Hello, I overheated today after a short drive after noticing my Heat/Radiator light turned on during start up and stayed on.

The rad, stays Cold and the engine block gets quite hot, I assume It's my thermostat staying closed, as I have ZERO coolant leaks.

I don't think see how the waterpump would break.

I also checked a plug and only white spot is mirco specs on the inner tips, that i've seen many times on many cars.

Too be quite honest their really is no coolant dripping down from the pump nore signs of lost coolant.


Has anyone here had both lights come on and simply changed the thermostat with success.

 

generally the thermostat is the first thing to look at, as its easy. although with both (?) lights on, you are missing coolant, and should be looking for leaks too.

 

Exactly which two lights came on?

 

If the belts are off, you can wiggle the water pump pulley to see if there is freeplay.

 

its not always about freeplay in the pulley. its about the vanes inside having too much clearance from the housing now allowing it to make pressure.


i refuse to test thermostats. they are 10 dollars total. if you have the old one out, put a new one in. you arent losing any money to speak of and you already have it apart. and yah yah, people say you need to test them. whens the last time you saw a DOA thermostat from a reputable company? exactly...i havent seen one either in 15 years of doing this.

they are pretty straight forward on the rx7's so give it a shot.

 

$10??? For a mazda OEM? I paid $35 for mine

 

Non OEM replacement t stats are $10

 

I need to test mine they're only sold at one place for $90.00...

I'm aware of this massive rip off, that's napa for you anywho, plugs are $28 not including taxes each!

NO LEAKS! Iv'e had coolant leaks before but it's dry as a bone, and no fluid anywhere.

Feels like the coolant is shaking around but not passing though to the block when it gets to operating temperatures.



Update: only had like 5L with an upgraded RAD... Ill do a flush replace hoses: SQUEEZE/burb.

Quote:

If the belts are off, you can wiggle the water pump pulley to see if there is freeplay.

I have heard of this but never seen it practiced before, but it's 100% true, should be 0.5% or less of play so ill test that bad boy as well.

 

And there have been many threads proven that non OEM thermostats do not work in our 7's

 

If you are in the USA, I would order form mazdatrix

 

How do you define "overheating"?

There is no such light on American cars. Do you have a picture?

What "both" lights?

See if Ray ships to Canada.

Ray Crowe
Malloy Mazda
(703) 490-5296
HMKParts@aol.com

Don't forget to replace the two O-rings under the oil filter pedestal. Broken O-rings cause oil to leak onto the lower radiator hose, which may develop a pinhole leak.

 

I think you mean "heater core" hose, not "lower radiator" hose.

 

UPDATE:

I removed my belts and due to my JDM S5, I was able to remove waterpump neck easily and thermostat.


SO can you guys help me confirm or conclude this: with these details
Upon: hand turning the water pump with the thermostat out and water pump free, I check for play: their was none I was able to see coolant get pulled into, once stopping it flowed back up and settled, I gave it a quick turn and it slashed me.

Am I right to believe that this concludes my pump works: no free play, no noise from hand turning and pulls coolant in at top of housing.

The thermostat:

Dropped it in boiling water for one minute 100-110C it opened up only 5-15% 1-2mm.

I'm assuming it's worn out and needs replacing.

Toss me a quick one! I'm hoping I am right!
The HEAT light on my Dash is related to block sensor on a JDM S5 engine: that is still on as I havn't replaced my thermostat and let it run more then 1minute to get to coolant flowing with the thermostat open.

 

It's the thermostat.

 

Yes, thanks, I mean the lower heater hose.

The thermostat removal is pretty much the same on all models, so what do you mean by this? Are you sure that you have Mazda parts?

This is not the proper procedure for North American models. Are you using a foreign manual for guidance?

That sounds like an aftermarket light. You also mentioned a second light earlier. Do you have a picture? You can't troubleshoot the car until you find out what the light actually means.

 

There is an over heat/exhaust system light. Is this what you are talking about?

