So, one day we have a puddle of coolant and the next we don't -- over and over.

We've replaced the AST with a Fighter's Garage unit, so the cap issue should be ruled out.

Can't see any visible leaks, but the leaks definitely come from the passenger side front or along the undertray on that side.

Yes, we do smell coolant. But I'm not sure if its from it leaking and burning off or if it's from a coolant seal leak.

So -- what are the best steps to isolate the problem?

From the searches it looks like:
1. check the presure with a tester
2. do the champagne test to see if its a seal

If we have a coolant seal issue, would it "leak" from underneath or just burn up in the chambers?

If it is a hose leak, is the smell from the burn off o coolant on the exterior of the engine or does smell indicate something else?

We do have some smoking at start, but it is short lived.

Thanks for any help on next steps.

 

If its the seal, sweet white smoke will come out of the exhaust at start up, and if its bad, it will continue for a considerable amount of time. Also, coolant would flow out of the coolant overflow tank all over the ground, leaving the system dry or with low coolant.

 

I'm guessing it's a simple leak in the tube that goes from the AST to the overflow bottle - the location is right for that. It could be the water pump, or some other hose leaking.

Other than blowing the coolant into (and out of) the overflow tank, a coolant seal leak will not cause a coolant smell near the engine. The sign of a coolant seal leak, as far as smelling coolant goes, is if you smell it out the exhaust.

I'd do the pressure test, unless you can search and find the source.

Recently, I've had a WP leak, and also the coolant-level sensor (this thread talks about it : https://www.rx7club.com/showthread.p...coolant+sensor ) split it's plastic threads and leaked. Both of those gave the coolant smell, and coolant traces on the rear of the undertray.

 

Dont go jumping to the forum because they will scare you. Run a pressure test and look for any coolant shooting out, check your turbo lines and you will see. Sometimes the TB line can get all cracked and so you should look back there too.

 

The hose that goes from the AST to the reserve tank -- do you have to remove the airbox to get to it? I know it has a plastic connector somewhere from the short reserve tank hose to the one from the AST, but I can't really see it from the top.

 

or its just the overflow bottle doing its job

 

That runs from the AST and then along the crossmember under the intercooler, so you do have to take some stuff off to see it. You may be able to get away with only taking off the undertray. You should be able to see most of it from the bottom, but some of it is under the air filter, etc.

Dave

 

If you're going to be doing work in your coolant system, I'd suggest replacing your thermostat while you're in there. I had a brand new one in mine, and it failed after 2000 miles. Since it wouldn't open, it was causing extreme pressure, which led to the rad cap opening and my coolant resevoir tank to overflow. It's about $11 from Ray Crowe.