My 8 overheated, what do I do
 

After 20 overheating post in the past week, I thought I would share a compilation of all the suggestions I think I made. Thanks to Kelly for the initial question, and the follow up that led to the discussion. Pretend you are Kelly

So Kelly, your RX8 overheated..

A few questions. How did you know it overheated? Was it just spitting water? Was there a huge cloud of steam? Did the gauge just move? That will give us a place to start thinking about how to help. For me, the first time mine got hot is scared me.

You saw smoke or steam coming from under the hood, See Option 1.

If there was no smoke or steam from under the hood, and the gauge just moved to the right, See Option 1.

Option 1: If the pressure cap releases you will see the steam, you may see the needle go up at the same time. A lot of folks will tell you that the world ends if the temp gauge moves. You did the right thing shutting down as soon as you saw something wrong. Mine almost pegged the gauge. I did not notice until the AC cut off because it was so hot. My bad. You likely did better than I did. I put another 60,000 miles on my car since then, with a lot of track time. There are a few things to check. I am assuming some familiarity with the mechanics of the car, about the same level as my kids and/or wife. If these steps bother you, get some help.

I highly recommend getting something that will tell you the car is running hot. Some like the ODBII connector with a smart phone and app. Personally, I want something always on and in the car. 3 of our 4 cars have an ultragauge. They are about $60. You buy them directly from their website. I think they give you a rebate if you prove you followed the installation instructions. If you can borrow something that will read the ODBII data, that is great. It should be able to tell you temp. If you post your location, there may be a local member that can help.

Let the car cool down!!! Then add water, then get it someplace safe. Then LET IT COOL DOWN AGAIN!

Now, top it off with water to the fill line and do not tighten the cap, just put it on to the first click. The will leave the cooling system unpressurized. You just want to keep it from burping out coolant. First, see if it starts. If you get a lot of steam out of the exhaust, or it will not start, things could be bad. If it starts, go to the next step. If not, or you get steam from exhaust, or it will not turn over, you likely need professional help. Post here for a good mechanic in your area. We all have people we will recommend you use, and likely some to stay away from.

Second, you can test the fans. After the car starts, let it run a minute, then turn on the AC. Both of the fans on the radiator should come on. You should be able to hear them. They only run when the compressor runs, but it will run for a few minutes when you first start the car. I recommend having the hood up. If they do not come on, you have likely found a culprit. First check the fuses for the fans, then check the relays. There are a few threads here about troubleshooting the fans. If only one fan comes on, then it is either a bad fan, or bad wiring to that fan. Likely it is the fan, I am not sure I have seen a post with bad wiring. But, check voltage going to the fan if you can, without the engine running. The relays treat both fans the same. You can turn on the key, jumper the relay, and test with the engine off. If the fans work, go to the next step. If that sounds too complex, post here from some local help. An offer of beer helps.

Third, it is time to check the thermostat. This is best done with something that can tell you engine temp. Without that, you risk overheating again as well as getting a burn from hot coolant. If you do not have the device, you can continue, just be VERY careful. There is hot water and a risk of burns. Turn off the AC. Very carefully remove the radiator cap (remember, it is not all the way attached, so there is no pressure in the system). Make sure there is water still in the tank. Add some if it has gone down. You should be able to see the surface. Watch it closely. After several minutes, you should see it start to move around. It may go up and down, it may swirl. This is the thermostat opening. If this happens, you have a thermostat that works, a water pump that that works, and if the fans came on you have all the necessary pieces of a cooling system. If the fans come on, and you are not seeing any swirl, and the AC is still off, you have a bad thermostat or water pump. The engine is getting hot, and no coolant is going through the radiator.

This is where it is really nice to have the gauge that reads temp. If you have one, tighten the radiator cap all the way. Then watch the temp. You should see it rise to about 185, sit there for a few minutes, then start to rise again. The pause is when the thermostat opens, it starts to rise again after all the cold water in the radiator has entered the engine. It will rise until the fans come on around 207-210 degrees or so. Then the fans should kick on, and the temp will go down a bit. Again, if the temps keeps going past 210, and the fans come on, and it does not go down, shut it down before 215. You have a thermostat or water pump problem.