 

HEAT Light is the only light on as of now, It is called HEAT as it is from a RHD car which my car is as I stated 100x as a JDM car not a USDM FC3S.

The Idiot cluster on a 1987 to 1992 FC3S from japan is not at all similar to the USDM one you keep referring to.

Yes you are right, picture of a muffler with heat lines coming off of it, aftermarket exhaust on a FC3S sensor is toast, for obvious reasons.



Any reason why no one suggest testing the water pump physically if it worked as all S4-5 13b motors have similar housing that can be visually inspected for coolant being pumped?

I don't see how doing this procedure could cause any issues as your simply testing, by turning a "fan" if you will? I see no ill effects of this procedure.

Just buying a thermostat unless something about my testing was horribly unadvised?

 

The sensor for that light would have a ground on it to turn the warning light on. Usually it has voltage on it which would prevent the light from illuminating.

 

Checked it out, seeming it was crimped and or "jumped", to complete the connection.
as for the current one I'm running is not, allowing idle adjustment via (heated) pressure release.

All is good in the hood, minus me pulling up the carpet to swap with my old crimped Heat warning sensor. via passenger seat.

As for the water pump it's on it's way out as the thermostat was but it seems to pull, and their is 0 side effects from manually cranking a mechanical part that has no connections to internals.


I guess that's one way to test if it's working, minus the fact not everyone has a lot of accessories deleted.


As for a side note, is their even a replacement sensor for this??? or do we assume aftermarket exhausts do not follow same piping routing: leading to the sensor being affected in a way that heat will set the warning light off?

 

I know everyone say's non OEM thermostats don't work but I disagree. I have had a Stant thermostat in my car for 3 years. Still working great. Temps monitored by and autometer gauge not the stock gauge. I will agree all aftermarket ones may not work but in my application the Stant works fine. In fact in the winter the gauge would read a tad below 180 degrees F which the stock one never did. Reason I mention this is if rockauto.com ships to Canada they are about $6 on their site. Also there was breif time couple years ago when Stant was what Mazdatrix was selling for the S5.

 

Mazda USA switched to stant like 10 years ago... the 9U suffix means they used an "aftermarket" supplier.

which creates the odd situation where if you wanted the correct NTC thermostat, you have to buy from the aftermarket.

the stant ones are definitely lower quality, and if the thermostats are anything like the radiator caps, about 1 in 5 would actually function properly new

 

I noticed on rockauto that for the S5 they have two different ones. The "exact OE replacement" that has the jiggle pin and the one I have which does not. I guess the one with the jiggle pin is the one they( Stant) supply to Mazda USA? I may have just got lucky with mine. I think my radiator cap is a Stant too.

So the question is do you buy it from Mazda or figure out which part it is they supply Mazda USA with and buy it at rock auto or somewhere else for much less money? Who made the original one for Mazda and are they selling in the aftermarket somewhere?

Both the S4 and S5 part numbers at Mazdatrix have a 9U in them. In the past all they have done for their part number is rearrange the Mazda part#.

 

No body ever gets lucky with a thermostat. They either work or you get unlucky.

 

the OE thermostats are made by NTC (nippon thermostat co?), and are actually fairly widely available in the aftermarket.

yes, Mazda has the part number as application, section (cooling, suspension, etc) and then specific part, and Mazdatrix moves the application to the back, so its section, specific part, and then application.

Mazdatrix is a little more logical, as all the radiators (15-200) will be right next to each other. Mazda just goes by size, biggest to smallest.

 

The problem: Thermostat

The Diagnose process: 1. Poured coolant all over the place took of the thermostat neck.
2. Boiled thermostat, It didn't open worth at all!
3. Removed belts on water pump and spun it by hand(water pump)while looking into water pump housing to see if the pump was mechanically sound: It was ^draws coolant in*vortex*^.

Put everything back together and burped system
DONE!

Parts Needed: Mazda replacement thermostat with new gasket, New coolant line to turbo from heat cracking. Hose clamps.