So I'm dumb and lost the upper thermostat housing bolt while working on my 99 Cherokee. Can't seem to find what size bolt I need to replace it with. Can anyone point me in the right direction?

 

I think the bottom bolt is the same thread. Just take that to the parts store and buy a new bolt that's the correct length

 

just did mine today and i can sort of confirm this from memory. the top one is just like 1/2"-3/4" longer

 

The catalog says they are 5/16-18 x .970"

You can get 1.00" length and grind about .030 off the end so they aren't too long.

 

Don't even do that. Just get a 1" bolt and use a couple washers. You don't want to screw up the threads in the block. (No pun intended)

 

Washers stacked under the head of a bolt looks red neck. If done carefully, grinding the end of a bolt is more professional looking.

 

Thanks guys. Headed to the store now.

 

wait wait wait.

why are they SAE threads?

 

Yea^

Meotch, be careful! I dropped a washer changing my T-stat. I looked carefully and couldn't find it. Instantly when I started it, my belt blew up. Big mess!

There is sort of a "maw" down below the T-stat where the belt goes around the crank pulley. My washer had fallen in there.

 

All internal threads on the 4.0 are SAE. With few exceptions, everything else on the Heep is Metric.

 

This is exactly what I did when I lost a bolt.
You can grind the bolt down without doing any damage to it. Just find the right size of nut to fit on the bolt and put the bolt. Then grind it down to the size you need. Then unscrew the nut and it will straighten out the threads. Of course you may need to touch up the very end with a small file. I have done this many time and never messed up the treads.

 

Probably on my site - www.kelleyswip.com/tech.html, follow the links.

On the 6-242, I know those screws are both threaded 5/16"-18. For the length, measure the thickness of the boss and add 5/16" to that - get that length. If it's between sizes, get the next one LONGER. May as well replace both while you're about it.

If you can, get brass, bronze, or stainless (CRES.) If you cannot, SAE5 is fine - just coat the screw with RTV before you put it in, to keep it from rusting again.