I have had this over heating problem that has been a slow progression towards worse every day. At first all I had to do when it began to reach a unusually high temperature was to floor it in third gear and it would resume normal operating temperatures. After a month of that it would just blow water out of the over flow tank, so I would stop and put more in. That went on for a few months. On my way to my bosses house she finally decided that it was time for attention. so I walked to the parts store and bought a new thermostat which I was sure was causing this problem. After I put it in, the temp just wouldn't come down. So I just took the thing out and it runs more than cool. This is just another half *** fix I know, but what would you recommend I do to fix this problem? The engine runs strong and it's a rebuild with 25k on it.

 

by getting an oem t.stat. it is not recomended to run with out one cause it can cause more problems. and there have been many stories of parts store t.stats not working right. so i says go to the nearest mazda dealer or an online one and get ur self an oem one.

 

no thermostat doesn't give the coolant enough time to pickup heat from the engine to dissipate it properly.

you have to have some restriction there or you are running hotter than you think you are.

 

Are you losing coolant?
Pull the spark plugs - do they come out really clean? They should be black and slightly sooty.
Eliminate that the engine is bad first...


-Ted

 

Sounds mor elike you are having a fan problem than a thermostat problem. I fyour thermostat was the issue then speeding up wouldnt do anything for you except increase the engine temp. All the thermo does is regulate the movement of coolant.


If you are speeding up and its getting cooler that means that coolant is moving. If coolant is moving then at the least your thermo is stuck open. The issue is that you arent getting enough air over the radiator. At low speeds that could be because your fan isnt turning. Have you checked to make sure its functioning?


Also, have you added to or flushed your coolant lately? Running without the thermostat isnt recommended because there is an optimum temp your engine operates at, and with coolant constantly flowing through the engine/radiator without control it will operate below that temp. At the very least you will see a decrease in fuel mileage.


Anti-freeze does just that, prevents freezing. water has a greater ability to absorb and release heat than anti-freeze does. In a climate that never sees freezing or near freezing temps there is little reason to run anti-freeze (except for some lubricating properties.) So even though Ted is a blow hard about people who dont know what they are talking about, he is right. You are wrong on that one.


BC

 

i know i might go on a different topic here... but the fan was mentioned so I think ill post a quick question.

if i were to get an e-fan i would need an fd alternator correct? Ive seen posts were its recommended to get an fd alternator for the use of an e-fan.

 

Its recommended because of amp draw... but.. not required. Plenty, if not MOST, people run their e-fans without upgrading their alt. Just find the lowest amp-draw to CFM ratio fan you can. Will probably be expensive.

 

do you have an underpan?? I know my car would hit near the half mark when i'd floor it in third gear, put the under tray on and my temps didn't budge, also i'd check to see if your seals are still good, water gushing from the overfill isn't good..I'd pressure test your system the pumps are expensive you might be able to get a car shop to do it for you, have you noticed any smoke upon start up that is a sign your seals might be done, although it's not %100 it's differently a step in the right direction in diagnosing your problem.

 

These are your two mistakes. Go to Mazda and buy a new thermostat.

 

first off go to mazda or buy a t-stat from me (I sell the oem nippon stats)
2nd water is the cooling property in the cooling system not anti-freeze. there is no such thig as "coolant" it is "anti-freeze" HOWEVER antifreeze in the water will help with lubrication, will inhibit rust, and also from what I have heard helps raise the boiling point of water, which is mistaken for cooling the engine whihc in fact it is not cooling the engine just making the water stand up to higher heats BEFORE boiling

Dave

 

This may also help (basic cooling system troubleshooting):

http://www.aaroncake.net/rx-7/cooling.htm

 

This is a commonly stated but totally false concept.
The thermostat is primarily a way to help the engine reach operating temp quicker- it's almost an ON/OFF switch.
Keeping coolant in the engine longer does not help it "pickup heat" nor does keeping it in the rad longer help it dissipate heat any better.

The thermostat's restriction (when fully open) is calculated during engine design to minimize cavitation- which not only creates hot spots but also speeds up the physical degradation of parts (look at an aluminum waterpump housing- all that pitting is mostly due to impact from air bubbles).

