partially stirpped thermostat housing bolt, how to fix?

Well I have been having issues with tStats lately so today I did my 5th swap in 3 days.... lets not get into that right now.

The bolts I have to hold the housing on are the same thread but one is abot 1/4-3/8 longer than the other one. the short one was in the drivers side bolt hole and it just stripped out the threads in the manifold. I switched teh bolts sides around, adn it seems to be working, but I hate that I know it is messed up. is there an easy way to fix this in my driveway? I was thinking maybe pull the upper manifold off, drill the hole out, and cut new threads... Is that the easiest way? In the past I have used Heli-Coil to fix stripped threads, should I try that?

I need my car running as I work on Saturday and this is my Daily Driver.

i woulda said try tapping it but not that you switched the bolts that prolly wont cut it.. heicoil it i guess

I've put shaky ones back together like that using that shellac gasket sealer and have had them never leak.

But if you want to fix it, try running a tap down the damaged hole, sometimes you get lucky and clean up a few threads towards the bottom and it holds a lot better. Use a new bolt for that hole. I forget if those are 5/16-18 or 3/8-16 threads. Try to find a bottoming tap since the first threads are already established.

Helicoils are the best way to go if the above fails you.

Bob

Heli-Coils will make your threads better than new. I think Harbor Freight has kits.

Helicoils are lifesavers, agreed. Some good hardware stores have the kits, also places like Auto Barn and Napa sometimes have them. If you have a marine supply store like West Marine, they have them too.

Bob

Well I got to talking to my neighbor and mentioned what I had done to my Maro. He said the he had the kit left over from when he did the same thing to HIS Maro 7 years ago. so he went and dug it up, I went out and bought brand new stainless 5/16-18 bolts took off my upper plenum, moved a few hoses, stuffed a rag into the tstat housing adn drilled tapped, and helicoiled my way to nice new threads. WOO-HOO ot dont leak!

But now my oilpressure sender is leaking for my autometer guage and Im out of teflon tape.... it never ends. but the oil leak is simple.

Thanks for the advise guys. It worked like a charm.

Helicoil To The Rescue!

You're better off doing it right. I used to do a lot of work on boat engines and got good at doing them. There is even a fix for when you strip out a helicoil!

Bob

what do you mean bob? yo dont agree with Helicoils?

i dont know why he wouldnt, there great, lifesaver in racing

I'm very big on helicoils. I use them quite often in aluminum parts.

I was saying that there are products known as oversized helicoils as well as other items for when the original helicoil fails.

You have to drill a bigger hole, thread it and install a special insert, some (like Keenserts) have special locking tangs to stake them in place.

Bob

ah ha. Gotcha. I thought you were trying to say there is a better way to fix it thatn using HeliCoils. My bad.

Just curious which is stronger and less prone to stripping, Helicoils or just re-tapping the aluminum? I was thinking about that, Why not just re-tap the holes in the manifold rathr than tap, then insert a HeliCoil? Im guessing that since the Helicoil is SS it will hold better against the SS bolt, but it is still attached to the aluminum manifold..... Im confused.... :)

ahh i understand now

Since the manifold is aluminum, the only way to re-tap it would to go to the next thread size up. Which would probably work out ok and you might have had to open the holes in the water neck.

From the factory, it is cheaper to just drill it and tap it. Adding a helicoil adds costs and they watch the bottom line on crap like that. Since its not something that comes apart often, most of the time that's ok. Helicoils are mainly used for hardware in softer metals that comes apart often, like in tooling or as a repair.

You do get some mechanical advantage in holding power by using a helicoil as the outer diameter of the thread is larger.

Bob

haha, or..on my v6 2.8'er (the beater) i put the t-stat back on with 'quiksteel' that stuff is amazing. i couldnt re-tap it because my DAD broke the bolt in it, and the drilled it out..but he drilled it crooked!! =/ so i just drilled the rest out, stuck a bolt down there, quick steeled everything. its pretty amazing stuff..sets in less than 5 min pretty hard, and in 30 you can crank her up!