Hello everyone. I would like to get some advice from people who have had more experience with rotaries than I have (which is literally none lol). About a week ago, my coolant buzzer went off. After a few minutes of shutting the car off, I drove it a couple miles home without any buzzers or issues. Within the past week, the buzzer has gone off a couple times, but just for a few seconds here and there. I checked the overflow when the car was cool and there seemed to be plenty of coolant. This morning I drove a couple miles to school and after losing control of my car going around a corner (I think my 8 year old tires were too cold to grip the road), the buzzer went off again. After making sure there was nothing wrong with my car, I drove to my school's auto shop as it started to overheat. Coolant was overflowing out of the overflow tank. It also seemed apparent that there was some coolant leaking from somewhere else but I wasn't able to tell. I added water to the system and did a pressure test. The pressure didn't drop indicating that I don't have a leak, but it was still leaking? Next I plan on flushing the system. Do these symptoms sound like anything in specific? I don't have white smoke coming from my exhaust, so I am pretty sure my coolant jackets are fine. Any advice would be greatly appreciated. I apologize if I sound stupid as I am still learning, thank you!

 

First of all you can drop the idea that there's anything special or rotary specific about your cooling system...there is not.
The same maladies that might affect a piston engine can get you, mainly because most of the components are functionally the same.
Overheating is not good and you'll want to get this rectified right away.

Depending on the condition and history of your car, the easiest thing would be a cooling system "tune up".
This would include new hoses, thermostat, rad cap and coolant. Water pump may or may not need replacing.
Do not forget/ignore the two hoses that connect the heater core and the little ones under the intake that feed the thermowax/BAC.
Excluding the pump, those parts are about $200, depending on where you source them.

"The pressure didn't drop indicating that I don't have a leak, but it was still leaking?"
Half of this statement must not be true but it doesn't matter because the above recommendation will probably fix the issue.

 

 

Yes, I could.

After a while on the forum you'll notice a tendency, especially among newer members, to assume that the FC is some weirdly exotic beast when in fact, 95% of it is bog standard late 80's Japanese tech.
No need to look for oddball solutions, especially not before exhausting what should be standard troubleshooting practice.

 

If there was no pressure drop assume that there are no leaks. The low coolant light is activated by the coolant level sensor that it threaded into the top of the radiator. You will want to ensure that the sensor is in good working order and that the connector is free of corrosion or dirt. The next suggestion I have is that you may have air pockets in your cooling system causing the level sender to think that there is a drop in coolant as air passes by. Was the cooling system recently opened up for any reason? Overheating a rotary engine is extremely bad as the failure of a coolant seal is very likely. Indications of this are Alka Seltzer like bubbles flowing through the radiator, coolant consumption, and overheating due to the exhaust essentially boiling the coolant,

 

I don't recall ever assuming my car is "some weirdly exotic beast" when in fact, I never even indicated that. Last I checked, this forum was a place to get solutions from people with the same car as me. It is possible to give advice without being insulting.

 

I greatly appreciate this advice! I read about the coolant sensors readings being misleading on other threads. I will make sure to check for corrosion. Also, I don't believe the cooling system has been opened recently, but air bubbles or a clog is another thing I had in mind. Flushing the system and burping it should fix it if this is the issue, correct?

 

Definitely get a lisle spill free funnel set. Makes burping the system so much easier and cleaner.

 

How long did you have it under pressure for...? Depending on the leak, you may have some dripping of coolant from a breach but not really lose much pressure. You also have to consider the accuracy and sensitivity of some pressure testers isnt that great. I've rented some in the past that indicated no pressure loss, but I had some decent leaks, and it was only after flicking the gauge several times before it indicated a lower pressure reading..

Fill and burp the system. Replace your pressure cap, and see if the problem persists. If it does. Then a retaining wall for one of the coolant seals probably eroded and the engine is pressurizing the cooling system. I had an engine that passed a 15psi pressure test but still had a seal failure. More specifically, the outboard retaining wall failed.

 

 

Be sure to use a Mazda brand thermostat. There have been cases where aftermarket thermostats will lead to overheating. I have personally had this happen.