Ok I got this car like 2 weeks ago and when I first got the car the temp gauge would go just alittle above "C", which im probably thinking the temp sensor was messed up and wasnt reading the right temp, Ok so now Ive installed a duralast thermostat and a 14" Electric Fan, I also converted r12 to r134 and with the a/c on the car overheats( I live in pahrump near las vegas and the car overheated while it was 112 outside), besides from that after I installed the electric fan, my temp gauge now rises between "C" and "H" w/o the A/C on, I know that MOST cars temp gauge will rise half way, so is my temp normal for this car and am i just being to over cautious?

Other note, I noticed i have a leak at the thermostat housing, which I believe is drawing air into the cooling system.
I plan on installing a new raditor anyways and im buying a failsafe thermo tomorrow
Can anyone out there help me figure out whats going on, Also the car does not blow white smoke. Thanks for any help

 

You need to fix the leak first.
What is the CFM rating of the electric fan and what temperature T-stat are you running?

The 1/2 reading on the temp gauge without the A/C on in that outside ambient temperature is normal.

The radiator may be partially blocked also causing the overheat situation with the A/C on.

 

if by failsafe thermo you mean awesome t-stat buy only mazda.

 

List the brand, size, part number and cfm rating of the e-fan. Many of them don't pull enough cfm for a rotary. You need one that pulls around 2500 cfm. Honestly, the stock fan works quite well. The normal position for the temp gauge is just a little past the bar by the C. When mine gets up to the mid point, I start looking for faults in the cooling system cause that is a higher than normal reading unless stuck in stop and go traffic on a hot day. Once the gauge moves past the halfway mark, I start looking for a place to pull over and let the engine cool down. On our gauges, it takes very little for the needle to move from the halfway point to hot and when that happens, it's often too late and the engine has overheated.

My suggestion is to reinstall the stock fan, fix the leak in the thermostat housing and order an oem thermostat, from Mazda, Racing Beat, Mazdatrix, etc.. I have yet to find an aftermarket thermosat that works as well as the oem one.

What is this failsafe thermostat you're thinking of buying, details please.

 

You need an OEM tstat, installed properly with the jiggle stick up.

Re-installl the factory fan. If you have a compelling need to replace something then replace the radiator: and a stock radiator should be OK.

Check the front of the water pump for stains near the "weep hole". I had a pump fail after only 6 months because the mechanic over-tightened the alternator belt and the bushing failed prematurely from the excess tension.

 

The stock temp gauge blows so definatly like all these guys are saying, if it hits half way or more your getting into trouble area. Mine sits solid at about 1/4 the way along, and I just put in an aftermarket water temp gauge with it's own sensor and it reads 160-170F (73-78C). Anything over 190-200F is getting too high IMO.

 

Be very careful with the cooling system because it can have such a big effect on the rotary engine. Since the engine is so light, has such a small mass, the temp will rise faster and higher than with a heavier engine. That's why I avoid innovations, like electric fans, off-brand thermostats and chancy water pumps. Also, I've found that the radiators deteriorate at around 100k miles: I've replaced radiators on all my cars.

The best thing you can do on the 12A is replace the heater hose that passes under the beehive because oil drippings deteriorate the hose and it will suddenly burst, either leaving you stranded, OR, more likely you'll drive it back home and burn the internal water seal orings. Not good.

 

Tomorrow im gonna reinstall my stock fan, and fix the thermostat housing leak, im also gonna go buy the failsafe thermostat aswell, I believe is states its a Original equipment temperature 180 part no.7228-180 from autozone
also the e-fan is by TorqFlo 14" doesnt list anything else part no. is 733690 bought it at autozone
And Failsafe is a thermostat and it claims it never fails thats why they name it that, ive used them before and they work great,

 

Some new thermos don't include the gasket....a definite must. The surface must also be completely free from old gasket. Check the radiator to make sure it is clean and not full of crap. Reflush the entire system too!

