Broken Thermostat Housing Bolts

[BJSnooper]

SURPRISE! I broke the two bolts which hold the thermostat housing together. So much for just a quick thermostat swap.

Anyways, I have the broken ends soaking with some penetrating oil on them. My question is - is the upper half of the thermostat housing have threads in it? Or is the only threaded portion in the lower half of the housing? I broke the heads of the bolts off, so can I theoretically pop the housing in half? I tried tapping it with a rubber mallet and it wouldn't separate but I only tried very lightly.

I have my drill, bits and extractors ready!

(both heads snapped off, the one on the upper right just snapped a little lower down into the hole)

 

[Poser]

Only the lower section is threaded.

The dissimilar metal corrosion between the aluminum and steel is awesome in this application.

I would heat those bolt remnants up and use a vice grip on them to get them out of the housing.

 

[BJSnooper]

Only the lower section is threaded.

The dissimilar metal corrosion between the aluminum and steel is awesome in this application.

I would heat those bolt remnants up and use a vice grip on them to get them out of the housing.

Awesome. That's what I figured. Thanks for the response.

 

[alittle1]

I would squeeze a 2 inch putty knife between the two surfaces and wiggle it around to separate the housing from the head. After, I would lay a nut one size larger over the shaft of the broken bolt and mig weld it to the bolt. While it was still hot I would put a hex socket (six pt) over the new nut and remove it. If the other one is broken flush with the head, I would lay a nut on top of the bolt and weld it around and around with a mig welder until the void in the nut was full of weld and then let it cool a bit and take a hex socket to it also.

Clean up the heads with tap and put anti-seize on the threads of the new bolt and tighten her down.

 

[BJSnooper]

Here's a little update to the thermostat housing progress. I managed to get the 2 halves separated with a mighty struggle. With heat and vice grips, I got 1 bolt out but the other didn't budge. Extractor and heat did nothing. I had to drill it out and it still fought with me. I ended up drilling the hole a couple sizes larger and re-tapped it to accommodate a larger metric bolt (see the pictures below)

I cleaned all the crap off the surfaces and insides, scraped the edges out and got ready for reassembly. It was going to be a perfect night... The wife was watching the stupid Oscars and wanted me out of the house so she couldn't hear my complaining. The cruiser gods struck down on me, the thermostats weren't the same! I had to watch the retarded Oscars with her... Off to get the correct part this time.

Hopefully full reassembly will take place in a few days.

 

[BJSnooper]

The two different thermostats. The old thermostat is in rough shape as I had to mangle it to get the housing halves apart.

 

[CaptainAwesome]

The two different thermostats. The old thermostat is in rough shape as I had to mangle it to get the housing halves apart.
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Sorry for asking about an old thread. Do you remember if the new thermostat you got had an o-ring with it and if it was the high flow one?