Apr 20, 2012 update to the Mazda MX-5 Miata project car

A Most Unfortunate Leak

We got a jug of distilled water from Wal-Mart to top off the radiator.
After topping off, we discovered a couple pinhole leaks in the water pump inlet pipe.
It's not a great solution, but it's better than nothing. Hey, we gotta get to work somehow.

It’s not completely leak-free, but it’s better.

You’ve seen those Looney Tunes cartoons where a leak springs on a pipe, and Daffy or Wile E. or some other ill-fated, animated animal plugs it with his hand. Then a leak springs elsewhere, then elsewhere again and again and again until the character is drowning and our 8-year-old selves are rolling in laughter.

We’re starting to feel the same way about our Miata’s cooling system, except we’re not laughing much this time. When we installed a new radiator cap that held proper pressure, one of our 20-year-old hoses burst a hole. So we ordered all new hoses from Mazda, flushed the system, and so overhauled the whole cooling system. Great!

Or so we thought.

Now we’ve discovered a couple of pinhole leaks in one of the cast metal pieces—the water pump inlet, to be precise. This piece is odd enough to only be available through Mazda, so we placed another order from Mazdaspeed Motorsports. They give discounts on OEM parts to all Mazda racers who sign up. This little guy isn’t cheap though: Even with the discount, it’s still a salty $76.

But we also needed to get back on the road in a jiffy. This is our daily driver, after all. We noticed the problem while we were visiting a friend who only had zip ties and duct tape at her disposal, so we fashioned a decent solution. It’s not completely leak-free, but it’s better, and we hope it’ll hold until our replacement parts arrive at the end of the week.

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View comments on the GRM forums
HappyAndy UltraDork
11/12/14 6:53 a.m.

JB weld.

Would that make a GRM trifecta of Macguver repairs? 1. Duct tape 2. Wire ties 3. JB weld

I used 2 of the 3 yesterday.

gearheadE30 New Reader
11/12/14 7:17 a.m.

JB weld for sure. A lot of older dirt bikes use aluminum or magnesium water pump housings that get very pitted and eventually leak like that, and since you can't buy parts anymore, it's pretty standard fare to goop it up and then grind it back to the right shape. Bonus: the pitting provides a nice rough surface for the JB weld to adhere to.

RossD PowerDork
11/12/14 7:22 a.m.

I believe you should be able to restore the old part with electrolysis. You just need to use an aluminum sacrificial part.

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