Coolant leak from M-Tuned re-route
 

Have a leak at the back of my head, it's a BP4W. Basically I have a really slow drip/seep at the back of my head where the new housing connects to the head. We are going to pull and replace the gasket there, but I am wondering if I can just get one from the dealer, or if I need to use a specific one for the M-tuned re-route and where I can find it.

My mechanic was also asking if we could substitute in an o-ring but i don't see a groove or anywhere else for it to go.

I believe it's coming from where this piece attaches to the head, but not yet verified because I haven't pulled anything. It's one of a few things to get done by next track day and I don't want to pull it apart until I have a few ideas to avoid as much down-time as I can.

https://www.miataturbo.net/attachmen...ine=1459634161

You should be able to use a gasket from any parts store. I'm guessing it's the same size gasket as the front water neck, but I don't guarantee that as I've never had a mtuned reroute. I always use red gasket maker, then a real gasket, then another layer of red gasket maker to seal at the back of the head for reputed. Have always had leaks there if I did not do it what way.

just make sure it's a proper (I think composite) oem gasket, and not the paper junk the auto stores usually sell

Paper stuff is fine if you have two clean surfaces. Rtv is needed especially if you have a corroded surface, common these days.

yeah I've had to use rtv even with clean surfaces before, and the paper gaskets failed like half the time

make sure you remove ALL of the previous gasket material. Its hard to reach, but take your time, and don't use a glove, so you can really feel the surface. Be careful not to scratch the aluminum with the razor blade.

Also don't be shy with tightening those two bolts on the housing. Its hard to gauge torque using an allen wrench, just make sure it's tight.

I think I also put a very light/thin amount of sealant on the housing/gasket mating surface, that way the gasket stayed where it was supposed to be.

I've said it before and I'll say it again. Clean up the surfaces (light sanding, scotchbrite, etc.), and use Indian Head Shellac on both sides of the gasket. Never any leaks done that way. I'll never use anything else.

I've messed w/ my cooling system 3 times in the past half year and the last was my first time using a *subjectively* small amount of blk RTV. Thankfully, no leaks.

I was told to use a plastic scraper vs metal... as I never felt I had cleaned/prep the surface of the head enough, but it didn't do anything lol.

Best pic I could take of the rear outlet surface after I cleaned it. I never felt it was clean enough but gave up and hoped for the best.

https://www.miataturbo.net/attachmen...ine=1459702496