Has anyone used the stock dual thermostat sucessfully as intended by Mazda?

I have it installed on mine and I don't have the rear T-Stat hooked up, I assume one of those solenoids operated the the valve there.

Also I am plannning on tapping a hole in the tstat housing and installing a petcock to bleed off air as that is the highest point on the engine. What do you guys think? Will this be usefull?

 

my friend ran a stock ECU car with the valve hooked up, so yes, and he's not the first...

mine had a bad thermostat actuator valve (and so did the other 3 i checked), so i just lopped it off, put a radiator cap in there and ran two stock FD thermostats, seems like it worked fine

 

I like that idea a lot, it is a great place for a radiator cap.

 

I dont think anyone like to use a 95ºC Thermostat as the rear thermostat is.
I have put in two ARC 75ºC Thermostats in mine and made a new housing.

 

That's a really nice set up. ..

 

You wouldn't happen to have a picture of that would you?

 

from sevenstock 5! cap adapter is just some moroso/summit racing part, its like $12. i used a stock GSL-SE radiator cap, cause thats what the 787B uses. upper hose is a GSL-SE. so its all stock parts, basically

 

I like that quite a bit. I turned my tstat 180 degrees too.

 

I ordered a weld on on radiator filler neck and a radiator cap with a temp gauge in it. Should be a nice way to tell if the thermostats are functioning properly.

Thanks for the inspiration.

 

Also that temp gauge cap is 20 lbs and the actual radiator cap is 16lbs so I am not going to worry about running a catch can to the 20 pounder.

 

Timely thread! Was just talking about the dual stats yesterday with MazMart.

As a non-techie guy, can you explain the location of the two t-stats? Where is the second one located? Any pics? I am sure it's been removed off my 3 rotor conversion but you never know. Have been chasing a water temp issue for a long time.

As far as I know I have one stat located right in the area you are discussing and it's an 180F unit.

 

Post a pic of the engine bay so we can see what you have going on. I started to look through your build thread but it is 103 pages!!!

 

^^ haha. very interesting thread i never knew 3 rotors had 2 t-stats.

I was aware that the rear rotor on the 13bs run warmer since the cool water picks up heat from front rotor before it gets to rear rotor. SO how did they fix this in the 3 rotors. COuld someone explain how this 2 t-stat system works.

 

Okay so here is a close up pic of my thermostat area during engine rebuild several years ago:



And a finished shot of the current state of the engine:



As you can see in the finished shot, the thermostat area changed a little. I have one (as far a as I know) 180f thermostat in the filler neck area and that's it.

So my question is, where is the location of the second 95 degree C thermostat on the stock 20B? I've never heard of this which makes it interesting. I'm assuming on my engine it's been removed but you never know. I am chasing a water temp. issue. My car lives at 90C which is fine but when I turn the AC on, it's more like 100C. And when I took the car to VIR last month I had to shut it down for the afternoon sessions as I saw 105-108C.

 

Yeah it looks like you have a single thermostat setup.

Here are some pics of the dual setup.

 

Also It looks like you have a few points where your system could lose pressure.

Check your radiator cap(s), petcocks and sensors. Just make sure nothing is leaking.

 

^That is pretty wild looking. Never knew there was a dual thermostat setup much less they were both in the same location. I thought there might be a hidden one somewhere. Learn something new everyday.

As for leaks, I'll give a good once over to ensure everything is in good shape. I am thinking of moving my PLX temp sensor over to the right side of the radiator filler as it now sits right next to the turbo and I've got to believe it best heat soaked in that location or at least is subject to a lot of extra heat.

 

So what is the purpose of this dual thermostat setup?
How does it work?

 

the second thermostat opens at 98C iirc, so my assumption is that it is a safety in case it were for start to over heat.

Flow was also controlled to the second thermostat via an ecu controlled solenoid and a diaphragm valve.

 

from the new model training book

 

yeah I can't read that.

 

sure you can, Tstat A in the rear, is an 82C (stock FD) thermostat, B is a 97c thermostat.

the valve ASSY is opened by the ECU.

the conditions for it being open are at the bottom

squiggly lines, AC off, 108C, space invaders, etc etc.

actually one of the parameters (there is another paragraph later in the book) is boost/load.

so basically you run around on the hot thermostat unless the car runs hot, or you step on it

 

That is wild. Learn something new everyday.

 

Nice explaination!

So here is my final product.





Thanks for the idea, I really like the way it turned out.

 

yeah that nice!