AST Line popped off
 

Dumb situation, but my AST's top tube popped off earlier and it was spraying hot water / coolant (I was filling it up with distilled water) onto the engine bay. I think I mixed in too much distilled water when I filled it up because it didn't smell like coolant.

Car isn't leaking now or anything and the radiator fans are working, so I'm not sure if it was because I drove the car hard on the highway or what. It's winter and about 20 degrees out so I was surprised. Car started to overheat when it was parked, so I shut it off, let it cool down, and filled it up with coolant. AST fills up fine so it looks like it's not cracked either.

Here's a pic that explains it better and shows it after it'd cooled down a little. Top of the AST is venting steam.
Attachment 755910

Also, if it helps, the caps were switched and the spring relief cap was on the filler neck and the filler neck cap was on the AST, so I think this is why the hose blew off.


From looking at the cooling thread it seems like this should connect to the bottom of the overflow tank. I was just going to reconnect it and call it a day. Any other advice?

switch your caps.
The AST needs the spring cap and the other one needs the flat cap.

Ok, did that and no issues so far. Ordered new hoses too for the AST. And I just dropped my AST cap onto the radiator... fml.

*Consider getting an all-metal AST, the OEM ones have been known to fail with age and heat. Many vendors, Pettit Racing and others.
*Do NOT rely on the stock coolant temp gauge. It's not linear. If you don't already have one, install a decent aftermarket gauge ASAP.

Car came with a coolant gauge mounted but for some reason the electrical cable is disconnected. On my list of things to figure out.

Regarding the FD, EVERYTHING begins with cooling (IMO). All other modifications, especially performance mods, pale in importance until you have a solid cooling system. A lot of good reading in the 3rd. Gen. Section FAQ sticky, but this is a good start to get going....

https://www.rx7club.com/3rd-generati...thread-571088/

Ok, replaced all the AST lines and all seems well now. Also going to relocate the front license plate so it's not blocking the radiator. I don't know why I didn't think of that before.

Not sure what you have, but the stock front license plate bracket doesn't block air from the nose of the car.

Here's how it looks

Attachment 755785

I don't even think your bumper cover is stock. IIRC, on the 99+ bumper covers the license plate 'holder' was integrated into the cover itself.

You could simply using the lower plate holes instead of the upper plate holes. That's what MAZDA did.

Hmmmm.. not a bad idea. It'll be angled a bit, but it should work.

Maybe make a backing for it with a frame to stiffen and give it a more finished look.