Scribobin

My radiator indicator light kept going on. I was beginning to think it was a faulty sensor, but instead I figured out the fix myself.

The light came on because the radiator overflow reservoir was just a little too full. Simply remove some of the liquid from the reservoir and the light will go off after you drive the car a few miles. Light has never come back on.

yiksing

Lol this is new...

mrmiata7

Mine comes on too. Driver's door remote unlock failed too. Am getting it serviced Monday morning.

2006 Blue Green Metallic with 19 Inch Ruff Racing Chrome Wheels.....

RodrigoSoares

since there is a tread for this issue:

my radiator light keeps coming on all the time. going to try to explain the best i can:

i made several mods to the car and one of those mods was the radiator. i replaced the stock one with a mishimoto racing radiator. before the mods, i had the radiator light 2 or 3 times, always when i was pedal to the metal, around 8000, 9000rpm for a while. at first i thought it was the extreme pressure of the water circulation or lack of coolant ( i can get temperatures of 40 celsius where i live). put some more coolant and can´t remember if the light came on again before the mods. i remember drive it for 5 or 6 minutes once, between 200 and 235 km/h, 6th gear and no radiator light.

now: after the mods i had a couple of problems: first, it didn't run idle (bigger injectors, turbo, bla bla. solved with a first base map from MM); second, gas leek (solved, injector o-ring not doing its job). the first times i ran the 8 after the mods and after solving this issues, i only got to 3000, 3500rpm. no radiator light. but when i go up to 4000, 4500rpm for a while (30s sometimes less) the radiator light comes on.

the coolant reservoir is full. green, 10% for temperatures -5C.

i always let it heat to running temperature when i start it (around 84C)

when i run it at 3000, 3500rpm the temperature on the AP is 86 to 88C

when i run it above 4000, 4500rpm the coolant temperature on the AP is 90 to 92/93C

when the light comes on, i take the foot of the gas, the rpm drops and the temperature drops, light goes off. if i run it around 3000rpm steady, no light, temperature steady at 88C

park it, open the hood, extreme heat coming off (the kind you can see the heat waves)

any ideas? suggestions?

thanks,

Rodrigo

Mazurfer

Rodrigo,

It's a known issue. But since you are across the pond and not on the site much..............I'll be easy on you.
A simple search would've brought up at least the following two threads!

https://www.rx8club.com/series-i-trouble-shooting-95/coolant-bottle-greatest-secrets-revealed-182793/


https://www.rx8club.com/series-i-trouble-shooting-95/coolant-light-dash-118947/

The first one is my thread and rather detailed, but the answer(or your options) are in the second post!

The rest of you guys............yiksing was being sarcastic! jeez!

bse50

Searching is an art that is being slowly forgotten!

RodrigoSoares

thanks for the info and help. I didn't realize that it was such a common issue and so debated. one more question: can you tell me the normal or average temperature of the engine with everything running fine? for example, i'm going full throttle at 9000rpm, what should be the normal coolant or engine temperature? because i didn't find any temperature information. i think the normal running temperature is 84 - 86C (celsius) but when i pushed it a little, the temperature goes to 92/93C and because of the damn light i didn't went further... and got scared.

thanks

bse50

93°C is a good running temperature if you're pushing the engine. I would usually back up when seeing temps above 100°C just to be safe but 'till 104 you should be fine provided that you step off the gas!

RodrigoSoares

so regarding the damn radiator light pops on, up to 100ºC is fine, more is dangerous... yes?

bse50

The radiator light may very well mean nothing, those sensors don't last long
I would back up before reaching the 100°C mark on a daily driver if possible. I consider 95°C to be the highest safe average temperature. 85\90 would be ideal =)

RodrigoSoares

that's my average temp when running around 3000, 3500rpm with 40ºC outside.

thanks again. tomorrow i'll make another run, to the end of the day, more cold outside and see to what temps the engine goes.

Mazurfer

Yeah, I would agree. I have an early kick on mod for my fans, but even beating on the car(or in miserable stop and go), I've yet to see more than 95°C worse case......with outside air about 35°C. If I did, I'd start checking things.

This would exclude track duty however.
I would probably push my tolerance range a little higher if doing significant track time.

RodrigoSoares

what would be a great fan upgrade? should i vent my hood?

RodrigoSoares

just got back from another run. this time during the night. cold air ( between 20 to 25ºC ). let it heat to 84ºC, idle and then went for the ride. made about 40km, most of them in 4th gear, at 4500rpm, steady. pushed it to 5500, 6000rpm and the temperature only showed 88ºC, dropping instantly to 86ºC when drop the rpm to 4000rpm. no radiator light.

my conclusions: the outside temperature in my area is a problem. with 40ºC outside, running at 4000, 4500rpm the coolant temperature goes to 91, 92ºC and radiator light comes on, sometimes at 88, 89ºC.

question: does the radiator light comes on because of all the issues discussed in the referred topics by mazsurfer? shouldn't the cooling system of the 8 be more efficient? my cooling tank is full, bigger radiator and fans working fine... more tests to be made :p

yiksing

@RodrigoSoares: i'm getting the same thing, light comes on if im at 4k to 6k for 10 minutes+, goes off if I go down the revs. During spirited driving the light will be on until I drop revs to real low rpm.

I have a vented hood, though I do not have temperature taken it seems to work very well

shadycrew31

iTrader: (6)

Radiator light can come on when it is low coolant or overfilled coolant.

RodrigoSoares

how long do you have this issue? today i made another run, AC, headlamps, rear defroster, 4th gear, 4500rpm, after 1 minute, light came on. outside temp around 25ºC. coolant temp only went to 90ºC. dropped revs to 3500rpm, light off...

RodrigoSoares

hum... mine is overfilled... thought it was low and put some more :p

shadycrew31

iTrader: (6)

LOL dont worry mine comes on as well. I have a rerouted overflow hose so Im just going to run it until it spits it all out.

didyette

Hello everyone:

I've been reading as many posts as I could find regarding the engine coolant sensor light and the radiator. Here is my question: I have an '04 RX-8. I started having the issue with the coolant light going on and off about 3 months ago. During that time I took it to three mechanics, including a Mazda dealer to have it checked out. All of them said the coolant level was fine. One said it could need a new radiator cap, so he replaced that and added more coolant to the reservoir tank. However, this didn't stop the problem. I came on here and read all about this being a common problem and usually means a bad sensor so I stopped worrying about it too much. However, this weekend I decided to get the tank/sensor replaced and took it in to the dealer. They checked it out and said that I have a small crack in the radiator. There was nothing leaking because it was so small the liquid would evaporate and just started crusting on the radiator. He also said my sensor is bad. I asked why they didn't detect the crack last time I brought it in and he said that the last technician was probably not as thorough as this one. Soooooo, do I get a second opinion about this? Or should I believe what he tells me and get my radiator replaced? Thank you so much for your advice on this issue.

invasion08

iTrader: (7)

The sensor is know to fail. I would get a pressure test on your coolant system first. Then you would know for sure if you had a small leak. If you haven't been losing coolant then you just need a new coolant tank.

DocBeech

iTrader: (1)

Im a couple weeks away from having a vented hood. I will let you know how it goes. I will probably only run the engine cover when it rains though lol. So we will see if it improves cooling or not.