thermostat

Sounds like you may have cross-threaded that bolt, Dude.

especially how

Ok, it's confession time again. One time it was about -300 degrees on the Kelvin scale and I had the same problem with the bottom bolt except I just could not get it started with my fingers. If I can't start it with my fingers I am not going to force it. After many tries and early in the AM I decided to start the bolt without the T-stat housing in place. Then I hacksawed the outside edge of the housing enough to slip over the bolt and I was done and moving in just a few minutes and nothing ever leaked. It was an emergency and the housing is pretty cheap any way. If it's not an emergengy I'd take everything off and work with that hole until the bolt went in easy. You might even need to retap the hole. It does sound like you cross threaded that hole if it went in hard and especially if it started at an angle and then straightened out. Even Stevie Wonder could see that.

thanks for the replies.

While trying to initially install the bolt, I must have started it 10 times. The bolt went into the other hole just fine, and I could start it with my fingers in either hole, but it soon became tight to turn in the bottom hole. On close examination, it is not completely seated, which I suppose is why the tstat leaks. But it does look straight. It may lack about 1/8" to 1/4" to be completly seated.

I think I might be able to remove the bolt and install a couple more lock washers to tighten. However, you are probably right-it may very well be cross-threaded.

You could have a bunch of crap/water in the hole. Blow it out with compressed air and try again.

Aiyiyi!

Don't do anything without at least chasing the threads out with a proper sized tap. Everytime you screw that bolt in you are doing more damage to the threads. If it is badly cross threaded, you will need to drill the hole out and put in a heli-coil. Even this is not a big deal and it is a permanent fix.

There is very holding strength in a cross threaded hole. You don't want to be springing a leak some day far from home.

Stephen --> Sprung a few leaks in my time...

The OTHER Kev> On Wed, 30 Mar 2005 20:25:39 -0600, "stevie" snipped-for-privacy@dum.org wrote: >

I'm assuming the difficulty in getting the bolt in was/is due to crap in the hole.. If there's a bunch of junk in the hole, the bolt is going to try to compress it and that material has nowhere to go. Since this is the lower bolt on a thermostat housing, it's possible some coolant wicked into the hole. Fluids don't compress and trying to run a bolt into a hole in that instance will prevent it from seating all the way and it will be more difficult to turn.

Blow the hole out and try again. If it's still difficult, then by all means, chase the threads.

thanks again for the replies.

I'm going to go out and retry some things this afternoon (Thurs). You may have a very good point about stuff in the hole. I examined the bolt (earlier in the week) and it did not appear to have bad threads; plus, it went easily into the top hole.

I'm assuming the difficulty in getting the bolt in was/is due to crap in the hole.. If there's a bunch of junk in the hole, the bolt is going to try to compress it and that material has nowhere to go. Since this is the lower bolt on a thermostat housing, it's possible some coolant wicked into the hole. Fluids don't compress and trying to run a bolt into a hole in that instance will prevent it from seating all the way and it will be more difficult to turn.

Blow the hole out and try again. If it's still difficult, then by all means, chase the threads.

I'm going to jump off a bridge.

I reinstalled thermostat. The bottom bolt seemed to go in OK-I do not believe it is cross threaded, even though it is somewhat harder to turn. It seems to tighten OK.

I think what has happened, both times, is that the tstat does not stay in the indentation of the elbow but drops a little and creates an opening between elbow and engine. This happens when I reinstall the elbow with new thermostat. The water leaks now, even with the engine off. So I'm pretty sure I haven't got a good seal. I am using sealant and new gasket.

Can anyone suggest how to hold the tstat in place while reinstalling? I have Chilton manual . It says turn tstat clockwise to anchor in the elbow, but I don't see any way to anchor that by giving it a twist. The Autozone how-to site says the same thing (it's a reprint of Chilton).

In addition, I am placing gasket on the engine (using sealant) and placing tstat in the elbow, which is how indicated in the Chilton. Is this correct?

One of the biggest problems is accessing the tstat. I have been removing the AC bracket, radiator, and fan. This just takes some time.

The Autozone site shows pictures of someone removing the bottom bolt, with another hand near the tstat. Whoever is in the picture must have a right arm at least 4 foot long. Anyway, the picture is an '83 302 V8, which looks about the same as mine.

Any suggestion would be appreciated.

"The OTHER Kev>Aiyiyi!

I'm assuming the difficulty in getting the bolt in was/is due to crap in the hole.. If there's a bunch of junk in the hole, the bolt is going to try to compress it and that material has nowhere to go. Since this is the lower bolt on a thermostat housing, it's possible some coolant wicked into the hole. Fluids don't compress and trying to run a bolt into a hole in that instance will prevent it from seating all the way and it will be more difficult to turn.

Blow the hole out and try again. If it's still difficult, then by all means, chase the threads.

I have used a couple of spots of sealer to hold the stat in place, but normally what I did was use the sealer to hold the gasket to the elbow instead of the block- that always worked well. If the bottom bolt is still that hard to run in, I'd do like Kevin said and chase those threads first. You have nothing to lose by doing it, and you may save yourself some unnecessary work down the road. Good luck! SC Tom

Are both bolts the same length? Some housings have different dimensions between the mating surface of the housing and the boss where the head of the bolt makes contact. In either case make sure you chase the threads before another attempt. Put the thermostat in the housing and apply Form-a-gasket (the really sticky type) to the housing. Apply the gasket and wait an hour or so for the Form-a-gasket to set pretty tight. A little heat under a light helps. The gasket should hold the thermostate in place during installation. Be sure to use copper RTV on the gasket where it faces against the block. Should you have to remove it again the housing will pull right off taking all of the gasket with it. If you need to replace the gasket you'll have it out of the vehicle where it's easier to remove the gasket and any remaining debris. Good luck!