 

Completely wrong, the thermostat opens gradually starting at 180degF, reaching full flow at 200degF. This allows it to respond to the wildly varying heat loads and still maintain a relatively constant engine temp.

 

Yes, you can run it without a thermostat, but your temp will be cooler with an OEM thermostat (I think it distributes coolant more evenly or something). Stay away from auto-store thermostats. Running with no thermostat should only be a temporary solution. If the auto store thermostat isn't causing serious problems (i.e., just making your car run a little warm), I'd just leave it in until you can replace it. Get an OEM thermostat ASAP from any Mazda dealer, www.rx7.com or other such source. Never drive your car hard unless it is warmed up. This is true with or without a thermostat.

 

i had a similar problem. during highway driving my temp gauge would start to climb. with a push of the clutch and a jab to the gas it would suddenly drop back to normal operating temp. it also started to worsen. i found a small coolant leak in the hose from the heater core to the block. i replaced that hose and drained all the coolant and never had the problem again. i believe it could have been something with that leak or possible some crap that was in the coolant causing a clog.. then when i would rip on it it would break free. i would recomend draining the coolant & replacing, checking for leaks, and using a thermostat.

 

I recently bought an FC and noticed that it kept idling at 2k rpm and took a long time for the temp gauge to reach the actual temp of the engine, I called and ordered an oem thermostat from my local mazda dealer for $20, however im still searching for a better option, im looking for either brands or any recommended highflow thermostat that may or may not make the engine run better, thank you.

 

You ask a lot from a simple mechanical device.
Your cooling system needs the highest flow rate and most air flow at idle/low speed driving and that is precisely the opposite of the way the stock system works. The poor thermostat is working with two major components that are actively conspiring against it.

Swap the stock thermoclutch for a temp switch controlled efan (none of this cockpit Radio Shack toggle switch bullshit) and if really ambitious, an electric water pump as well.
Now you have a cooling system that responds to actual conditions and helps the thermostat stay stable and that may/may not make your engine run better.

 

Thanks for the Info, sounds like im better off leaving it without the t.stat, its just taking me back and forth from work at the moment and its my first rotary so I want to avoid damaging any components in the engine.

 

leaving it without a thermostat doesn't make it always open... it makes it always both opened and closed, aka, both coolant paths are open so coolant can bypass the radiator very easily which is the exact opposite of what you're trying to solve.

put a thermostat in it. you can run a colder one if you want. They're available.

 

also, posting a new thread might help. soon as i saw that the post was 10 years old i stopped reading.

 

The car needs a thermostat for the cooling system to work, otherwise, as eage8 noted, coolant flow can and does bypass the rad. However, putting in a cooler (than factory) t-stat is really a bandaid solution, that causes your car to run less efficiently. If it actually runs cooler, it can't run as efficiently as it should (since lower temps mean more combustion energy being absorbed by the cooling system instead of turning the engine), and will run rich, wasting fuel and contaminating the oil.

If the cooling system can't keep the car at the factory 180F/82C the stock t-stat opens at, it won't be able to keep it to a lower temp - although it will take the car longer to reach operating temperature due to the earlier opening, so if it can keep the temp lower than 82C under light loads, there's a small amount of extra buffer before the cooling system heats up to the point it reaches or surpasses 82C anyway. The real solution is to deal with whatever is keeping the cooling system from being able to shed enough heat, regardless of what thermostat is run - a bad rad (or undersized, if the car is modified for more power) , bad fan/fan clutch, slipping belts, or rust/scale buildup in the keg for example.

 

those principles apply to piston engines more than rotary engines, rotaries prefer cooler operating temps. efficiency? maybe you forgot what sort of engine these are. might not be such a problem in the great white north but down here even in mid winter we see temps in the 80's F regularly.

a high idle can mean air in the system or a stuck thermowax. the only way the thermostat would be at fault for a cold running vehicle is if it failed and stuck open or is missing.

 

Would switching the o2 sensor be a good way to start?

 

I think you're just smelling how a rx7 with no cats smells...

I'd you don't like the smell you should probably put a cat on it.

 

​​​​​​​I'll keep my straight pipe.... Just making sure it wasn't something else my dampener is all good, no leaks. And its idling way lower now, I still would like to switct my Tps but but it doesn't seem urgent