Hi fellas, using a coolant pressure tester, found a leak that looks like it comes from the "allen-type" bolt/freeze plug type thingy that's located on the fillerneck/thermostat housing. It's the bolt that's closest to the thermostat facing the firewall. It's kind of hard to see, but looks like the "trail" of coolant originates there.

Does anyone know why Mazda designed these types of "plugs" on the housing? There's 3 of them I think. And has anyone ever experienced these things leaking? Your feedback is greatly appreciated!

 

Those types of plugs are pretty common on most cars. Are you sure its not leaking form the coolant tem sensor or the fan switch?

 

Hello RX7will... thanks for the reply. I don't think it's leaking from either the coolant temp. sensor or the fan switch. The leak "looks" like it's coming from one of the bolts... the one that sits between the filler neck housing and the housing that actually holds the thermostat... so it's the one that faces the firewall. I don't think there's any sensors or switches there... it's hard to see because it's wedged in there pretty good. I could remove the filler neck housing for a better look, but that would defeat the purpose of the coolant pressure testor. Thanks for your advice tho... Plans are to replace thermostat/0-ring anyways to eliminate possiblities. Anyone else have info... pleeze! =D

 

Yep, I had a leaky one when I got my car. The previous owner did the good service of having the coolant system "professionally flushed" by a "guy he knew". Don't they all got a "guy they know"? Anyway, the topmost pipe plug was leaking and steaming because the most helpful "guy" had pulled it to help burp the system, by relieving imagined air spaces created behind the T-stat, which of course don't exist if we have the stock T-stat with the jiggle pin, which this did. So it leaked, and didn't hold pressure, and ran pretty hot when I first got it (coupled with a crumbling pressure style cap on the filler neck land, not a stock straight cap. Shoulda check the car cold!!!).

Now I have the shiney new engine mod

The plugs are there to seal holes drilled to allow machining of the complex path that leads from the filler neck down to the AST return nipple. Pull the plug and reseat it with a pipe sealant such as teflon tape or pipe dope. Don't smoke the pipe dope. It hurts. Ow.

Do this soon. Or prepare to play the shiney new engine game.

 

Spurvo... Hey.. thanx for all the info! As a matter of fact... gonna pull the thermostat either tomorrow or the next day to replace it anyways... and I do have teflon tape (somewhere in the garage). Thanks again... =)