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Dumb mistake, I think -- stripped thermostat housing bolt

51K views 19 replies 16 participants last post by  underdog305 
#1 ·
This happened as we lost daylight so I didn't check to be sure, but I am pretty sure we stripped the thermostat housing bolt.

Engine hasn't been running for weeks, got it to fire and we're leaking coolant (little dribble) from the thermostat housing. So I get my sons to pull it, clean it up, new gasket goop, find the torque wrench -- and the top bolt turns easy below 10 ft.lbs......

Do you think I can helicoil it on the engine, or should I pull it and take it to a shop that can be sure of square?
 
#4 ·
heli coil

You can either heli coil or clean the hole out and retap it for a larger bolt for either steel or alunimum. You will have to drill out the corresponding bolt hole in your thermostat housing if you elect to go with a larger bolt. If you already have drill bits and taps, thats the cheaper way to go, and you already have the stuff to do it.
 
#6 ·
I have fixed lots of thermostat housing bolts, ether striped or broken and rusted out. No need to remove the intake. If the hole goes through into the water jacket, just use a magnet if it is iron, if you miss some they will rust away in no time. On alum. intakes I just stuff a rag in the thermostat hole. Drill it out and tap it or helical it, or install a stud. any of these methods already posted will work.

Troy

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#7 ·
This is in a straight-six guys --- thanks for the good advice. I think I will probably go the stud route, that should be simplest and quickest.

One of my sons mentioned in the other's absence this afternoon that his brother thought the torque wrench was screwed up... he said why didn't you tell somebody -- a few hours later I am now calm........
 
#9 ·
Personally I think that the helicoil is much better. By doing this you now have steel threads that will not pull out. If you JB weld that helicoil in place it will last forever. Then you can stud it or whatever. The helicoil kit will cost you $20, but if you wrench very much it will come in handy again.

Chris
 
#10 ·
You know that's what I love about this board, a lot of thought and experience. Now I have to reconsider my plan....

and the local store doesn't have either the right studs or a helicoil kit in stock, and I am too busy working to shop around much -- thank God for McMaster Carr...

3 more budweisers and I'll make a decision. Thanks all.
 
#11 ·
Any parts store should have helicoil kits.

Troy
 
#12 ·
Update -- success!

Thanks to all for their insights. Wanting to be prepared, I had a helicoil set ready at hand.... but first I checked out 67 Deuce's observation...

He was right, pulled out about 3 or 4 threads, there was another 3/8" untouched. Cleaned it all out with a thread chaser tap and got a longer bolt.

Now I can't wait to strip another so I can try the helicoil thing!
 
#14 ·
The siplest way to fix it is to find the next size bigger in a metric bolt and retap it. Now I agree that this isn't as clean as doing it "right" but it works and you don't have to buy an expensive helicoil kit. And as mentioned, there may be a couple good threads down in the hole to get a stud into. I have always used red or green loctite to secure those.
 
#15 ·
In an effort to keep the tapped threads from falling into the water jacket etc... Simply load the recess' of the tap with grease. There will be three "concave" sections in the tap, once you begin to tap, the grease will hold all the metal shavings. if you feel the tap is filling up quickly, just simply clean out that grease and add more.

May be a little late for this particular thread... but will give ideas to future stippers. ;)

ron
 
#16 ·
nice

I always stud my thermostat hosuing. If you can get the bolts out just JB weld a set of 3/8" studs into the thermostat bosses.



i like that - thats a good idea. r4r imma try it out shortly

-the price i pay for being to lazy to go get a torque wrench.



r4r
 
#18 ·
pmeisal,

key word in the problem..."son"

For iron, I keep a set of bits and taps on a old speaker magnet. Drill slow and keep brushing the filings off with an old tooth brush.

For aluminum, I heavy coat the bit or tap with anti-seize, you want to use it anyways. Hate that stuff, gets on everything, hard to clean up.
 
#19 ·
on a gm inline, (250-292 c.i.), even if u had to put in a helicoil, the thermostat housing bolts up to another aluminum housing that bolts up to the front of the cyl. head. all u have to do is take the whole assy. off. that way u can do it without worrying about getting any shavings in the water jacket. also, with the brackets that go on an inline 6, 1 side of the thermostat housing bolts needs to be longer to accomodate for the powersteering or a/c bracket. which bolts up on the drivers side of the thermostat housing base. just under the housing itself. (holds powersteering on my car, see pic).
housing and bracket
 
#20 ·
Just curious? Has anyone considered that Helicoils will corrode because of dissimiliar metal contact in a aluminum manifold? If the threads do go into the water jacket the coolant will help things along too. It may take a while to corrode, but it's an eventuality. Then your right back where you started. I'd go the route of a tap and a stud. :thumbup:
 
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