self feeding
all you can do is eyeball it straight 90 90, and use a lil oil, and brase yourself,try to hold back on the suckage, and use wide open high speed on the drill motor,it should follow the hole nicely... if the tap has a gunpoint it is not neccesary (and better if you don't)to go back and forth motion just keep tapping until you feel some greater resistence then back it out clean threads ,repeat
 
If you really want to get technical and have the ability, you could build a drill jig using the housing as a pattern. Cut a chunk of sheet metal the shape of the the housing and drill it to match use some small tube stock and tack weld a drill guide on the side you need to drill and bolt up the other side with a washer between the template and (manifold?) so you can see the bit line up on the other side.
 
I have had pretty good success with another person helping to drill the hole. First determine if the t-stat housing surface is in fact level. If it is angled you will have to compensate when you drill the hole. Get your second person to help hold the drill and watch from a position 90 degrees (as viewed from overhead) from your position. Both of you get low so you can view the drill directly from the side so you can eyeball the angle of the drill to be aiming perpendicular to the surface from your respective positions. When you drill, guide the drill motor only in the plane you are looking at, and allow your helper to guide it in the other plane that they are looking at. You can get plenty accurate holes in very awkward situations with this technique if you carefully plan. If your helper (or yourself) is not so good at eyeballing what perpendicular looks like, set things up ahead of time with some sort of reference to compare the angle of the drill. You can clamp something near by, or simply use something else nearby to compare how you guide the drill as you go.
 
When using the drill and tap, a couple of things:

Stuff a rag into the thermostat hole, you want to make sure you keep all chips out of the coolant system. Also be careful when you remove the rag so you don't dump chips into it.

Use lots of oil when running the tap in. Once the tap bites (go straight- be careful!) turn it half to three quarters of the way, then back a quarter turn. Keep doing this the entire time. This clears the chips and keeps the tap from getting jammed and potentially breaking. If the tap breaks in there you're fucked cause you'll never get it out.

Make sure you flush out the hole after tapping with a spray solvent using the red straw like brake cleaner to assure all the chips are out.

After that, threading in the helicoil is pretty straightforward, unless you've done a poor tap job or have left chips.
 
Or used grease and a roll form tap and you wont have any chips. Just make sure to get the right drill to match the tap.
 
Thanks for the tips. This is a pic of the damage. Havent touched it in a while but i will probably start tomorrow.
 

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