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?

Only tester you need is a stout piece of wire.

There are three relays marked 'fan' in the front fuse box, #1 is for the smaller fan (if I remember right) #3 is for the larger. Ignore #2, it just does some fancy bridging to run both on 'slow'.

Pull the relay and you'll see four sockets, two small and two larger. With the ignition on, but engine not running, bridge the larger two with your wire - that fan should run. No run, you'll need to check if the motor is jammed (that's common) or you need a new motor.

When you push the airbox down into it's rubber grommets, they can be popped through, right down into the fan blades below, jamming and burning out the motor. Been there, T-shirt acquired.

hey thanks ok so not sure if I'm testing the relays right but I do know that it's the fan under the battery do you know which fan relay that is?

The one that rotates the fan under the battery when bypassed....that one.

for US S1 RX8s Fan #1 is on the RH/passenger side and Fan #2 is on the LH/driver side


https://cimg1.ibsrv.net/gimg/www.rx8...7a04b4bfb9.jpg

Original S1 Fan Control - May have been modified later by Mazda



https://cimg1.ibsrv.net/gimg/www.rx8...5214da3bee.jpg
Original S1 Fan Wiring






.

My point was that if he bypassed relays #1 & #3 he would KNOW which fan works or doesn't - problem solved, no?

My point was to help him with the actual diagrams that allow him to figure that out, yes?

passenger fans go out ask rotary performance i dont work there

Hello my rx8 cooling fans are not turning on both of them are not turning on. I have tested them out of the car and they both work but they do not turn on when put back in the car I thought it was the coolant temp sensor and I tested it via paper clip and it still did not work I do not know what is wrong please help

There aren't too many options: fuse, fan relay, motors, sensor. You proved the motors work, so check all the fuses and relay next. My bet is the relay.

When my car is running for awhile it starts to smoke from the coolant reservoir area and idk what the problem is i was thinking it could be the water pump or thermostat went bad!

Could be the fans, could be the thermostat, but the damage is done, your side O-rings are melted.
Rebuild time before you do any more damage. After the engine shuts off, the coolant will enter
the chambers, and mix with the oil....run it much longer and you will miss the rebuild window and
need a new short block.

how can you be sure that’s the problem??

How high does the temperature needle go?

Is it possible to set the temperature when the fans will come on?

yes you can do it with a tuner (cobb, mazda edit, adptronic) or i believe they make a much cheaper option. you need to figure why its overheating tho and not drive it till you do

Not adjustable, but set to a more suitable temperature

https://www.rx8performance.com/produ...an-control-kit

so i have an 07 and i was driving down the road at about 45 when i saw the temp gauge start slowly climbing over the mid point( ac on) i pulled right over and cut the engine. i checked under the hood and there was no steam, fans were spinning, no leaks, and coolant could be seen in the bottle. i closed the hood and when i got back in the car and turned the key it was back at the mid point on temp.i started the car right up and it stayed in the middle so i drove home with no issues. about a week later the same thing happened again this time at highway speeds. it seams like a sensor issue but i wanted to feel out some more experienced people. its at 128,000 miles no rebuilds yet and im almost certain water pump is stock. i have only had the car for about 6 months.

Drifting & Temp went to H, then dropped to normal after 15 seconds.
 

I tried making my own thread but it said I couldn’t. I was drifting yesterday & when I stopped I noticed my temp gauge was all the way at H. I don’t know how long it was like that for but as I was slowing down and coasting it went back to normal temp. Coolant was everywhere.

Today in the morning I refilled coolant with a 70/30 mix. No smoke out the tail pipe, starts fine cold, starts fine hot. Everything seems normal except for one thing. It makes a sound around 3.5k rpm till 4k rpm. I have a video link here: https://www.reddit.com/r/RX8/comment...tm_name=iossmf

I been driving it and it doesn’t overheat I think it just got too hot for what I was doing. It’s the only time it’s done it and I was pushing the car the hardest I ever have. My concern is engine damage as I only have 10k on this motor. Please let me know what you think & or what I should do.

thanks!

Maybe you got lucky, maybe not. Pull the plugs and see if there's coolant on them.

And invest in a better rad, etc. If you don't have the engine under tray, put it back on, it's a key part of the radiator airflow design.

If you know anything about our 8s you know that excessive heat is the bane of their existence. Monitor temps religiously. To that end the OEM coolant gauge is unhelpful, i.e. it is not linear by design. As temps rise it will continue to read "normal" within a "significant elevated temp range" ...until it reaches an avalanche temp; THEN it will it rise to actually display "HOT", which m/b too late. Point being ...I strongly suggest to install an aftermarket gauge w/ a programable warning temp feature if you intend spirited driving AND want to properly monitor coolant temp. This relieves the immediacy of attempting to monitor ...while you're attempting to enjoy your 8.

The above merely addresses the monitoring aspect. Max ambient temp in the Bay area is only ~ 60°F this time of year. So, if your 8 is overheating at this temp ...it m/b worth looking into increasing the robustness of your cooling system, e.g. system flush, upgraded rad., reduced fan initiation threshold, secure under-tray (as was suggested), sealing around rad, etc. as well.

All the best.

So this may be less of an overheating issue at this point and more of an engine issue, so move if need be.

First some back story, I hit a deer a long time ago, the only damage (that I or the shop noticed) was cracks in the paint on the bumper, and a fog light. About 2 years ago I bought my house, when parked (about a year before) the car ran but had loss of power. I figured I would be able to drive it to my new house, about 15 miles away, I had severe power loss and basically finished my trip at like 20mph and nothing above 3000 rpms. The car overheated and died as I was pulling in and has been sitting pretty much since then.

I've started the car since then usually just trying to get it to redline (no luck with that), let it sit and idle once and when I came back to it it had died (either overheated or choked itself out). Pulled off the cat last week and sure enough the inside was breaking down, without the cat it would start and redline and had all of its power back. I went to go into town and get some bolts to put the exhaust back on, on the way there the temp gauge shot all the way up, I turned on the heater and the temp gauge started going back down and then dropped completely, then the car overheated and died again.

I called a tow truck, and while waiting noticed there was oil coming out of the exhaust, keep in mind there is no cat on the car at this point. The oil was diluted a little, but no foaminess or discoloration.

Anyways, I get the car home and start taking it apart and theres a big hole in the top of the radiator right beside where the bottle connects to it, I assume the damage there was done when I hit the deer, and just got worse over the years. I don't know how many miles I put on the car from the time of hitting the deer till when I parked it but never had any issues with overheating until I moved. So from then till now I would say maybe 30 miles, plus the time it was just idling and died.

So my question is, do I need to pull the motor and replace gaskets, since there was some oil coming out the exhaust? Or is there possibly another explanation?

Gaskets are probably the least of your problems, that engine sounds toast. They do not survive overheating very well and there's not really any point in spending time and money on a seals to find out whether the big parts are still good. It's not like a piston engine. Get a new / rebuilt engine instead.

Sounds like a lot of coolant boiled off through the hole in the radiator. There should be coolant stains all over the place?

​​​

So either way, I'll need to pull the motor at least?

There really isn't any staining from the coolant maybe a little on the radiator right beside the hole but not anywhere else that I can see.