I have had my 93 fd for about a year. I have not driven it much, engine has about 60k miles on it. About 10 months ago it overheated and shot out coolant everywhere and i thought i was screwed. Put a new thermostat on it and problem solved.
Last week it did the same thing. I discovered the coolant cap was no good and replaced it and the thermostat once more for giggles. (turned out it was clogged up) I let it run for 10mins after filling the coolant up and no problems. Then i found a video on the "champaign bubble" test. So the next day i took the cap off and started it cold. It would very slowly over flow and have a few bubbles in it, not much. After about 7 mins it is overflowing alot more, another minute and it is shooting out, breathing in and out. The car is still at normal temp and not overheating though. I have had my mechanical check for any external leaks, none are found. Took it for a 10 min drive and it acted perfect, thought nothing was wrong. Then it started heating up to the first line so I take it home and shut it off. Im thinking my coolant seals might be bad. However, there has never been any smoke or smell from my exhaust, which i researched is the sign.
So it overheats after 10mins of driving, no smoke or smell. As if this has anything to do with it, i find it odd this happens right after spending tons of work adding AC to the car. Is it worth putting Bars Leak into it?

Any ideas on what else there is to check? Any and every bit of help is appreciated.

 

What do you mean your thermostat was clogged up? Did you mix two different kinds of coolant?

 

***above all, don't put bars leak in your coolant system, that's a last resort if nothing fixes the problem and it really is the coolant seals****

1. If you're using anything other than your oem mazda thermostat and radiator cap, you're using the wrong parts.

Mazda parts are important , stant etc isnt going to cut it in my opinion.

2. Are you sure your electric fans are turning on at the right time, or at all ? if they're not working properly that's definitely your problem.

They use a thermoswitch that turns the fans on at a certain temperature, im not sure what temp but i do know that people replace them with a thermoswitch that engages at a lower temperature.

3. If you're overheating and there isn't smoke , your coolant seals are definitely not blown or at least completely blown.

If your car is drinking coolant , then overheating, then you're definitely having a coolant seal issue. If the seals were completely gone your car would be starting up sputtering (burning coolant out the combustion chamber), and smoking white smoke like a banshee out the exhaust.

It'd also lose coolant very fast, my old 88 rx7 would have all the coolant gone i put in the night before topping it off the next morning , from just sitting

 

The rubber seal on my coolant cap started tearing apart and clogged up the thermostat. I replaced it with a oem .9 bar spring cap. I also replaced the thermostat

 

I think there is an issure with my fans. They dont turn on when I turn my AC on. But it still overheats when im not using AC. They arent OEM fans and are probally not wired right and doing right speeds. I think I'll replace them. Any suggestions on a replacement??

Also, what it is doing is pushing water out of the overflow, after about 10mins of driving. It gets hot and pushes it out. There are small "champaign bubbles" if you let it idle with out the coolant cap off. Im going to order the FC thermoswitch to help which ever new fans I get. I dont know what else is making it over heat. It starts up perfectly fine though, even the remote start. Possibly the radiator or water pump??

 

Yes. One thing MAZDA got right on the FD was the OEM fan assembly/shroud. It worked. Without seeing your car, I can only speculate why a previous owner would have changed them. But if possible get a used fan assembly and return it to stock form.
Very unlikely it's due to the radiator or waterpump.
Are you able to post some pictures of your engine bay? A picture of your filler neck, AST, radiator/fan set-up etc? It sounds like it's been modified and seeing pictures might save alot of questions and time.

 

This is the only pic I have of my engine bay at the moment. This is how it was setup when I bought it. AST deleted, FC Filler neck. No AC
I just went through hell finding all of the AC parts I needed, and got it running. At the time I didnt even know what a AST was, since I didnt have one on there. So i thought, hell, I need to get that on there. Got an OEM AST and the next week I got this overheating problem.
I just recently deleted the AST and have it hooked back up the same way the pic shows, hoping it would stop overheating....it hasnt...
The fans I have in there are not stock/OEM. It was in a wreck from previous owner, and they obviously bought some cheap *** fans and didnt bother hooking them up right. They dont even kick on when you turn the AC on. So if I buy new fans and thermoswitch the car should stay cool, hopefully not overheat.
But...where the hell are the air bubbles coming from???

THANK YOU FOR ANY HELP OR THOUGHTS!

 

(dont know if this pic will be of any help)

 

It appears you have an Series 5 FC filler neck. That's fine...it's typically installed when deleting the AST. Make sure it has a . 9 bar SPRING cap. NOT a cap with just the un-sprung rubber seal but a SPRING loaded cap. If it's just a flat cap that could explain your overflow tank overflowing. Also make sure that the line running from that filler neck goes directly to the overflow bottle and that it isn't kicked and/or have anything pressing against it.
Of course there are other not-so-easy-to-fix reasons for that overflowing coolant tank but too early to draw conclusions for sure.

Don't worry about that champagne test just yet. It could be just a little air in the system...it's not definitive anyway.

The FC thermoswitch is NOT a silver bullet for overheating. All it does is trip the stock fans to activate at a threshold temp of ~ 95 C. instead of 108 C. It's a good mod, but only of benefit once you have stock fans working properly.

It appears all of the relays are still present that you will need for the stock fan assembly. Hopefully the previous owner went with the aftermarket set up only because he was cheap and left the stock wiring. There will be (IIRC) two electrical connectors for the stock fans, so look around for those just hanging loose somewhere. Do a member search for a guy name Fritz Flynn. Long time member and trusted source for use parts like the stock fan assembly. He might have one and if he does it will be priced fairly. If you can't PM him, check his profile for email or facebook. If not, let me know and I'll PM him for you.

 

It appears all of the relays are still present that you will need for the stock fan assembly. Hopefully the previous owner went with the aftermarket set up only because he was cheap and left the stock wiring. There will be (IIRC) two electrical connectors for the stock fans, so look around for those just hanging loose somewhere. Do a member search for a guy name Fritz Flynn. Long time member and trusted source for use parts like the stock fan assembly. He might have one and if he does it will be priced fairly. If you can't PM him, check his profile for email or facebook. If not, let me know and I'll PM him for you.[/QUOTE]

Yes I believe I have seen the two electrical connectors just hanging out down there together some where. What does that mean though? Is there a correct way to wire them? Or do I need a new setup?

 

The fan assembly ( i.e. the two fans, two motors and shroud) should bolt directly to the engine-side face of the radiator via 4 to 6 (can't recall for sure) 10mm bolts. The fan motors are pre-wired with two connectors that hopefully will plug directly into those two un-used connectors you now have. If they're the right ones, the proper way to re-connect them should be apparent.
And again...HOPEFULLY, the previous owner didn't jack with the wiring harness and once plugged-in/re-connected, everything works as it should. Only THEN would the FC Thermoswitch be of any benefit.

 

you need to make sure that your cap is sprung and not "unsprung" it will make sure u dont get overflow issues

 

so its been a while guys, i put off trying to get it fixed for a while. I took out the thermostat yesterday and drove it for 40 mins, no over heating or water coming out or anything. all is running good. wanted to get some feedback from yall to see if youve ever ran your 7 without a thermostat, and if I could encounter any problems driving without one.
Thanks again.

 

You'll just be over cooling the engine possibly making it take longer for the engine to fully warm up, because instead of the thermostat letting coolant from the radiator in at a given temperature it's flowing constantly.

rotary > pistons

 

Try bleeding the system if you havent already

 

is the radiator still in good shape?