DiscussMormonism.com

*deep breath*

I bought a somewhat older truck (1991) with wee bit of miles (226K), and have been trying to get it up to snuff. While removing the thermostat housing, one of the bolts snapped, leaving about 1/8” of bolt above the engine block.

I drilled out the middle (using left-handed bits), used penetrating oil, and an easy-out. All to no avail. I then tried using a chisel at an angle to try to coax the bolt along and hopefully knock it loose. And… nope.

So, I had the bright idea of using a tap to create new threads within the bolt for a smaller bolt. In doing so, I snapped the tap out within the hole. Now, I’ve got a chunk of carbide in there that laughs at the various bits I try to toss at it. If I can get the top portion of the tap removed, I think I can get a stud bolt epoxied** into the hole, and then use a nut/washer for that side of the housing.

My problem is getting enough of the carbide tap out to give my last-ditch effort a try. So, any thoughts on how to proceed, or better options/ideas? I’m about 14 hours into what was supposed to be a 30 minute thermostat replacement and radiator flush, and starting to get very stressed and desperate.



**Using a high-heat metal epoxy.

A few of the thoughts off the top of my noggin that I’m thinking about for removing it (or at the least the top of it):

1. Diamond hollow core bit.
2. Diamond burr and a rotary tool.
3. Chisel counter clockwise, and hope to either gradually coax it upwards, or hope its brittleness works in my favor, and it chips to pieces.

The first two would require me buying more stuff… which I really hope to avoid at this point.

My husband suggested drilling a slit across the top of the broken tap so a chisel can unscrew? (He's currently working on my 1999 suburban right now, so he empathizes) If you get the tap out he said depending on the shape of your housing and if it's cast as a whole, use a high-beam C-clamp (?sp, i'm just writing down his words)o hold the thermostat housing instead of trying to epoxy a new stud.

Thank you Lemmie (and thank your husband for me, please).

One of my main problems is that the carbide tap is too hard for every bit that I’ve tossed at it, but I might be able to get a small tipped chisel on one of the sides to try to hammer tap it to unscrew.

Fantastic suggestion with a c-clamp. I hadn’t even considered something like that. It’s a 350 Chevy small block; I can’t quite picture where to position a c-clamp for it to work, but hopefully when I have the engine in front of me, something miraculous will happen.

Been there. Done that. Hardened tap steel is next to impossible to drill. If you still have some of the bolt protruding:

Heat the bolt with a torch till it is red hot. Let cool. Clamp onto the stub with vice grips and back it out.

Elsewise - Weld a nut onto the top of the stub. Back it out.

Worse comes to worse, drill the crap out of it. Remove the old bolt and the tap, then thread and helicoil the hole.

if you have access to a welder, weld a nut on top of your mess

can you break off the housing, or cut it off with a dremmel and then "try" to remove the bolt remains with vise grips, then buy a new housing?

SteelHead wrote:Been there. Done that. Hardened tap steel is next to impossible to drill. If you still have some of the bolt protruding:
Heat the bolt with a torch till it is red hot. Let cool. Clamp onto the stub with vice grips and back it out.
Elsewise - Weld a nut onto the top of the stub. Back it out.
Worse comes to worse, drill the crap out of it. Remove the old bolt and the tap, then thread and helicoil the hole.

RockSlider wrote:if you have access to a welder, weld a nut on top of your mess

No access to welder, and there’s probably not enough bolt sticking out to be of much use. There’s about ¼ of the bolt's circumference that is still protruding above the block, and with the drilling, it’s only 2-3mm thick.

Markk wrote:can you break off the housing, or cut it off with a dremmel and then "try" to remove the bolt remains with vise grips, then buy a new housing?

Unfortunately, the bolt is in the block.




More and more, it's looking like I've got a lot of long hours of drilling ahead of me.

Can you use a bolt to fill in the other threaded opening, leave your stuck bolt where it is also, and then create two new threaded openings that are just slightly rotated from the original ones?

This is looking like a great opportunity to purchase a performance intake. Might even be cheaper in the long run, versus time and expense of tools for surgery to remove that bolt. : )

(I know, I know ... I’m not helping ...)