I own a 93 auto.
After I take her for a ride, when I pop the hood I can hear a bubbling noise. Yesterday when I started it, the coolant light came on

I filled the rad up this am and took it for another ride (about 15 miles), it ran strong and didn't overheat.

About an hour later I noticed a puddle of coolant under the front drivers side. Is this a bad AST? Any help would be appreciated.

Thanks

conrad

ps cya uday and qusay, they are now edday

 

Check all around the AST for cracks and check all the coolant lines. FYI, the coolant tank on the passenger side does have an over flow hole in it so coolant can come out if the level is too high. This happened to me before and scared the sh*t out of me.

 

Pressure test the coolant system.
And watch for pissing coolant out of the over flow tank on the passenger side.Look for tiny bubbles in the filler neck aswell.
If you over heated it you might have cooked your engine.

 

I sure hope not
I haven't had any coolant loss on the passenger side, just on the drivers.

conrad

Uday and Qusay are edday, yahoo!

 

AST or radiator core.. Possibly hoses.. bubbling could mean two things.. too much air in the system or running too hot.. pressure test first.. if everything there checks out try changing your rad and ast cap along with the thermostat....

 

Thanks for the advice all.

 

btt

 

I just bought a new AST. I will put the new cap on and see if that helps, before I install the entire AST.

C

 

bubbling is normal! That's why it's called the AST.(air seperator tank) it removes the air from the cooling system which is caused when coolant expands. If it's around the rear of the engine bay on the drivers side check your heater hose going from the engine to firewall. Ther are also 2 hoses that hook to your hrottlebody. (one from rear housing one from rats nest tubing. check for leaks there. PS: celebrating the death of ANY human being is a disgracefull act You SHOULD be ashamed of that comment!!! By celebrating you put yourself into the same warlord / terrorist catagory as those who you are SO happy have been killed. Please grow up and keep stupid immature comments like that to yourself! Good luck with your car though.

 

Please be carefull of the information you give out. Bubbling is NOT normal. A healthy cooling system maintains thermal eualibrium in the engine by keeping it at optimum operating temperature and removing sufficient thermal energy to prevent localized boiling which causes coolant to boil and enter gas phase. So if everything is working properly there should be no gas present in the system, therefor no bubbling.
That being said, there are 3 possiblities which could cause gas to be present in the cooling system.
1. The cooling system is insufficient. The RX-7 design took such drastic measures in reducing the weight of the car, they cut the cooling capacity down to a bare minimum. This puts the engine on the boarderline of overheating. There is even a section in the owners manual that describes what you need to do when the car overheats (don't see that section on most car's owners manual). That is the reason why there is an AST.
2. When coolan is replaced, the system was not properly purged of air. This is also where the AST can be helpful.
3. A leak in the cooling system, ruptured hose, loose connectiions, o-ring failiur etc. These are NOT what the AST is for.
Coolant expansion has nothing to do with air being produced. All materials have thermal expansion and contraction. Gas is formed only when the coolant boils.

 

In my opinion every RX-7 should have the stock AST replaced. I have met a few people who lost engines because the AST cracked. It is a relatively inexpensive way to fix one of the cars weak points.

 

Trexthe3rd- I completely Agree with you on the fact that air present is NOT normal in a HEALTHY cooling system. But I thought we were talking about an RX7 cooling system! Hahaha! Sorry for not being as specific as you were, I have not to this day seen a third gen with the AST not boil/bubble after being run. My coolant system is as new as it can get, no leaks, stays well below half on my gauge and yet it still bubbles . I consider it nothing to freak about unless you are loosing coolant. Totally replace the stock plastic POS.(Who's idea was it to make things that hold boiling fluids out of plastic?Arghhhhh!) Sorry again, didn't mean to give out incomplete info.

 

Like I was saying in the last post, weight savings. I honestly think the design engineers for the RX-7 traded too much reliability for the few oz of weight savings here and there.
I'm not going to name names, but I've created mods in the past that was mocked by this person. And his only supporting statement was that the Mazda engineers didn't do it. Sorry but IMHO RX-7 engineers screwed up in many places, the AST is just one of them.

 

What mods wre they ? direct me to a thread if possible. Any attempt to improve cooling should NOT be scoffed at. If it works, work it. Show me what your talking about, i'm interested. You couldn't be more correct about the maz. eng.'s!

 

Here is the original thread, it's been a while so the pictures were taken off.
belly pan thread

 

big island Steve,
Thanks for responding to my question and let me thank everyone else, as well.
BUT, when genocidal despots on par with Stalin, Hitler and Pol Pot are killed, I celebrate. I celebrate for the victims, their families, the world, etc.
Sorry, but that's the way I feel.

Conrad

 

Well, I installed the new AST cap and took her for a ride. The temp guage was noticeably lower and it ran fine. Also, it didn't dump coolant after I parked her.

Now to solve the warm start problem.

Conrad