ItalynStylion

iTrader: (1)

Backstory Bullet points....

1. Coldest day of the year I turn on the heat for the first time since March.
2. Car barely had time to warm up and the "Low Coolant" light turned on.
3. Topped off coolant and continued to do so for the next week ensuring it wasn't leaking or being consumed.
4. Coolant light comes on every once in a while.
5. Temperature will climb if I'm stopped idling or hitting a bunch of slow stoplights unless I use my switch to manually turn on the fans.
6. With fans on the temp gauge will immediately go back to normal in about 60-120 seconds.

Car has a fludiyne radiator, 3" downpipe (no cat) and a 3"midpipe with a high flow cat. I have verified that there is no coolant being consumed or leaking. Level is 100% full. Weather here in Dallas has been about 60-70 degrees. The previous owner did the linearized temp gauge meaning the temp needle never really goes much over the C. Previous owner also installed a system so you turn a switch ON and the fans engage HIGH. You leave the fans on for 2 minutes while the engine is on and then turn the engine OFF and turn the switch OFF so the fans continue to run for 10 min on LOW to cool the engine off. I've been using this system to manually cool the car down if I see it getting warm. The car does fine on the highway.

But here's the mind ****....it was consistently 100+ degrees all summer and I drove the car 4 days a week and I NEVER saw the temp gauge get even mid way.

Tem120

iTrader: (5)

Alot of confusing things here , first do you have an aftermarket temp gauge the OEM temp gauge is not exactly known for .. well working .

second is you shouldnt drive your car hard unless its up to temp . this is a bad with all cars , but specially rotaries so if you temp gauge never got to opperating temp. thats not a good thing .

the fact that your car is cooling down when you hit the fans manually but not normally , have you checked to see if the fans are turnning on by themselves? withoutthe switch??

also , This low coolant light . when was the last time you flushed your radiator if it was recently it may just be air in the system . if not how do you know your car is not consuming fluids ?

have you checked for white smoke? or any kind of leaks under the car ? drive without AC for a bit and see if when you stop there is a puddle that is not because of condensed water.

I had a fluid leak that I could not find , It ended up being the throttle body coolant return line . which had cracked and had a leak , But being in the middle of the engine it was very hard to spot .

ItalynStylion

iTrader: (1)

OEM. Got the car in February with 32k on the clock. I'm doing the proper mods in order of priority to make sure she's safe. Power FC is in the mail as we speak and I'm planning on using the commander to check immediate coolant temps.


I never do. When the car was warming up still the coolant light turned on.

Good question and this is my thought as well. I'll check here in a bit. I don't think they are though. Could this mean there's something wrong with the thermostat?

No idea when the last flush was since the car has only been mine for about 8 months and still has very low miles. I believe I'm not consuming coolant because there's no white smoke (or any smoke) from the car...ever....not even on start up.

No smoke of any kind as stated above. The AC was run for basically the entire summer which COULD be why I never noticed this. I have NOT been running the AC recently because it's so nice out right now. No puddle under the car at all.

Tem120

iTrader: (5)

I see , well . As for the coolant dissapearing I cant say . you'd need to do a coolant system test you could rent a tester from most autopart stores .

And the fans not comming on may be the issue , the thermostat the car would not cool down because if its stuck closed even if hte fans are blowing and cooling the radiator since its colosed the cold water will never replaced the hot engine water .

it is more then likely a relay , OR when the PO set up the manual switch he disconnected the auto temp , and during the summer when you had AC on , it might of turned on the fans because the fans turn on with the AC so First start with the easy things check to see if the fans turn on on their own or if it turns on with the AC

ItalynStylion

iTrader: (1)

Ahhh, sorry if my original statement wasn't clear. The car is totally full with coolant. I really only had to add coolant once (the first time) and haven't had to ADD coolant since then but I've been checking it every day for the last week or so to make SURE it's still full. So I don't think I'm really losing coolant at all. Sorry if I didn't make that clear.

And I agree, I think the fans may be part of the problem as far as it staying cool when there's no airflow due to the car's movement.

But that still doesn't solve the mysterious "low coolant" light issue. The light hasn't come back in a few days so it's possible I just needed to get the air out of the system like you said.

JM1FD

iTrader: (1)

No. It would be an electrical problem. Either the ECU isn't calling for low speed fans, or there's something in the fan control system that is causing it not to respond correctly to the ECU's call for low speed fans.

