For the first 4 years I had my RX-8, I've never had a problem with the cooling system. But I was living in the San Francisco area at the time. I've recently moved to Phoenix and I'm noticing a few problems.

* The radiator light comes on sometime. The coolant level is fine. But, if I'm driving on the highway, the light will come on occasionally.

* The temperature gauge gets hotter and hotter when the car isn't moving fast. While in CA, the gauge stayed in one place once the car was warmed up. But here in AZ, it gets closer and closer to the H mark when stuck in traffic.

* The engine seems to be knocking sometimes. And it has a rough idle.

* The A/C isn't particularly effective when the outside temp goes above 100. It never went over 100 in CA. It's over 100 every day in AZ.

Hopefully, others in Phoenix or Vegas can let me know how the car runs during the summer.

Because of these problems, I haven't been driving the car much since the summer started. I'm lucky enough to have a third car. If I can't solve these problems, I'm going to be forced to sell the car (though I'll have to sell it in the Fall--no one will buy it in the summer with these problems.)

Any help would be appreciated.

 

hey gusmahler:
welcome to the desert!


1. The coolant overflow tank's sensor has been known to go bad. If you're certain that the fluids are topped off, it's most likely a bad sensor. You can replace the tank or disconnect it.

2. When you're not moving, the car can get pretty heat soaked since you're not moving as much air into the system. Our OEM temp gauge dosn't fluctuate much once it hits operating temperature (approx 160-170°F). From that temperature, it will not move again until you're almost at 230°! If you're seeing the needle creeping up, be VERY careful.

3. rough idle is most likely due to the fact that your coils have gone bad. (they are prone to heat failure)

4. Ever had the A/C system checked /serviced?

Don't sell the car, most of your issues can be fixed quite easily.

I'd look into some cooling mods to help your RX-8 out. 1st on the list would be the Mazmart Water Pump. This little guy is capable of flowing MUCH more water and preventing cavitation. That should help with the temps a bit.
How long as it been since you flushed the coolant system? If it's been a while, I'd recommend getting it done and running more distilled water. The car comes with 60% anti freeze and 40% water. Look into a 70 / 30 or 80/20 mix. (water / coolant)

do you have any modifications on the car?

Other upgrades I would consider down the road to help combat that brutal AZ heat:
- AccessPORT. This can reflash your ECU to kick the fans on sooner
- Upgraded Radiator. I have the Black Halo Racing radiator and have seen a nice drop in the coolant temps. (even when I was out in Vegas 2 weeks ago)

I'm sure the rest of the Phoenix crew has some other helpful info on this subject. You'll be in good hands.

 

Vegas cook a lot of Rx-8.

Try to change your coolant to 30/70 (anti-freeze/water). that should help something.

and for the A/C, Rx-8 is known to have a pretty weak A/C, but u can try to insulate the A/C line right above the engine. That helps a lot.

 

You could also add Redline Water Wetter or Royal Purple Ice coolant additive to make it more efficient. I don't think it lowers temps by up to 30 degrees like WW states, but I think it probably does somewhere up to 10 degrees it seems. And WW is cheap at 10 bucks a bottle.

 

raise the rear of the hood to relieve the heat.

 

Just bumping to see if anyone else has thoughts/suggestions.

 

Welcome to Phoenix.

Simple answer - Don't drive the car in the Summer, especially in stop-n-go.

Slightly less simple answer - Don't drive the car in the Summer, especially in stop-n-go with the A/C on and without a whole slew of overheating countermeasures.

Unfortunately, the cooling system of the RX-8 just doesn't cut it here.
There are numerous threads dedicated to cooling system mods here on this forum - many of which were authored by folks like us that live on the Surface of the Sun.
You can remove weatherstripping, modify the fans to come on earlier, better seal the radiator to the engine bay surround and, last but not least, keep the revs down as low as possible when at speed.
Even with a healthy cooling system and A/C, you will still run hot.

NOTE - If your temp gauge gets anywhere near the "H" mark, you are on the very edge of a complete motor failure. The needle begins to move above the middle once the coolant temp gets above 230°, which is already WAY too hot. The "H" is 260°, which is almost exactly where the motor comes apart.

