Help with a frozen bolt on the thermostat housing

Ok, I'm totally stuck, and the car's been in the garage for 2 weeks now...

So I had to put on a new waterpump, which went great. I drained the system, took out the radiator and cowl, took off the fan and pulley, took off the water pump, put a new waterpump back on, put everything back, filled the radiator part of the system from the reservoir.

Last step is to take off the thermostat housing, remove the thermostat, fill the engine block with coolant, and put that back together.

I can get the nut off, and one of the 2 bolts, the other won't budge. I've tried an electric impact wrench with a 1/2" socket, I've tried a vice grip with a 3' pipe stuck over the end, I've soaked it with liquid wrench for days, nothing will get it to turn.

I've tried idling the engine, hoping it will draw from the radiator, and I could just refill the overflow, but it almost overheats every time, and the overflow looks no less full.

I either need an alternate point to fill the engine with coolant, or suggestions on getting that bolt out.

HELP! Please!

Thanks!
MC

I'd say that heat is your friend. You'll need to get the stubborn bold red hot to remove it. It's going to have to come off sooner or later and it's not going to get any easier.

If you'd rather wait a few weeks to squeeze a bit more out of the driving season, have you tried disconnecting one of the heater hoses and filling through there?

Id suggest soaking it with some PB blaster, liquid wrench or the like, give it a day or so, and then go back at it with your leverage. If that doesnt work, a nut cracker always will.

*edit* Sorry, didnt see you already gave it a good soak. Have you tried a mild impact on your torque bar?

I'd try PB Blaster. In my experience it's superior! Also, put a bit on, give the bolt a few taps with a hammer and let it sit. Keep repeating for a few days.

I didn't have PB blaster, but I did try pretty much every possible way to get it off, and have been working on it on and off for like 2 weeks with no success, so I gave in today and started drilling it out. I had hoped by drilling off the hex top of the bolt, I could slide the thermo housing up, but apparently the threads start meeting in the cover, not just in the block, so I have some more drilling to do tomorrow. It started raining so I decided to watch tv...

MC

I agree with Derek except for the part about where to apply the heat.
Heat up the block around the bolt and not the bolt (where possible). You want the block metal to expand away from the bolt. Take your time. It's more important than it seems. The corrosion that has the bolt locked to the block has to be broken before that bolt will be free. Soak it with PB Blaster. Heat the block around the bolt. When the residue of PB Blaster starts to boil out of the threads, give it a twist with a good stud extractor too.
Avoid, at all costs, breaking off the stud. Take your time. Give the heat a chance to work.

When things get that tight??? I reach for my torch....also known as the "hot" wrench..
A torch can be your friend... when used correctly

Michael

Rick,

Something that has helped me to get rusted bolts out, without ringing them off is to try to tighten them just a tad, maybe 1/16 to 1/8 turn after soaking them with penetrating oil. If you can get it to move at all, just keep working it back and forth.

Tom

Rick,

I don't think the threads start in the housing. They should only be in the block. So, you should be able to work the housing off. That will allow you grab the bolt with vise grips.

I would use lots of heat!

Let us know what happens.

Bryan

Ok so I drilled off the hex top of the bolt, it came off with ease. Thermo housing won't come off. I think there used to be posts rising from the block (there still is one) with a nut holding the housing down, but at some point some prior owner replaced two of those posts with bolts that go down. One comes out, the nut on the still remaining post comes off, but that last bolt definitely threads through the housing and in to the block.

I'm going to keep drilling until it comes off, and if there's nothing left to remove when I'm done, I'll just tap it and use a new bolt.

That's messed up though...

Actually, if I'm not mistaken, the thermostat housing should have 3 studs with nuts and not bolts. At least that's the way they left the factory on my 'Bs and Minis.

Rick,

Sounds like a plan, do try heat too.

Derek is correct, there were 3 studs that were in the block. Then the gasket and housing slid on with lock washers and nuts holding it on.

Sounds like the PO put an over-sized bolt in, or the housing is just seized to the bolt.

Let us know what happens.

Bryan

why are you trying to fill the radiator that way ? on a 72 Midget you fill it from a brass plug on the radiator, to get them filled faster I just fill it thru the top hose till it comes out the thermostat housing, the top up the tank on the side