Lower thermostat housing holes both stripped

[Praxiss454]

Rebuilding the 230 in my 65 GMC. My old lower thermostat housing is in fine shape, EXCEPT both of the bolt holes are stripped. I previously had it held together by using longer bolts for the water outlet, and then just using nuts on the bottom end.

Do you think this is advisable long term?

Seems like my options are
1. Run it as-is, using longer bolts and compressing it together that way
2. Tapping the existing lower housing with the next size up thread.
3. Continuing to try to find a housing for sale. Can't find one at Napa, O'Reilly, Rock Auto, or Amazon.

[Wrenchbender Ret]

Put Helicoil inserts in them. They come in a kit with instructions & all you need is a drill. The size is 3/8" coarse thread.

[Praxiss454]

Originally Posted by Wrenchbender Ret

Put Helicoil inserts in them. They come in a kit with instructions & all you need is a drill. The size is 3/8" coarse thread.

That's a good idea, thanks for the suggestion. I already have a tap set so I should be able to just buy some inserts.

[kazoocruiser]

You could run long bolts through the housing and use nuts on the back side if there is clearance.

[Praxiss454]

Originally Posted by kazoocruiser

You could run long bolts through the housing and use nuts on the back side if there is clearance.

That's how it was set up when I tore it down. I just wasn't sure if that was a good long term solution.

I have another problem now. I was disassembling the housing because the fittings on the sides were corroded, and while one of them backed right out, the other one snapped off flush with the body. Not sure the best course of action here. I could look for a ~5/8ths screw extractor that would work to remove the rest of the threads, or some other solution.

[nsb29]

Put some heart on it first to burn the rust off then use your easy out

[kazoocruiser]

Originally Posted by Praxiss454

That's how it was set up when I tore it down. I just wasn't sure if that was a good long term solution.

I have another problem now. I was disassembling the housing because the fittings on the sides were corroded, and while one of them backed right out, the other one snapped off flush with the body. Not sure the best course of action here. I could look for a ~5/8ths screw extractor that would work to remove the rest of the threads, or some other solution.

Since you have an open hole to the back side, instead of an ez-out, which might break, I would just drill the bolt out.

[Praxiss454]

Originally Posted by kazoocruiser

Since you have an open hole to the back side, instead of an ez-out, which might break, I would just drill the bolt out.

The 3/4" threaded hose fitting is the thing that snapped off, not one of the 3/8" bolts. I think I'm going to have to file and chip it out.

[nsb29]

Originally Posted by nsb29

Put some heart on it first to burn the rust off then use your easy out

I will say it again heat it up with a torch after it cools down it will come out much easier some penetrating oil on it after it cools down will also help You already have a situation with stripped out holes for the bolts you could go on the parts bored I’m sure someone else out there has one for sale at a reasonable price solve both of your problems at the same time

[rpmerf]

https://www.harborfreight.com/5-piec...set-93822.html

Pipe extractors. Goes up to 3/4". I've used them before.

I usually do a couple cycles of heat it up, coat it in penetrating fluid, heat it up, soak it, heat it up, then try to pull it out. Hammering in the fitting should help knock the threads loose too.

[kdad]

Put out a 911 in the parts wanted section or keep an eye on the for sale section somebody will have one..

As others have said use heat and a penetrating oil when the part cools to get it broken free.

Use a Heli coil to repair the threads better than original "pay attention to the size of drill bit needed or buy as a set"

[andyh1956]

Threaded inserts use a Proprietary Tap & you will need the whole kit.
When you heat your broken fitting cool it off immediately with water. It's the RAPID expansion & contraction is what breaks the two pieces apart.

[Praxiss454]

Originally Posted by andyh1956

Threaded inserts use a Proprietary Tap & you will need the whole kit.

Yeah that's what the guy at NAPA told me as well.

I was able to get the hose fitting out by filing down some channels from the inside to weaken it, heating it, and then chiseling it out. Easy peasy!

Next, I'm trying to borrow a heli-coil kit to avoid having to buy it. But, is there any reason why it is a bad idea to tap to the next size thread, 7/16-14? There looks to be enough material that this would be fine.

[jdl71]

The heli coil for just one hole shouldn't be that expensive. I've bought them at napa before seems like there's 5 or so in the package with the tool. I should have a housing if you end up needing one.

[Praxiss454]

Originally Posted by jdl71

The heli coil for just one hole shouldn't be that expensive. I've bought them at napa before seems like there's 5 or so in the package with the tool. I should have a housing if you end up needing one.

Thanks, I was able to borrow a heli-coil tool from a buddy who had one, and he also had some extra inserts he didn't need. So, presuming I don't screw it up, I should be good to go.

If the heli-coil ends up being longer than the hole, should I just leave some of it sticking out the bottom or should I try to grind it off flush?

[jdl71]

I would cut or grind it off. As for your other question about moving up one size, if you have enough meat you should be fine. Will just need a bigger bolt in that hole.

[andyh1956]

Keep in mind that the larger 7/16" bolt you want to use will have a larger head on it & may cause interference with the thermostat cover and / or your tools.

[Praxiss454]

Thanks everyone for the replies. Gonna give the heli-coils a try as soon as I'm allowed back in the garage.

Do people usually paint the t-stat housing? I was thinking especially since the bottom is iron and the top is aluminum (had to replace it), it would look good painted.

[shp4man]

The retap for larger size method may work better with 8MM metric threads.

[Bimus]

If a replacement housing is needed I have a good one you can send me a pm
Kenny

[Praxiss454]

Thanks Bimus and others. I got some heli-coils in place and they look good! So I believe I'm all set here.