WonkoTheSane
WonkoTheSane SuperDork
6/14/19 12:36 p.m.

I'm resto-modding my 91 Miata, and part of that meant addressing the weeping gas tank.   When I tried to scrape off the undercoating-like-stuff on the outside of the tank in the wet spots it started pouring out, so I quickly drained the gas into my lawn mower containers.  It looks like there's no reason to not get a replacement tank.  They're not hard to find at a price low enough to make it not worth attempting a repair and this will get me an extra 1.7 gallons or so!


My only question is did they use anything special on the outside of it?  Is it just normal rubberized undercoating?   It looks like all of the replacements are just unfinished metal, including from Mazda.

02Pilot
02Pilot SuperDork
6/14/19 2:15 p.m.

The fact that it's rusting under whatever it is suggests you're better off without it.

GameboyRMH
GameboyRMH MegaDork
6/14/19 2:39 p.m.

Looks like rubberized undercoating, and being under a factory vehicle, you can be pretty sure that's what it is. If you want to try something else, maybe POR15 and then some tractor paint?

z31maniac
z31maniac MegaDork
6/14/19 2:47 p.m.
02Pilot said:

The fact that it's rusting under whatever it is suggests you're better off without it.

That's exactly my thought. I wouldn't take something that rusty for free.

Professor_Brap
Professor_Brap Dork
6/14/19 3:20 p.m.

Im like 95% sure its rubberized undercoating. I would personally use tractor paint instead. 

Keith Tanner
Keith Tanner MegaDork
6/14/19 3:23 p.m.
02Pilot said:

The fact that it's rusting under whatever it is suggests you're better off without it.

You caught the part where the tank is 28 years old, right? That's not a bad lifespan considering the environment the car has obviously endured.

Toebra
Toebra Dork
6/14/19 4:59 p.m.

Yeah, look at the stuff around it, rusty.

 

How about spray on bedliner?  Did the rocker covers of my 914 with that and it turned out pretty nice

Curtis
Curtis UltimaDork
6/15/19 9:31 a.m.

When undercoating gets compromised, it lets water behind it and holds it.  Undercoat is basically tape adhesive with latex.  I would consider something that actually bonds to metal, like paint.  I like Gameboy's suggestion.  POR15 and then a top coat with something.

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