If all of the pieces test out, the overheat was caused by something else. Could have been a plastic bag that got sucked in the intake, a hot day, low coolant. It is a good idea to keep an eye on coolant for the next week or so. Also, check out the cooling related mods in the Congrats thread below. Specifically the fans on low mod and the foam around the radiator mod. Both helped me a great deal. I wrote those posts after mine overheated. Making sure the fans work and making sure the air flows the right way are 2 big things.

Remember, Coolant is HOT. Also, something like an ultra gauge is a great thing. You can set an alarm to come on when things get warm, as opposed to the needle moving when things get freaking hot. Fans on low kept my temps around 185 degrees, even in the summer. This is when the thermostat opens.

Good Luck.

Room to fix whatever I screwed up above.

More room to fix stuff if I need it.

Hello 04Green. Long time :) My passenger side fan stopped working :( Relays checked out ok. Way back last year the damn rubber grommet got stuck and jammed the same fan. It worked until last week though. Could it be because of that? It's like, sometimes it works and sometimes it doesn't. I can tell from the temp spikes from my OBD2 scanner. When it's not working, the temp would climb up pretty fast. And then maybe 5 hours later when I take the car out, the temps stay fine, and the fan works. But for the past couple of days it stopped working.

What could be the issue?

If the motor is dead, is there a way to replace the motor only without pulling the assembly out?

I don't want to break the radiator nipple off.

Ok so just a quick few questions. Are you able to get to the fans to.spin them by hand without removing stuff? What do I have to take off? And also if the fan fuse is blown there is no way to test the fans without it right?

@ Aston, sorry, missed the post. Hope all is well.

@ Palley, you have to have tiny hands, or know someone who does, to get to them. If I stuck my hand down there, it would be after disconnecting the battery.

04Green

I have a RX8 2004 M/T since last year and i think i having problems with the coolant system. I used a Scan OBDII and when i rev the car at 7000rpm after 4 - 5 minutes the temp claims up to 220 and keep claiming. yesterday I install the control kit fan and the fans are starting a low temp (185F) now but the car is still reaching high temp, i don't see any leaks, the level of the coolant is at max. I'm wondering if maybe you could help me. I live in Orlando, FL.

Thanks!

First off the engine wasn't design to rev that high while parked. I would drive the car around and monitor temperature in real time (traffic, street driving, mix of AC on and off). Mazda coolant or any compatible 50/50% w/w coolant doesn't boil until 226 °F (108 °C) at atmospheric pressure and 248F (120 °C) at ~8 psi - system pressure. Remember folks the system is under slight pressure for a reason - higher boiling points.

Questions for you:
- how fresh is the coolant and when was the last time the system was flushed
- what quality coolant at what concentration (and did you use distilled water to dilute)
- how clean/straight are your radiator fins ?
- coolant leaks that would decrease your system pressure and hence BP of coolant
- coolant level OK at operating temperature
- oil quality and at level?
- oil cooler in top shape (fins straight for max air flow)

Curious minds want to know.

I was driving the car,the car was not parking when this happened. Yesterday in traffic the car hit 228F with the A/C on it was 103F temp outside. I changed the coolant about 8 months ago, it is 100% coolant, the radiator was changed about 1 year ago and the cap. the coolant level is ok at operating temp. i changed the oil about 1500 miles ago, about 250 miles add oil to the max level. yesterday at night i install the control kit fan and now the fans are starting at low temp 185. after that I drove the car and there is went it hit the 220F it was in a highway and i just down the rpm to 3000 and the temp down to around 205F (this is after i install the control kit fan), before that, the car was reaching 228F in highway around 7000rpm.

Normal coolant temperatures per the Mazda Repair manual for the Series II (S2) are: 70—110 °C.

