I have the cosmo 13b-re engine and I want to know what the normal or max operating temp is (according to water temp) before things start to go like water seals... My car will run near 190 ish on the freeway and if it ever hits 195 I shut the car off and cool it for a while. What is my range of water temp I should get worried at?

 

240 °F is the temperature when you should start to be very concerned... Hopefully you would have shut it off around 230+ °F, though. You're perfectly fine at 195 °F. My car ran 195-201 °F before I got myself a "yoohoo belt".

 

You can replace your thermostat with a lower temperature unit. Normal operating temp for most cars is somewhere in the close neighborhood of 185 degrees.
You can buy an assortment of different temp t-stats. I run a 165 degree in my bridgeport for extra measure. Never run your car without a t-stat. The flow of water needs to stop so the water can absorb the heat from the metal before the t-stat opens and lets the water flow into the radiator.

 

There's no reason to replace the thermostat with a lower temp. Doing so will accomplish nothing but lowering fuel economy and causing carbon build up

Fix the cooling issue. If the car is running hotter on the freeway, then you have a radiator airflow or water flow issue. Rad clogged? Missing the underbody tray?

 

Yep, changing the T-stat won't make the car run any cooler.

I'd even start from scratch....drain the coolant and flush. While it's draining, visually check the face of the radiator, especially the area that might be behind the A/C condensor, and make sure it's clean. I'm always surprised when this is overlooked. Then refill with as much DISTILLED water to coolant as you can safely get away with in your climate while 'burping' the system to get the air out. And as Mr. Cake suggested make sure ducting is all in place and see what you get.

 

lowering the operating temp by way of a t-stat does not dramatically lower your fuel mileage. It's still within "operating temp". People that stat this usually have no experience with it. Yes a colder engine uses more fuel, but we're talking a colder engine. 165 degrees is still within operating temp. The reduction in fuel economy is unnoticeable it's so small. we're talking a fraction of a mile less per gallon.

Yes there is another underlying issue to the reason the car may run slightly warmer but I'm sure we're not aware of all the variables this car and driver experience either.

Good point to ask about the underbody tray. I often forget about those myself,, they do make a noticeable difference.

 

^Regardless, unless it's really cold outside, a T-stat with a lower opening threshold has as much to do with the car running cooler as adding air to the right rear tire. It would not help with the OP's problem.
And 165 F. (74 C.) is well below the optimum temp for a rotary IMO.

 

you know what I did fail to make a point. a lower temp t stat is only to be used when you have a properly working cooling system. it in no way helps or works as a quick fix or band aid to an improperly functioning cooling system.

but a lower temp tstat is critical if you're running your car hard as if you go to the canyons and "really drive hard" or if you have a turbo setup especially a bigger than stock turbo. if you don't know this than you haven't built cars/raced cars.

A colder tstat also does wonders to remedy the overheating Bridgeport in stop and go traffic. you need to let the hot water out of the block and into the radiator before it gets to a temp thats harder to manage and cool. it's really simple. I don't know why it's even a subject of discussion. just goes to show the difference between experienced builders and forum learn-ned folk. hahaha
I learned lots of my stuff from old school builders and none of its ever led me in the wrong direction. It's tested and tried in my book, not just forum folklore.

but just like forums go, there's always opposition, always someone that actually know more and can teach and always more that think they know more but really know far less.

nobody is ever on the same page.
I'm outta here. have fun arguing.

 

And I'm probably older than your buddies.

 

Post #4 says it..
better air flow to the rad and ducting can cure the temp problem.
BLUE..ya wanna go To the Senior's home this Friday with me?..they are having Date night..lol!
We can score some chicks!
........

 

This is the New Member Tech section, so remember, if you give a suggestion or advice that doesn't really jive, then it will be addressed.

Normally at 165 degrees, I'm adding about 10% more fuel than at operating temp. 165F is 20F lower than operating temp. 10% more fuel over the long term adds up to a lot though time. Plus there are the other issues. Mazda designed clearances for an operating temp of 84 degrees. When running the engine cooler, did you adjust clearances accordingly? Did you adjust oil weight? Move spark plug heat range? What about emissions equipment? The cats aren't going to stand the vehicle running constantly in cold start.

It doesn't matter what the variables are. The solution is never to install a lower temperature thermostat. If the cooling system is unable to cope with the amount of heat produced at operating temperature, then there is something wrong or it is undersized.

If you have a properly working cooling system, then there is no need for a lower temperature thermostat.


A properly designed cooling system is critical if you're running your car hard as if you go to the canyons and really drive hard" or if you have a turbo setup especially bigger than the stock turbo.

Quite curious then that I have no issues with overheating in my bridgeported, GT40R, 500 RWHP daily driver 2nd gen, using the stock 84C thermostat. All it takes is an undertray, Fluidyne rad, and an e-fan activated at 90 degrees. Not really difficult to achieve.

I think you just made your point about "experienced builders". Most of the "experienced builders" I know still believe old myths like thermostats cause overheating, carburetors make more power than fuel injection, and bridgeports are somehow hard to drive.

As I pointed out, it's a subject of discussion because your advice is contradictory to what should be given in the New User Tech forum. Then again, feel free to post your same advice in the race car forum, single turbo section, or other subforum of your choice and see what the result is.

If you have to stop your coolant from heating up to operating temp to prevent overheating, your cooling system is undersized or you have another issue. There's really no debate.

If your cold school builder buddies are so knowledgeable, get them on the forum! They can help out and would be an asset to the community!

 

Well done A. C.