Four Bolt T-stat Housing Removal

[TCosta67]

I've read and attempted to follow the suggestion on how to remove a four bolt thermostat housing shown in the Cooling Section. I've sprayed the studs with PB Blaster, liquid Wrench, Marvel Mystery Oil, WD40. The liquid keeps disappearing so I believe it's doing something. I am using a large rubber mallet for the last four days. This sucker will not move. Has anyone had any success with removing the housing with another method? Since this photo was taken I've removed the sheared bolt . I've been having overheating issues and I am wondering if this cockeyed thermostat has anything to do with it...

[Bwk2000]

Welcome. Try a propane torch to heat the studs (15 sec or so each). Then, as it’s cooling down, keep hammering the housing with the rubber mallet and keep spraying the stud base with PB Blaster. Clean it all off and repeat until it comes loose.

PS. That thermostat is definitely part of your overheating problem.

[FergO2k]

Wow, well that cockeyed thermostat could certainly have a LOT to do with unpredictable/incorrect coolant flow, who knows that it is doing!
Unfortunately, the tower stands some height, like 3 inches, so while the fluids are penetrating, they are eating away very slowly at the top layer of the earths crust!
Meanwhile, the hammer taps have broken the crust at the first 1/16" base, but now there is the 2+ inches in between. (and we don't have 45 years to wait!)
So, short term to get her moving/running, is reach in and clip that upper web of the T-stat, and start ripping pieces out. (and run without a thermostat)
Long term, get a grinder or dremel and cut the web / bosses on the OUTSIDE of the studs at upper-right and lower left.
Draw a line from broken stud to open hole, call that 6 and 12 o'clock.
On upper right stud, cut at 2 and 5 o'clock. (or if 5 o'clock isn't accessible, cut at 3 o'clock and then start filing back, if nothing else, your PB Blaster now has room to work) Hope it is obvious, but when filing & cutting, stuff a rag in the hole.

Wait, you removed the sheared bolt, but it should have been equally as fused to its casing, so can you double nut the studs and creep them out on their own? Tension on them and then heating the tower may break loose the crust, which is bonding the studs to the tower right now.
Not huge force on the studs, just someone pulling while you heat the local areas of the tower, then SNAP! (and both studs and tower are toast at that point)
Or you can go full-medieval and just cut the tower completely off like 1/4" above the current thermostat. Then flush the system by putting pressure on block opening, (freeze plug hole) so water is flowing from small passages and pushing the metallic #$%^ back out this hole.

[TCosta67]

I have tried the double nut trick, too. I put so much pressure on it that I was afraid I was stretching the studs. It took me about an hour and half or two hours to get the sheared bolt out. I broke two bolt removers/drill bits off in the bolt. I ended up screwing it out of the bottom with vise grips...about ten degrees at a time.

[FergO2k]

There you go, well you tried your best. I will have to yield to those that have done this before. (small explosives? just kidding!)
This may not be effective, but vinegar is acetic acid, and eats at water mineral deposits, so can we faux-cap right on top of the thermostat and then fill the tower with vinegar for about 10 days???

[redroadster]

Muratic acid eats rust and corrosion
Yes B X tra careful

[ppeters914]

Just one reason I got rid of that goofy tower. I would really like to know the design and engineering decisions that went into that.....thing.

While not ideal, if you have to destroy the tower, then so be it. Several vendors sell a replacement. I also have a slightly used one that I'll probably sell.

Key thing is to get the studs out of the head and the mating surface isn't grrrr'd.

[FergO2k]

And be careful with that Muriatic acid (get it from the local pool guy) as it is way concentrated and you need to be wearing a face shield or chem goggles at the least when using it.

[david premo]

Simple, take and cut the tower on both sides of the long studs all the way down to but just short of the head break off what is leftover and back the studs out.

[jr02518]

I can second the above, we had to cut mine off the housing. It was not going to come off in one piece. We did save and reuse the cap base.