What tool do I use to tighten the 2.5 inch hex on the M tuned thermostat housing?
 

I'm struggling through the M tuned coolant reroute...

I tried tightening the thermostat housing by hand, but I'm sure I didn't tighten enough.

I measured the hex or whatever you call it, and its 2.5 inches wide?! Any of the wide mouth adj. wrenches I found online only go up to 1.5 inches.

Do I just get two huge and expensive adjustable wrenches? A huge, deep socket and a huge adjustable wrench?

BTW I just purchased the CORRECT thermostat and seal that SHOULD have come with the kit... stant part #'s 13958 and 25270

Thanks

That or an adjustable wrench.

Wrap the hex in tape and put it in your bench vice with a set of non marring jaw covers. Don't clamp it down so hard that it deforms the housing, you are just trying to hold it and keep it from rotating.

When you install the rubber thermostat seal, use a small amount of grease on the surfaces. Don't slather it on, you just need enough so that is slides smoothly against the sealing faces on the housing when its tightened. You want grease not oil. I used the infamous Shin-Itsu window track grease because that's what I had lying around. If you don't do this, the aluminum binds on the rubber and you will never get the housing tight. It does not need to be angry monkey tight and you'll immediately be able to tell the difference between tightening it with grease and tightening it with a dry gasket. I think this is key to getting the housing to tighten correctly.

The threads don't need a sealer, but a little anti-sieze might not be a bad idea (I didn't do this.)

Joe's slip jaw wrench works, or you can use a rubber strap wrench, oil filter wrench, or even an adjustable drain wrench:
https://www.miataturbo.net/attachmen...ine=1440077458
Put some tape on the wrench if you are worried about it marring up the housing.

Anyway, hope some of that helps.

^ thanks! good tip about the grease..

I already bought two huge adjustable wrenches with a 4" jaw opening, so I'll just tighten the housings out of the vehicle