As to it not doing this all summer long....did you have the A/C running all summer long? If so, that means your radiator fans were on all the time (to cool the A/C condenser) keeping temperatures stable.

Let the car sit and idle. See if the fans come on as they should, lower the coolant temperature, then shut off. If they do, you have nothing to worry about.

It is perfectly normal for cars of this vintage with electric fans to have fluctuating coolant temperatures. (Newer cars have fancy-*** solid state variable speed fan controllers that run the fans almost constantly but at varying speeds to keep coolant temperatures basically constant.)

JM1FD

iTrader: (1)

My car was throwing a low coolant light every time I started it up for a while. Turns out the hose to the overflow bottle was pinched. It could push coolant into the bottle as the system heated up, but it couldn't suck coolant back in from the bottle as the system cooled.

ItalynStylion

iTrader: (1)

Ok, before going into this....I want to re-state that I have a linearized temp gauge that was done by the previous owner. That being said, I have NO idea what the temp gauge really means or where it should sit. Now with that said, here are my results....

I drove the car for about 15 min and then came home and let it idle. Gauge slowly crept up till it was at the level you see in the picture below. This is higher than I saw it all summer where (in Texas) the AC was run 100% of the time.




Then the fans kicked on automatically (yay!) so at least we know they work. I turned on the AC and the fans went into high mode and cooled the car down to the point you see in the next picture. This took about 60 seconds to get the temp gauge to this point and it was stable from then on. This reading is what I've deemed "normal" for this particular car after owning it for a few months.

ItalynStylion

iTrader: (1)

For individuals who have the linearized temp gauge....where does your needle typically hover?

JM1FD

iTrader: (1)

This is exactly why Mazda de-linearized the gauge. This sort of fluctuation in temperature is normal, but seeing the needle move up and down causes people to freak out needlessly.

The car is fine. The systems are working as designed (or re-designed in the case of the gauge).

/thread

Tem120

iTrader: (5)

/unthread ,

get a correct water temp gauge / Power FC commander

/thread

ItalynStylion

iTrader: (1)

Power FC and commander came in yesterday. Getting them installed/tuned next week.

What is the numerical value that the water temp range should be normally?

JM1FD

iTrader: (1)

Depends on where your fans are set to come on.

There's a thread around here somewhere that lists all sorts of different temperatures and what occurs at those temperatures.

SA3R

Have a search for Dale Clark's "Big Fat FD3S Cooling Thread".

Its probably only a few posts under this thread...... It answers the questions you're asking.

ItalynStylion

iTrader: (1)

Found it! Thanks for the suggestion. Here's a link for anyone else who comes along later with the same question.
https://www.rx7club.com/3rd-generati...thread-571088/

Tem120

iTrader: (5)

it really depends on a couple things I believe the thermostat OEM completely opens up at 86C , and the car is concidered warm at 80C anything over 110 is SHUT ME OFF i'm HOT

My car normally hovers between 85-90 and when ti gets abused it does go higher. was up tio 106 , then I started cruising and letting it cool off .

My fans I have set to turn on at 86C .

ItalynStylion

iTrader: (1)

I did a few tests during the day and confirmed that the temps stay what I'm considering "normal" when I put the AC on to run the fans. I'm going to quit shitting myself now haha. Power FC will be installed Friday so I can get a numerical idea of where she's sitting.

Thanks for all the help guys.

ItalynStylion

iTrader: (1)

Got the power FC installed and tuned on Friday. Car is better than it ever has been. I'm in love!

I had Chris pressure test the cooling system too. He said it's fine and topped off the coolant and got any residual air out of the system.

However, my coolant light is STILL coming on inermittently!
Sometimes it's on for about 15 seconds and then turns off. Last night it was on for about 4 miles. Of course, now that I have the PFC, I'm more comfortable telling the coolant light where to shove it since I have a digital readout of exactly what the water temp is. But the damn light/alarm is loud as ****. Any other ideas? Is it possible the sensor is failing?

Tem120

iTrader: (5)

sensor may be going bad , or the wire going to the sensor may be bad . check it out see what condition the wire is in . its pretty easy to get to .

Dvst8

iTrader: (6)

Sensor is most likely failing.

ItalynStylion

iTrader: (1)

Chris at Rotary Performance said a similar thing and checked the wires. Said they look fine. So I'm thinking that leaves us with the sensor failing. Anyone know if it's a bitch to replace?

ItalynStylion

iTrader: (1)

Part number is N3A1-15-610A. Figured I'd post in case someone else needed to know later.