Head of bolt snapped off when attempting to remove thermostat housing

[Mario81587]

Today I was changing my thermostat and thermostat housing as well as doing a full tune-up and cleaning the engine bay. I went to take the last bolt off and the head snapped off (as seen boxed in red in the picture). I was thinking about just breaking the rest of the housing and using vice grips to remove the remaining part of the bolt. However, I'm worried about the plastic tabs breaking off and going into the cooling system. I'm doing a full cooling system flush, new radiator, and new water pump. Where exactly would these tabs fall in to if I did break the rest of the housing off? Thanks for any advice!

- Mario

 

[swshawaii]

Is the housing loose? If so, you should be able to lift the housing 1/2" without breaking tabs.
Without coolant, if any of them break, they should be easy to retrieve. See step 6, pics 2/3.

http://bengrosser.com/howto/fordthermostat/

 

[Mario81587]

The housing won't budge at all. I was going to attempt to lift part of it and rotate it, but the bolt that snapped is around the part of the housing that has the three tabs. So if they do break off, they won't go far down into the cooling system? Thanks for your help.

- Mario

 

[swshawaii]

You need to break it free one way or another. Use a hammer with a wood block, tap around it, and gently pry up.
If everything's disconnected, including the bypass hose, it should come loose. Sealant was not used at the factory.
IMO, the broken bolt is a bigger issue. I wouldn't worry about the tabs breaking, they won't go very far. Go for it.