That's what I would do. It's a common size and should be readily available.

BTW, did you try using a slightly longer bolt, just in case there are some good threads a little deeper in the hole?

 

Tom A Excellent idea sometimes that’s all you need 1/4 deep more good threads just snug it with some locktight and a gasket sealer

 

Havn't tried that but doesn't sound like too bad of an idea. I guess my first experiment is using a longer bolt. I just need to figure out what size he used for that since it's an SAE bolt. I'm assuming it's a 5/16 if the factory size is an m8.

Makes me wonder if tapping an m8 hole to a 5/16 is part of the problem....

 

OK this sounds stupid but I observed that the factory holes were 5/16-18. The guy who tapped it out also used 5/16-18 BUT gave me an m8 bolt. WTF?

I have no idea how it went in fine the first time, but luckily the threads aren't too ****ed up. I just went to the hardware store and got another 5/16 bolt and it tightens down fine.

I also went and bought a new thermostat housing cause the old one was bitched up and some brush on gasket sealant. Hopefully this will serve me well.

 

Just give the gasket sealer a 1/2 day to dry real good and I think you will be ok.

The cooling system is not under a lot of pressur anyway

 

That actually didn't work, when I went to put the housing on (I test fitted it with the housing on) it still spun around. I used the longer bolt idea and it works. I got it just snug enough and it seems to hold a seal. I might of been able to go tighter but I was really nervous about stripping it more. That's why I used the gasket sealer. Like what was mentioned in the thread, let the sealant do the work.

Only problem now it finding the nut to hold my air filter on. D'oh! of all parts to lose...

 

If this still pops open on you redo it with only gasket sealer no gasket the good sealer is like a glue the gasket may become the weak link metal to metal with the Blue or Black RTV Sealant may work better and maybe rough up the surfaces just a little bit not too much so it grips the surfaces better. and clean all grease off

I used the red RTV on my Diff cover and removing it took some prying it was glued on good and tight

 

The size is M8 x1.25 course thread.mine measures just a hair over 1inch thread length. Head is 13mm and I found mine at the local hardware store.

 

disagree. though 13mm is "close enough" every "5.2" (I hate that designation, still a 318 cid to me) I have ever touched has taken a 1/2" socket on those bolts. youre looking at 5/16-18 threads. all fasteners on that engine except for the wire nuts on teh alternator, and the bolts that hold the lines to the AC compressor, are standard. NOT METRIC. I cant say the same for the fasteners on the body/ frame. I hate metric, and I hate even more, vehicles that are a mix match. We all have GM to thank for that clusterf#@k idea.
PLEASE don't bastardize that engine! That said I have had to Heli coil a few thermostat bolt holes on these engines over the years.

 

imine is a 2003 3rd gen 5 7 hemi. And it is absolutely a metric bolt. Just posting to help other hemi owners.