The only e-fan I've ever run was a 16"....your fan is probably too small. Is it shrouded? Is the fan on a thermostat or on all the time.

While you're at it...might as well do the water pump, just to be on the safe side.

What's the daily temp where you are the last few days? Here in Burbank, Ca its been at least 90....my temp gauge rises about 1/4" past the C. Even when it was 100 a month ago I the temp stayed constant.

 

Why is that "Failsafe" tstat 'great'? Is it designed for a rotary? Does it have the jiggle stick required by a rotary? Why do you want to gamble your engine on a $10 item you know nothing about?

 

1. Best to get OEM t-stat. The aftermarket (even if they say are OEM replacement) will either be missing the jiggle pin or the lower portion of the t-stat for bypass type systems. The bypass thing is most important as you can lose 20-30% cooling capacity without it.

2. The 'Failsafe' t-stats..it is not that they don't fail, but the fail in the open position when they do (good thing). I would still stick with a Mazda t-stat, though

3. People saying that their temp is 160-170 are obviously are running a 160F t-stat (not OEM). The OEM is a 180F unit. Pump outlet temperatures will be just above this (185 or so) unless it is very hot and/or A/C on.

4. For the stock temp gauge, I would say it is consistent (would track an aftermarket okay), but I would not say it is accurate from car to car. Some cars run just above the 1st mark, some are like 1/4, some like 1/3, some 1/2. For instance, my car was more like 1/3. I cleaned the terminals in the cluster and now it shows closer to 1/2. However, using a megasquirt and the thermosensor in the back of the waterpump, my outlet temps are spot on (about 182-184). Age, corrosision/crap on terminals, etc. can cause a lot of variation from car-to-car with the stock gauge. If the stock gauge is okay, the 1st mark past 'C' is 104.1 Ohm, the mark before the 'H' is 21.1 Ohm. The FSM doesn't spec the middle mark. However, when the car is warm (176 F), the sender should be at 53.5 Ohm. This whould put the needle well above the 1st mark, but hard to say exactly as the scale is not linear. If someone tested their meter and found it to match with the FSM, they could then attach a 53.4 Ohm resistor and see where it reads. Operation will then be just above this point (180 or so F versus the 176F).

5. Either use the stock fan (w/ good clutch) or an e-fan with a very high output. There are only a few aftermarket e-fans that flow enough to keep our engines cool.

 

I bought a little Infra-red remote Temp Sensor that I've found useful. I just point the red laser pointer at various parts of the engine and cooling system and read-out the temperature. Helps to find hot spots, if any.

When not using it on the car you can use it in the kitchen to get the pan temp exactly right before frying an egg. Good for controlling sautees, too. Or for judging when to pull a turkey from the oven.

Cost about $30 at Harborfreight.

 

Don't argue about the thermostat. On my fresh rebuild, I installed an Autozone oem replacement one and spent a very cold 600 miles driving to Denver for Christmas. Engine temp never got above 155 by my aftermarket Autometer gauge. When I got back home, I installed the only used Mazda oem thermostat that I had. Engine temp went to and held at a steady 180*. That was nearly 3 years ago and I'll never use anything but an oem thermostat, even if the damn things are $25 from the dealer and I have to wait 3 days to order them.

 

ok im not trying to fight this but and your all right about OEM parts however I dont understand why parts would be listed under 81 mazda rx7 at any autopart store then u take it home and it doesnt work, Why is my question, Why would it be lsited and not work????
Anyways I still have the old thermostat I took out and I believe its the OEM stat so ill clean that up get a new thermostat housing gasket and put it all back to stock. Thanks all for ur advise

BTW its only gone past the 1/2 mark I believe three times and all three times ive shut her down, If I fix it now am I still safe or is it to late??? Is the Motor KIA

 

When you replace the tstat cover be sure to use something like anti-sieze or a good grease on those threads to (try to) reduce bolt breakage. Or, you might consider getting replacement bolts in Stainless from a good hardware store. I was about to do that and decided against stainless because I'd just put in a heli-coil and I dreaded having to drill out stainless in some future repair.

