Removing Thermostat Housing

[54blackhornet]

I would like to replace the thermostat but the housing has never been touched in years. I certainly don’t want to break a bolt off and end up with a drill and tap exercise. Any advice other than heat and good penetrating oil ? Not sure if it’s the original housing ? Thanks

[1970cstblazer]

When I replaced the thermostat on my 1970 Blazer, the bolts came out ok. There was a small amount of pitting on the housing that was addressed with a small mount of grey RTV with an original NOS GM thick gasket.

[67C10Step]

I understand your concerns. Had to do the weld the nut on trick for both mine when I replaced the thermostat. Intake has since been removed, blasted and painted.

[geezer#99]

Use a flat headed drift and wack the bolt heads a couple times.
That’ll loosen any crap stuck in the threads.
Then tighten slightly.
Then loosen slowly.
Once loose thread them in out to clean the threads.

[54blackhornet]

When I was younger I made a lot of stupid mistakes like trying to remove stuck fasteners by using brute strength. After a while one learns that patience beats strength every time. I knew by the look at that aluminum housing I was in for a fight. Not certain why aluminum was chosen , knowing about corrosion between steel and aluminum ? The only reason I wanted to change the thermostat is because it has been in place since early 2000’s. Drilling a hole in the head of the bolt for penetrating oil is a novel idea but has anyone ever successfully done it ? Thanks for the suggestions.

['68OrangeSunshine]

Originally Posted by 54blackhornet

I would like to replace the thermostat but the housing has never been touched in years. I certainly don’t want to break a bolt off and end up with a drill and tap exercise. Any advice other than heat and good penetrating oil ? Not sure if it’s the original housing ? Thanks

L6 or V8?

[54blackhornet]

Original 307 ! I believe that the housing is aftermarket because it has a provision for a carb return spring on it which the Dual Jet did not call for. I have never had need to remove it . Cooling system works fine so I just left the sleeping dog lie.

[1970cstblazer]

Originally Posted by 54blackhornet

Original 307 ! I believe that the housing is aftermarket because it has a provision for a carb return spring on it which the Dual Jet did not call for. I have never had need to remove it . Cooling system works fine so I just left the sleeping dog lie.

The original housing on my 1970 Blazer part number 3877660 is casted with that provision.

File pic not mine:

[weq92f]

Originally Posted by 54blackhornet

When I was younger I made a lot of stupid mistakes like trying to remove stuck fasteners by using brute strength. After a while one learns that patience beats strength every time. I knew by the look at that aluminum housing I was in for a fight. Not certain why aluminum was chosen , knowing about corrosion between steel and aluminum ? The only reason I wanted to change the thermostat is because it has been in place since early 2000’s. Drilling a hole in the head of the bolt for penetrating oil is a novel idea but has anyone ever successfully done it ? Thanks for the suggestions.

.

There's at least one reference on the Internet to the drilling the head method. First for me!

Quote from the comments section of the article below.

Mike Dunn
October 2, 2013 at 8:18 pm
I drilled a 1/32 inch hole in the top of the head bolt and squirted PB penetrate into the hole. It works it way down the shaft of the head bolt to the threads.

https://www.eastwood.com/garage/10-t...d-stuck-bolts/

-Kevin