Broken Thermostat Housing Bolt. Now What?

[Racer65]

Didn't tried it yet but the way they put studs in is they put two nuts on the stud and in which direction you want to go you neither put a wrench on the bottom one or top nut...In this case on the bottom one I think..they lock to each other.you don't even have to weld nothing on it....but I never tried on stuff like this...heat it up before as everybody says..be carefull...

You know I've been thinking exactly about that...

Another out of the box thought is to screw on a non-metric nut so that it gets jammed.

 

[Poser]

You can heat that up without issue...

Been there, done that, many, many times.

No big deal.

If the threads get jacked removing the broken bolt, install a thread insert and call it good.

Any of these that I touch, get 10.9 hardness fasteners installed back into the housings with anti-seize.

 

[elkun1]

I would shorten the bolt up and weld a washer on then a nut to the washer. leave enough room so you can get a piece of candle on the bolt. the paraffin will wick in like penetrating oil and really helps on saving threads. if you pull the threads do as poser said and put in an insert. If all else fails pull out the edm and have fun. don't forget the anti seize.

 

[Weber Sarge]

Paraffin or canning wax is an old machinist's trick - heat the snot out of that aluminum and melt some into both sides of the threaded hole - that bolt will screw right out . I'd say it's best to remove the housing - if nothing else it gets the antifreeze out of the way and allows new fasteners to be used at both joints - coat those bolts in aluminum-specific anti-seize . On all my stuff the thermostat housings get studs instead of using bolts - stops the whole issue of tearing up the housing . Sooner or later , any aluminum part with a steel bolt is going to oxide , better to stop the problem the first time .

Sarge

 

[georgia fj40]

Take a look at "Irwin Twister's" You tap them on with a hammer then use a ratchet. Or just kroil and good old vise grips.

 

[JAFO2014]

Apply heat, just not too much. It doesn't take much heat to break things loose. You just want the metal to expand a little. If it were me I'd heat around the stud, then put a small pipe wrench on the stud and have it out in a couple minutes. Welding on a nut works great as well. You are lucky that you have the stud there. Best thing that could happen. If it had snapped off even with the housing you'd be drilling.

If you have to drill, you drill with a very small bit down the center. Then a drill bit just about the size of the bolt. Then a lot of times I can just run a tap in the hole and clean it out. Worse case you have to install a heli-coil. They work fine by the way. You drill out the hole using the heli-coil drill bit, which is a thread size bigger than the bolt thread. Then tap with the heli-coil tap and then screw in the heli-coil. All fixed.

There is always a way to repair threads in something metal.
And your stud is nothing. I had to get 1" studs out of the drawbar on my 1949 Caterpillar. Lots of heat and a 2' pipe wrench.

 

[Racer65]

Got the torch and vice grip ready. Just want to run through one more question: Heat the broken bolt or the housing?

I also want to loosen the two bolts holding the lower housing to the engine. Apply heat to the bolt head right?

 

[Coolerman]

Yep heat the BOLT as hot as your torch will get it without melting the aluminum. Let cool, then try to wiggle it.
Water Pump toward bottom of page 1. Link to my method of getting this exact broken bolt out. I did not describe the heating I did with a Mapp gas plumbing torch when I wrote that.

One other thing I did was run a tap through the threads once you get the bolt out to clean out the corrosion. 8mm x 1.25 tap.

 

[skully3]

Kano Kroil is by far the best for penetrating oil. I just went through this recently and was the only bolt that I broke off during my complete engine rebuild. If it happens to not come out like mine did, drill out the broken part and put in a m8 insert. If your not worried about stock drill it thru and put a long bolt up from the bottom. The housing is close to the head of the bolt and holds it from spinning. as far as the tough bolt in the head, soak with kroil and try tightening first slightly, then back and forth with a good feel. Aluminum corrosion is worse than rust IMO.

 

[skully3]

Metric and Multi Standard have the best aluminum inserts. a pic for reference.

