I have a 2004 series I with 67k on the current motor I have been using a bluetooth obd dongle connected to my phone to read coolant temperatures among other things. I have found that my temperatures seem a little high as high as 208 F in normal driving and if i let the rpms go up to 8k for a few seconds ive seen temps as high as 221 F and during a bit of playing around i saw 224.5 F which scares me a bit since i know its not particularly difficult to warp a rotor housing. Only things i have done to the car are the throttle body bypass and i am running 5w30 instead of the usual 5w20. ambient temps are between 82 F and 92 F but, seeing as i live in the central valley in California it could get as high as 110 F later in the year. I have checked my coolant and oil levels and do so regularly I also have never let it overheat when i see a spike i slow until the temps drop to regular levels. I'm wondering if there are any simple mods i could do to drive the temps down a bit as i'm worried that in the heat of summer it could overheat in traffic.

 

The fan turn-on setting can be modified with the Cobb Access Port and maybe some others.
Not the cheapest but there are other benefits.

 

Stop driving it you are over heating right now if I'm not wrong the coolant seals can let go at 220 I've got a 04 the only time I've seen 200 is in 85 temp out side and in heavy traffic most of the time on normal running even in the 85 area I see engine temps of only 180 max. No cooling mods on mine yet.

 

These cars will hit 220F stock in the summer. If you want the motor to last, either get a Cobb Access Port (discontinued, hard to find) or some other way to tune the car, or simplest would be a fan controller to turn on the fans at a lower temperature. Mazda made these cars run ridiculously hot to try to meet emissions and it causes everything in the engine bay to bake.

 

Cooling Fan Control Kit by RX-8 Performance | RX8Performance.com

 

Other than to try to sell you some thing I don't know what this guy is talking about. Here is some real data


9. The factory stock thermostat opens at approximately 180°F (82°C). Under normal driving conditions the water temperature should not exceed 185°F. Should the temperature reach 200°F fairly slowly, engine damage is not likely. If the rise is fairly rapid- due to a broken hose or fan belt, for example, engine damage is more likely.

 

And the web page I pulled it from

Rotary Tech Tips: Water Cooling

 

If you are seeing 220F+ in normal driving, there is something wrong. You can cook a coolant seal at 220F.

Given your symptoms, it sounds like your radiator is just old and having a hard time shedding heat (in my opinion). The parts are all 10 years old at this point, so I would seriously consider replacing your radiator, coolant bottle, thermostat, and coolant lines. You can get all the parts from Mazmart for around $550ish + shipping, and I'm sure there are other members out there to help you do the work, it's not that difficult.

As far as mods, one of the reflash tuning methods can help by lowering the fan trigger temp (Cobb AccessPORT $500 or MazdaEdit $370), you can upgrade the radiator to a BHR radiator ($500), you can improve the ducting in front of the radiator, the sealing around the sides/top/bottom of the radiator (make sure air is only going through the radiator), and you can opt for the lower 172F thermostat to give yourself some more head room.

Good job on looking at the raw temp values to see what you are actually running, you just may have saved your engine by being armed with that knowledge.

FYI, the Cobb AP was discontinued for only a few months, it is still sold by the same guy that sold it previously. MazdaEdit is another reflash tuning option that is growing in popularity. Both can adjust the fan trigger temps.

 

I have no affiliation with the company that sells that fan controller. I have used it in the past and it works well and is inexpensive. These cars heat soak in traffic badly. 220F will not break a coolant seal in my experience but is not ideal. I prefer to keep temperatures under 200F onn these cars.

 

I didn't realize that was so hot on these cars. most of my background is in older jeep wranglers some of which happily live at 230 F or higher. I'll try to find the funds to replace my cooling system.

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Excuse me if I chose to listen to not only a mod but some one that's been here sense 07 over you and I realy don't care to test your belief of the coolant seals out. 200+ is not good for any "engine" (not motor) and is especially bad for a rotary

 

No need to be antagonistic niteshade. And plenty of engines can run 220F+ without a problem. It's all in how the engine is designed. Metal gaskets in piston engines can take a lot more heat than the not-so-metal gaskets in the rotary.


IR, 220F isn't garuanteed to cause a coolant seal failure, but it can. The higher you go, the more likely you are to bust one. It's a roll of the dice, and while 220F is low odds and plenty of people have never seen a failure at that temp, it's still possible. Agreed on keeping it under 200F. I prefer to keep it down at the 172F, since that's 48F of headroom, rather than 20F.

