Hey fellas, we're in a bit of a pickle here. I'm replacing my thermostat housing, and one of the three bolts to get the lower part off is not budging. We ripped off the housing, broke off the bolt, and tried tapping into it to get the last bit out, the part with the threads. In doing so, the tap bit broke, and is flush with the bolt left in there. Any ideas on how to get the bolt out now? We were thinking last resort to ignore it and make a gasket with RTV Sealant, would that hold against the pressure running through the thermostat housing? Please help, we are at a loss of ideas. Thank you.

 

No, it won't hold very long.

Reverse drill bit and reversible drill will usually get out stuck bolts and even taps.

Start with smaller bit.
The vibration of drilling and the direction(reverse) will usually start bolt/tap to unscrew.

Worse case is that it doesn't unscrew and you have to use an eze-out in the hole you drilled

 

When I do this sort of thing, I find Snap-On bits stand up well.
Here in Canada Canadian Tire sells reverse drill bitts, but they break very easily.
You end up with a bigger mess.

 

Update is that we got cobalt bits, we are going to try to drill out a hole up to 1/2 inch, put a hela coil in, fill it with another bolt, chop it off, tap it, then make threads for the bolt that holds the thermostat in. I will update accordingly.

 

Reverse drill bits, only way to fly, lol, just saying, since I started using this method 20 years ago it has served me well

Once you have it ready to tighten up you only need 15-18ft lb torque, so almost just hand tight.

You can use anti-seize on the threads, same as exhaust bolts, to slow down the rusting and prevent repeat situation.

 

We drilled out the hole, tapped it and filled that with a brass bolt we made on a lathe, drilled another hole closer to where we needed to bolt down the housing, filled that with another brass bolt we made, drilled through the housing to ensure accuracy into the mount again, tapped that hole, threaded it for the housing bolt, and that ended up working. Now we are about 20 hours in and we just put the new lower housing on. We still need to replace all of the hoses, put the intake back on, and flush the system.

 

Sorry I am late to this party...
The NEXT time you have a broken bolt to extract leave the drill and taps in the cabinet.
Use a MIG or stick welder.

Assuming the broken end is flush or nearly so to the surface:
Hold a nut over the broken bolt and reach in and starting on the broken end of the bolt bring a bead up inside the nut welding the nut to the end of the bolt. Let cool and turn the bolt out with a wrench.

If the broken end of the bolt is recessed any distance use a stick welder. Hold a washer over the hole and reach in with a thin rod (7018 works well) and bring a bead up to the washer. Now weld a nut to the washer. Let cool and turn the bolt out with a wrench.

WAY faster, easier, and less frustrating then mucking about with drills and taps or extractors.

Makanak

 

Before we ripped the bolt off, we tried welding a nut to the bolt, but it was tough because the thermostat housing was still in and as it turns out, is flammable. I think after that, we abandoned all welding possibilities, we aren't very skilled with it.
On the plus side, we have a new tap and die set.

 

For a conclusion, 25 hours after starting this project, we got everything back together(except for the actual thermostat and the gasket that goes around it), and we were going to flush the system with distilled water. My buddy had done this with his jeep. We poured the water in and it pouring out of the thermostat housing, we're thinking because the gasket(o-ring) isn't in place. We didn't think that the o-ring was the only thing keeping the coolant(or water in this case) in the housing. My truck is currently sitting in his driveway, we will continue the project this Friday.

 

Here are some pictures.

 

Yeah, that T-stat housing is an aluminum-magnesium alloy. Whenever possible get the outer part off so you can gain easier access to the broken bolt.

What is important now is a suitable fix has successfully been implemented!

Makanak

 

Yes, but when we went to flush the system, the water poured down around the engine block. We suspect it was the lack of gasket and thermostat, we didn't think it would leave it so open. We will figure it out on Friday.

Wow, those picture attachments worked really well, huh? :/

 

I use photo bucket, up load them and simply copy the link directly here from the source.
The ads are a pain in the butt though.

 

Another late comer... did you check the housing and manifold for cracks after you tore off the housing and broke the bolt ?

The new bolt... Make sure of the proper length, so it doesn't bottom out !

 

The housing was cracked, that's where the original leak was coming from. The manifold was good.
Got outside yesterday to go to work, found a neat little puddle of coolant below my radiator, around where the drain plug and lower hose connect. I picked up a pressure tester today, and I'll look at it at some point this week. -_-

 

Turns out the upper hose wasn't fastened all the way on, that was an easy fix.