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More coolant leak



For those who participated in my original thread about losing anti-freeze by some abnormal process, the culprit has been found! This is on my '85 with 45K on the clock.

I was losing coolant by some extra ordinary means because the engine did not appear to be burning it and there were no obvious signs of leakage.
Finally I got ahold of a Stant pressure kit. It quickly located the trouble spot. As I had previously mentioned there was a frozen nut on one of the thermostat housing bolts. Not having been in a hurry to deal with it I left it for a later time. I guess the gasket under that part of the housing was leaking. When I pressureized the system it held for a couple of minutes and then began leaking at that point.
Still not ready to deal with drilling out the bolt I used Bar's stop leak. It appears to have fixed it, for now anyway. I am sure I have not finished dealing with this problem. Sometime when I get real ambitious I will need to pull the Plenum (and possibly the intake manifold) and drill out the bolt.
Any suggestions on the best way to approach that?



Well-known member
Jun 17, 2002
North Hollywood, Ca.
Miss my '62 & '80 4- Sp. Vettes
Before you use the drill method, try using a propane torch and heat the outer casing to expand the metal around the bolt/nut. Now, take a hammer and punch, and carefully tap the nut out using this method. If you get the correct angle and have a punch that took a good deep bit in the metal, you can sometimes salvage the outer threads this way. You will see the nut begin to walk out of the threads if done correctly. Another method is to first, "shock" the threads by giving the nut/bolt head a clean swift tap at the center.


Thanks for the advice. I am trying to physch myself up for this. I was first going to remove the plenum so I could get my impact wrench on it. Failing that I will follow your advice. I have had a lot of luck using the impact tool though. But this appears beyond it's capabilities. I will sure try every method I can think of before I start drilling! I may even take the intake manifild off and take it to a machine shop. I have not had good experience with these types of things in the past. I usually wind up with a hole that nothing will fit into. :(

Thanks again...............


Motor head!!!!
Feb 13, 2001
Valencia, CA,USA
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Fixin holes!

You can buy a centering punch...

1) Spray your rust penetrator down on the broken stud... let it SIT

I assume the stud broke flush with the casting.

2) Give it a FEW whacks

3) Use the torch.

4) Mount the thermostat housing
(make SURE it's centered and use the other hole to lock it)
back on and use the centering punch ( the metal of the Stat housing will hit the outside diameter of the punch ( centering the dimple on the broken stud )... give it a few GOOD whacks making a deep impression in the stud. Remove your stat housing now.

5) Using a SMALL drill bit make your FIRST PILOT HOLE ..... take your time on this.

6) Start working you way UP in size for the BIGGEST easy out you can get.. and DO NOT GET A CHEAP ONE!

7) Pull her OUT.

7) plan B.. if it will not budge keep drilling up to just under the hole size.. the walls of the stud will be SO thin you can carefully tap on the side of the hole and actually bend the old stud off the threads and grab a needle nose and tweek it out ( much the same way you remove a light bulb socket.. when the glass has broke.. and the socket is stuck in the fixture.

Do not be afraid... fear is the mind killer!



Thanks Vig and cntrhub.

Well I am not "afraid" but I have a past! It has not been pretty. My experience in the past has been one of wrecking manifolds, etc.
Oh I guess I have pulled it off a few times but the ones that haunt me are the ones I have ruined. That is why I am reluctant to dive into this one, especially since it is not really causing trouble right now. I realize it is a ticking bomb though.
Probably with my fans coming on a 200 degrees and staying on the engine does not get hot enough to blow out the stop leak. :)

Thanks again guys. I will use your advice when I have used up all of my excuses....:)


Well guys the Bar's stop leak appears to have worked for now. I know it is only a temporary stop gap and sooner or later I will have to deal with the "bolt"! But for now I am mobile. :)

Thanks for all of your advice, I will take it to heart when I drum up enough enthusiasm to tackle it. Trouble now is I hate fixing something that ain't broke! :)
If I make it through the summer I will tackle it in the fall when it is not so hot in the garage. Right now my garage stays at about 90 degrees, day and night. (more excuses!)

Thanks again..........

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