 

The aftermarket fit and may work okay. It depends. Some are similar to OEM and some aren't even close. This is just one of those parts where there is no subsitute for OEM. So you can save a few dollars now and use aftermarket, but you risk the engine in the process. Bad deal IMO.

As for the engine, can't really say. It depends more on how badly it was overheated and for how long. If overheated badly, the o-rings will get fried and the housings can warp. This results in coolant getting into the combustion chamber (like a blown head gasket on a pison engine). It can then be hard to start and will blow white smoke that smells sweet. Another possibility is that the combustion gases get into the coolant system and push water into the rad overfill bottle. The radiator will show "champagne bubble" while the car is running. Just depends where the breach of the coolant system occurs. Either one of these = rebuild. Sometimes if the car has not been overheated, you can still get the white smoke. This can be bad o-rings in the intake (the 12As circulate coolant through the intake) that allows coolant to get in the air/fuel mixture.

 

well maybe im lucky then cause it doesnt smoke and it doesnt bubble while the car is on the ONLY bubble that I see in at the very top of the reserve where they put a pin hole on the cap but the reserve doesnt over flow.
Beside from that I re installed the stock thermostat and put back on the fan its now stays strong right above "C" like 1/4 and havent moved I didnt try the a/c yet so I dont know. And when it did overheat it was only alittle above 1/2 for like a min and I shut it off.

And also the car is hard to start sometimes I have to put the pedal all the way down and keep it there until it starts and it blows out black smoke and I also noticed the it wasnt water leaking from the thermostat housing it was gas from the fuel lines just above the thermostat housing and with autolite spark plugs and a fuel leak is why it probably has a hard time starting, I have NGK plugs coming tomorrow

 

What kind of Autolite plugs? What kind of NGK plugs?

 

ps rx-7 rage,
a good ghetto way to counter check the temperature guage if reads high is to splash a few water droplets on the engine block. Engine temperature isn't supposed to be above 190 F.

So if those water droplets sizzle, you then you are overheating, and you are not being >>>over cautious<<<

 

If you are wanting to keep the e-fan, make sure you get a proper fan switch. The stock TII versions work well....tap it into the thermo housing after the t-stat.

Under extreme conditions, I've seen my water temps hit 215-220, under constant load, but it drops immediately when I get off it. Oil temps have seen 240. Motor is 4 years old, daily driven for 3 years, over 100 psi front and rear comp., run to 9000 occasionally, usually 8500.

To keep you rotor alive, just check water and oil systems weekly.

 

ok I know this thread is getting old but the car I guess after driving to vegas to a test run the temp go's half way between c and h, however, Its 112 outside not to mention I have like a 5 mile up hill (mountain) to drive up and then once over the mountain it cools right down.
Speedracer, When the temp is inbeteen 1/4 and 1/2 I open the hood and I dont hear it boiling and the reserve isnt hot, infact ive put my hand on the rad cap well hot and its not even hot enough to burn me I mean dont get me wrong the suckers hot but not extreme.
Anyways I took the rad out last night and flushed it out and a piece of rubber and looks like a piece of gasket came out, Im thinking when I changed the thremostat and scrapped away the old gasket a piece may have feel in the engine block leading into the rad, so I still dont know yet cause my wife is suppose to bring me home some 50/50 antifreeze and shes still not home, so ill update after. Thanks again all for your help

 

IIRC, 50/50 coolant mix is optimal for cooling.

 

im pretty sure 90 water 10 glycol is optimum since that is the mix that race cars use. Most often use 100 water in their race cars.

 

I'd just do 50/50. We don't need people freezing their motors up.

 

UPDATE, the 90%/10 mixture reserver I didnt even know the car had, I just found the reserve the other day, I thought I only had to fill the rad and rad reserver, however are you guys talking about the Sub Zero reserve and is that ONLY for winter??? Im lost now because this car has 3 spots to fill coolant im confused