Rare but the engine coolant temp (ECT) probe may be failing. Normal resistance for the ECT is shown below and is part of coolant testing at the shop:

ECT sensor resistance
Water temperature (°C {°F}) Resistance (ohm)
20 {68} 2,205—2,695
80 {176} 287—349
91 {196} 227—240

Is it normal then? Mine is a S1 2004 and if I don't let go the gas I will just keep getting hot

Hi,

I just finished reading your post but i did not seem to answer the probleem i experienced today.

Drove on the highway and saw my temprature going op to 3/4 between L and H. Directly stopped my car where i could and it was just hitting H. Checked under the hood en there was a little bit of smoke comming from my coolant tank. Checked the coolant tank and there was nothing in it so i immediately filled it up with water, but it was after one minute or so gone. So i checked under my car and saw from the passangerside drops of coolant/water fluid dripping on the road. Directly after that i checked my oil, was on a high level and looked like it always does. Information of the car:
2004, 114000 KMS, rebuild by a specialist about 3000 KMS ago.
Fans work as they should, car did not make weird noises en i just turned it off without any other weird things going on.
My question:
How much damage is there probarly done?
What can be its cause?
(Sorry for bad english).

I thank you a lot.

Okay so my coolant reservoir busted while i was driving yesterday, it started overheating so i shut it off for a few minutes then tried turning it over and it barley turned on. I limped home overheating and then it died when i got home.

You most likely killed your engine.

Hate to break it to you man, but if the engine died on its own, it most probably busted a coolant seal.

New owner question
 

Hey guys, i realised my rx8 is lower in the front then in the back... it scrapes sometimes. How can i know if i have ajustable suspension or if it comes stock like that. The back end is higher then the front. How can i know if i can ajust my suspension?

What does ride height have to do with overheating?

I would try putting you face in the direction of your suspension and opening your eyes.

Hi, I'm new to this forum and to owning my RX-8.
I have a 2007 Mazda RX-8 Manual. 126k miles.
I just moved to Arizona and Its really hot here.
When im driving and I have my A/C on the Temp Gauge need starts to go up so I turn off my A/C. Just got a fresh flush to the radiator. Any ideas? Ive searched the forum and there no exact answer to my problem. And if there's anyone in AZ that can help or knows a mechanic that is fair let me know. Thanks

Unfortunately, the cooling system is not the best in these cars--especially in hot and dry climates. Here are some options:

1. Fans. Check the fans for proper operation. There are rubber grommets in the airbox that can fall into one of the fans, when the air filter is changed. One can sometimes stop the fan and burn out its motor. The fans also weaken over time and slow down. You may need to replace them. the Flex-A-Lite 420 and 490 fan shrouds are popular, high performance replacement options that fit with only minor modifications needed.

2. Radiator. The stock radiator is barely adequate. CSF and Koyo make reasonably affordable, all-aluminum radiators that perform better than stock. If you replace the radiator, plan on replacing the coolant overflow bottle at the same time. They usually break during the radiator replacement process.

Does the temp go back down when you turn off the AC? Are you spilling coolant? Do you overheat when traveling at speed or just crawling in traffic? If you're only overheating in traffic, it's the fans. Like Steve said, check for rubber grommets on the radiator. The stock air intake has 2 small rubber grommets that hold the air intake in place. Sometimes when fixing the intake back on, they fall straight down towards the radiator and get lodged between the radiator and the fan blades. Remove the battery, battery tray, and the air intake and check the radiator for rubber grommets. Check if both fans work while you're at it. If they both work, and you're only overheating at idle/traffic, the fans aren't spinning fast enough. These fans slow down with age. Sure they're loud. But they might not be spinning fast enough.

ok so I checked and when I have my a/c it over heats after 20mins and I looked at the fans I can hear the one below my air filter but with my a/c on the one below the battery I can see that it is not spinning. How do I test if the fan or motor is bad or if power isn't getting to it? When I turn the a/c on I hear the click of the relay but that one fan doesn't spin hmm

The click is probably the AC compressor. Not the fans. Check the fan relay's inside the fuse box. If they're working fine, take apart the battery box, unplug the fan motor connector and check if it gets power with a tester. If it does, you need a new fan motor.

how do I check the relays? What kind of testing? Is there a way to put power to the fan and see if it moves? Or what is the tester called?