Sigh....all of these coolant problems, and now this could be the worst



so here's what happened:

only owned since mid january

within the last two weeks:
flushed coolant, replaced radiator cap & body (previous owner had the 86-89 installed for some reason...AST is NOT eliminated). finally got all of the air bubbles out of the system---no gurgling. everything was fine


this weekend i was driving semi hard on the way to grab some food. i get to the restaurant, everythings fine, order my food, eat, etc.

when i walk back to my car in the parking lot, i notice a coolant puddle under my car, emptied from the overflow tank. I get in the car and turn the key to ON, no buzzer---start it, no buzzer...drive it home fine...except once I garage it, I pop the hood and hear that gurgling again...louder than before.


the next morning I check the level at the filler neck and it is still near the top..i pulsed the hose a few times and the level didnt really drop. After the cap was off for a few minutes, I look back and the level dropped to a lower(to the point where I couldnt see it in the neck)





anyone know whats going on? are my seals bad and not allowing the overflow to be recirculated?

the weird part is that i've driven it harder other times (like a day or two prior) and nothing like this happened. I don't get any white smoke, and its running fine otherwise...

 

Heres what I did... Buy the cap that has the red pull lever thing on top. I had one on my ast. Run the car, not too hard, watch the temps. Purge it. I never had problems after that.

Years later my tstat locked up and the car got HOT. Pulled over, burped the car and the temps dropped instantly, never had it overflow. I didnt drive after that though! If you are losing water, burping it will allow it to not spray you when you open the radiator cap.

Try it. Its what 5 bucks?

 

well, it sounds like the seals, i had a similar problem last year. Apparently what happens is that the coolant seals begin to go, and the rotors exhaust through the seals which pushes the coolant back through the system and into the overflow tank, where it leaks out. which creates coolant pockets through out the system, which is why its gurgling so loud.

I was told that coolant leak from the overflow tank is almost a sure sign of coolant seal failure.

i hope thats not the case on your car, but its sounding extremely similar to what happened with my engine.

 

He has to look for the tell tale champagne bubbles in the coolant in the radiator cap.

Air in the system will cause overflow also. Just start with the cheap and easy. Then prepare for the scary stuff. Mine overflowed twice when I first got it. Bought my purge cap, 4 yrs later still no overflow.

 

The champagne test is unreliable. I would recommend that you get a pressure test instead.

 

pressure test will test for leaks right? will that tell me about the seal(s) as well?

 

Yes.

 

Yep, that gurgling sound-it's the coolant seals. I had to rebuild.

 

Before you panic, check for leaks in the coolant recovery system:
1. leaking hose to coolant recovery tank (coolant on the ground, or air sucked back into engine instead of coolant)
2. leaking AST cap (spring-loaded seal) allowing coolant to boil due to not enough pressure and overflow

 

For some unknown reason, some of our cars coolant recovery systems don't work right. The system won't allow the coolant to completely return, and fill the AST after cool down. I have seen several FD's that would overflow coolant until the system "equalized" at a point where the AST remained about 1/2 full, and never dropped any further. I suggest that you let your system "equalize" itself. As long as you don't get a low coolant buzzer, it should be ok to let the system work itself out. Just keep an eye on it to make sure it doesn't get too low.

 

thanks for all the input guys.

refilled as much coolant as i could,
took the car out last night, warmed it up and had a spirited drive. got home, garaged it...in the morning, nothing overflowing from tank...


maybe i do just have a couple small leaks---any suggestions on a good pressure tester to use? (ive never done it before)

 

how exactly do you burp or purge the system?

 

I bought mine from sears, but you don't need to buy one. Just take your car to a pep boys, or something. Should be a quick in and out.


The easiest way is with a lisle funnel. You can get one here: http://www.absolutehome.com/home/1/4...ee-funnel.html


It's a great tool to have around.

 

i did some more reading...


i want to get that hydrocarbon test done (where they test your cooling system for exhaust gasses)--can any smog shop do it?

 

did you put this cap on the AST or on the filler neck,or did you put it on both?

 

hey tedder can you please answer

 

he said he put an AST cap on the filler neck


anyone know the type of shop i need to go to for a coolant hydrocarbon test??

 

As I understand it, you should be able to get this test done at most shops.


One more thing: Make sure that your caps are the right kind, and in the right places. (It sounds as if you have the wrong cap on the filler neck.) Read through this thread for more info:

https://www.rx7club.com/showthread.p...iller+neck+cap

Post back after you get the test done.

 

will do! and no, I dont have an AST cap on my filler neck---thats what TEDDER1 did on his.

speaking of which---i never replaced my AST cap because i assumed it was in good condition--the AST is pretty new, steel one from petit that was put on the car right before i bought it.....but i read in a post that they often come with defective or crappy caps.

can I order an AST cap from mazda to use on the petit AST? or does it require a special petit type?

 

I believe you need the Stant domestic radiator cap @13psi. Should be easy enough to find at an autozone, or advance auto.

 

To quote myself:

Buy the cap that has the red pull lever thing on top. I had one on my AST.

Sorry havent checked the site in a few... BTW I had a pettit AST... Stock radiator also.