 

[micruz60]

Tightening first is a good step, breaking the galling corrosion between the steel and alu. Then reheat the bolt, add preheated penetrating oil to hot bolt hopefully it'll follow thread into alu. Easy does it.

 

[Tools R Us]

With the heat and penetrant, hammer tap on the bolt, at the base, sideways to the bolt. Most cases need to use a punch, as much as possible, go around the bolt, attempt to walk/move the bolt sideways in the threads. Obviously not hard enough to break the housing, but, will often break up, crunch, the corrosion, allow the oil to penetrate, giving the removal attempt a higher chance of success. When the bolt starts to turn, often best to turn it in and out a few times, this works the oil in, improving the chances of saving the treads.

 

[Bear]

Racer,

I agree with the comments made about threads and anti-seize.

Lucky you sell the housings...........since too often, no matter how the broken bolt is extracted, much of the soft aluminum threads within the housing will be extracted along with the bolt remnants. You can tap for the next larger size bolt, or replace the lower housing. The bolts going into the head don't cause these problems, as the head is steel.

Because this has happened too many times for me, I have taken to installing studs, not bolts, into lower housings with some Loctite, cured, and then some anti-seize before washers and nuts, so that the next time the thermostat is removed-- no more broken bolts. Yes, it's kind of funky, but for me it pays to look ahead to the future sometimes.

I also have found this thread stripping to be a problem with the aluminum intake manifolds when disassembled from the exhaust manifold. It appears that a lot of heat doesn't play well with aluminum threads and steel bolts, at least from the factory on these old-timers.

So far............everything I have ever anti-seized has disassembled when needed without a problem. However, I would need to evaluate this 50 years down the line to see if this method really works better than the 50-year old factory dry install.

HTH

 

[brian]

So far............everything I have ever anti-seized has disassembled when needed without a problem. However, I would need to evaluate this 50 years down the line to see if this method really works better than the 50-year old factory dry install.

HTH

i can give you a 15 year performance review.
in a previous life i fabricated and rebuilt rock crushers for a living. the heart of these steel beasts lives in a wet an gritty and very unpleasant environment 8months of the year, the other 4 they sit idle exposed to the winter weather.
when i was young an green i helped assemble one new.
in the following years we rebuild many machines, all originally assembled before my time, and with little or no anti seize. they fought till the end not to disassemble. most parts un-reuseable as a result of the effort required to get them apart.
15 years later as head of the weld shop i over saw the rebuild of that first machine. we had used much never seize in it, some said too much. in this case, many of the parts could have been reused. it came apart in hours, vs the days it normally took.
that machine actually book ended my time there, the first became the last, as the shop closed shortly after finishing that rebuild.

 

[Racer65]

The nightmare scenario has now manifested!

Heated the broken bolt with Mapp torch 6 different times to no avail. Vice grip doesn't move it.
Took out the breaker bar to try to remove the lower housing bolt...and the bolt has snapped!
I'm taking it to @orangefj45 . Sorry Georg...

 

[micruz60]

Aaugh!

 

[Racer65]

Racer,

I agree with the comments made about threads and anti-seize.

Lucky you sell the housings...........since too often, no matter how the broken bolt is extracted, much of the soft aluminum threads within the housing will be extracted along with the bolt remnants. You can tap for the next larger size bolt, or replace the lower housing. The bolts going into the head don't cause these problems, as the head is steel.
HTH

Actually the '79 to '80 housings are unobtainium. Luckily, I do have a couple of used spares. As you can see, my housing is really at the end-of-life.

 

[brian]

so much for rust free west coast trucks

 

[Racer65]

so much for rust free west coast trucks

Should've done this job 17 years ago when the car was newer. This is what I get for keeping the car original. None of these bolts have been turned since it left the factory in Feb 1980.

 

[Bear]

Thanks for the testimonial, Brian--now I can hold my head high when my daughter asks about my "silver hands" !

Racer, sorry that happened.
What makes that bottom housing so special--is it the VSV port? I thought it was the upper angled neck that was the rare part.