Howdy!
Ive owned my 87 Runner for about 2 months now, and im in the autoshop program in my high school. There appears to be a leak coming from the fill/check bolt on my transfer case, but according to my teacher and the parts guy at 'yota, the bolt looks to be oversized, like the threads got destroyed at some point and they had to put in a bigger bolt with new threads. Anyway it is leaky, so I tried to use some old gasket maker that has been sitting around the high school god knows how long, and it diddnt work at all. Most of the gasket maker dissapeared, possibly into the tcase, not sure if that is bad for it. What would be my best thing to do, buy a new can of gasket maker?

 

Drill and tap it for either a threaded insert such as keensert or the next size up standard thread. Gasket maker is for hacks or to get you through an emergency. Check mcmastercarr for keenserts.

 

the correct thread pitch was probably 1.25, not 1.5

i would scrub that case with some degreaser, looks like it is leaking from multiple locations

 

You're taking a CLASS in auto mechanics, but you come to YotaTech for advice?

Good choice!!
I don't KNOW the correct pitch, and 1.25 is a very common JIS thread pitch (so your Toyota is full of them), the largest STANDARD JIS fastener with 1.25 pitch is M12. https://www.boltdepot.com/fastener-i...ead-pitch.aspx And I think the fill fitting is larger than that. Which doesn't matter much to you, because you've got an M18 JIS bolt now. Which also suggests that you don't have enough material left to go to a still larger fastener or a thread insert.

Properly installed, the M18 bolt should work. Rather than ratty gasket maker, I'd pull out that bolt and try ONE (maybe two) layer of teflon tape. (If it's still leaking, more tape will only make it worse.)

And as dropzone suggests, first clean it up. Gravity is not your friend, and you could have a leak someplace far away and it will drip down to the lowest point.

 

The original drain plug and fill plug size on just about all vintage Toyota trannies, differentials and transfer cases is M18x1.5mm.

 

Okay, that's much better information than I supplied.

The photograph looks like the bolt used is not a flange bolt, but a regular head. The stock plug https://parts.lakelandtoyota.com/p/T...034118006.html indicates that it is for just about every year the 4runner was ever built.

You may have the right size (m18-1.5) bolt, but with the wrong head. Add a vanilla aluminum seal under the correct plug, and you may be in business.

 

I would recommend copper wire 14ga to make a washer out of if you need to or a few wraps of a smaller gauge. It is cast alum so don't get over on it.

 

good info

pretty sure this is the part number 90430-18008

for the transfer case plug gasket

most of the actual drain plugs is a 24 mm head

 

According to this dealer https://parts.lakelandtoyota.com/pro...rm=90430-18008 , that part number is for the gasket. I still think the plug the OP has is a just a hex-head bolt, and he needs a flange head (best with a gasket, too).

While these parts are still available from the dealer, if more convenient I might pick up a Dorman "universal" drain plug that is the correct diameter (use your calipers; don't just guess). If it fits (gently! -- if you happen to pick up an 11/16" by mistake you can really bung up the threads), then with a "universal" gasket you should be good.

 

you are correct, posting on my lunch breaks sometimes gets me rushed...

i like this hex head option
https://www.summitracing.com/parts/t...hoCqvIQAvD_BwE

i use those on diffentials since they don't get rounded off in the rocks