 

So when the AP said I was at 241 on Thursday it probably wasn't a good thing was it? That's the hottest I have ever seen my coolant temps get to. The car said it was 116 outside and I was in stop and go traffic in the tunnel with the A/C on. I watched the temp go from 220 and just not stop. I quickly shut off my A/C, opened all my windows and cranked the heater. I was in a damn microwave at that point but as I slowly moved and kept rpms low through the gears it settled back down to 226/228 and then eventually went back to around 216 or so where it usually sits. Very uneasy feeling as I thought I was going to watch my car melt on me. :-(

 

As you all know this is not an uncommon sight in the Phoenix area.



I have done all kinds of things to try and remedy this. And Mazda has had their engineers out 3 times to record those temps.
So far, as Mazdamanic said, there are a lot of things to do to try and keep the temps cool. But so far nothing keeps it from getting hot under load.
So far two things have kept it kind of under control. MazMarts water pump and thermostat.
Now they do not keep the car from getting this hot but they do allow it to cool down faster when your moving under light load. They will keep the car cooler longer, but it will still get hot when you push it.
Yesterday it was 117 and my coolant temps were in the 210-220 range while doing 75 on the freeway. With the A/C on.
Now when you start getting into city traffic and stop and go it will get hot. 230+

Just be easy on it this time of the year.

I would suggest changing the Factory coolant ratio (60 coolant/40 water)to about 25% coolant and 75% distilled water. Also a bottle of Water Wetter or something equivalent.

You might want to read through this as well. Overheating

 

Just wanted to let everybody know that I used some Royal Purple Ice at the track yesterday. It lowered my coolant temps by about 5 degrees F.

 

i live in texas and i thought i had it bad but dam never seen that much heat

 

Holy **** man! My car never sees above 200F! Damn... I didn't know it could get 120F down south... up here when it get's to about 95F everyone starts to complain... Dayum, I didn;t know it was that bad.
What if you change the radiator (BHR) and get the mazmart water pump? I bet it would help alot.

 

It's depressing reading these responses. I really like my RX-8. And it's paid for. But a car that can't be driven 3 months out of the year is pointless to own. Guess I'll be getting rid of it sometime in the fall. Thanks for the responses.

 

I'm sure there's more people from Phoenix that can chime in. Bump for you.

 

Yea i live in TX and it gets pretty damn hot out here but not 115 deg hot. My car struggles to in the heat but I rarely drive in stop n go traffic (thank god) Think about it for those ppl who live up north where it snows struggle to use their 8 around winter time and almost impossible to drive for those 3 months of winter.....so i guess it balances out.....

 

I got it bad... I live in Idaho, we see temperatures of over 100 degrees (not as bad as Phoenix, but still up there) for 2 months in the summer, and the car stays parked from late October to early March... 4 months. So... half the year, the car is practically unuseable. It's worth it to me, though. Nothing gives the same experience as driving this car.

 

Thanks for the post. I just bought my RX-8 this spring and now summer is in full force out here in Palmdale, CA. I noticed my oil temp is tipping over into the 220s. I lucked out with a short, traffic free drive to work.

 

I just saw Brice offering oil cooler fans for sale.

https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/finally-oil-cooler-fan-kits-178918/

 

there's nothing wrong with driving it, you don't have to sell it.
Easy drives his year-round and does MM.

ANY car being driven around in the desert, where there's no moisture in the air, with 115°F ambient temperatures is going to require a bit more attention and you obviously can't drive it 'like you stole it' during those months.

 

i have alot of the exact same symptoms this is a good thread

 

By the way............. for you new commers.. that's the outside temperture.

 

Bump for anymore info for the OP

Edit: and me, I'm considering moving there soon

 

I was in Hell once, then I woke up and realized I was in Phoenix.

I use to live in Flagstaff, I stopped in Phoenix on my move up there. Woke up at 6:00 am it was already 100 degrees. The new reporter on the morning news was giving it a 10 scale today. Mean if you were outside more then 10 minutes make sure you had sunblock on so you don't burn.

If you want to know what summer in Phoenix is like. Turn your oven to broil wait 10 minutes then stand with your face in front of the door when you open it. That is summer in Phoenix.