 

I always keep all my cars under 200 when the engines were made of cast iron yeah 230 was ok but now every thing is aluminum 220 can warp heads egg shap cylinders just in general give you a bad day.

 

I agree that on any vehicle 220 is hot but, jeep 4.0 and 4.2 l engines are nearly indestructible my jeep ran for two months with only 3 psi of oil pressure and a flat cam with no noticeable drop in power the only obvious issue was a ticking sound from the valve train the engine never quit on me.

My '8 only gets hot in slow moving traffic or when I put my foot down and since I noticed the high temperatures I have been backing off any time it gets over 200 F. Unfortunately I can't just park it as it's my only car but, of the nearly 70 miles a day I drive 60 or more are highway miles where the car sits at 185 F. I figured it was an issue and will definitely do something about it as quickly as possible and in the meantime I will be careful not to let the temps get too high.

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I hope my comment that I come from jeeps didn't sound like I was disagreeing with anyone. I was just trying to say that I didn't realize how close I could be to doing damage because, I am new to rotories. Almost every person on these forums knows more than I do about these engines.

Also thanks for the help and the suggestions.

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No prob my little girls boyfriend had a grand cherachee (or how ever you spell it ) it had 3psi oil pressure a spun main baring gears in the transfer case ground to dust and a long list of other issues but that thing defided all laws of mechanics and still drove down the road.

 

That's the thing with jeeps it's not that they don't break that makes them reliable it's that they keep running even when the engine is completely ruined.

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The following is quoted from myself from this thread. https://www.rx8club.com/series-i-tro...diator-248026/

" Based on some more reading I am pretty convinced that 220F is where you should start paying attention. 230F is where you should be really concerned. Based on the condition of the motor, coolant condition etc etc. 235F and above you are about to invest in a new engine or trade it in after it blows. 240F is terminal."

I had problems with an increase in coolant temps after a radiator install. You can read the thread if you like. After a ton of reading some on this site, some not. I came to that conclusion, not saying that my findings should be etched in stone, none the less I stand by it, because I have personally seen coolant temps as high as 224F and my engine still operates normally. Fan mods are useless unless you are overheating at idle or heavy traffic. If the fans are in good shape, they are more than capable of keeping coolant temps in check, providing of course the rest of your cooling system is in good working order.

You are already one step ahead of most as you do monitor your coolant temps. On extremely hot days you can actually run with the heat on full blast and windows down (yes it's uncomfortable and it sucks, but it beats a tow truck and an engine replacement) and it does it help. I did this before I discovered the foam problem. If it's getting hotter than your comfortable with on the road, you can also do that or just slow down, especially if you just insist on running the A/C. Here in Texas that really sucks, as the open interstate is 75 MPH and I could only run about 65 with the A/C on. I insisted on being comfortable, besides I just repaired the A/C.

 

Mine gets hot when sitting in parking lots in stop and go traffic and when I let the rpms get high and stay there for a few seconds. I have noticed that when the temps get over 206 and the fans kick up that at least in a slow traffic and parking lot scenario they immediately drop to about 200. I'm thinking the fan controller suggested by IRPreformance will help in those scenarios and should help at least keep it from heating up so fast under hard driving situations. I will probably also do a new radiator but, I'm going to see how the fan controller effects it first.

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and I come from old jeeps I'm definitely no stranger to turning on the heater to drive the temps down. Hell my jeep didn't even have A/C.

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Mine does the same. If at idle goes up to about 207F and then drops to about 199F after the fans kick on, so I am going to say it's normal. Unless you hold the car at high idle or other foolish non sense, the car is not going to overheat unless you have a problem some where. Under hard driving, or any other kind of driving for that matter the fans are not used. I am not sure of the exact speed, but once the car is moving the air entering from the front of the vehicle is in essence the fan(s). The only help you will get with fan mod is to keep the car "cooler" at idle or low speed. If that is of value to you, then go for it. Just understand where that mod will be beneficial.

 

I'm actually more worried about it getting hot while I'm in town it gets to about 210 before it drops again. I'm doing a trip to San Diego this weekend so I will likely be stuck in LA traffic on the way there and I'd hate to let the car bake the whole time I have the fan controller ordered and coming by friday hopefully. I also plan on overhauling the system soon but, tires and ignition also need attention soon. I'm not worried about it getting hot under hard driving because it's easy to back off if the temps get high but, when I'm sitting in traffic idling and the temps are shooting up there's not much to do other than turning the heater on.

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it's not the idling temp at 210 that bothers me it's when I'm moving slow in first gear and I see higher than 215 that I start to worry.

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I did a little bit of sealing around the radiator and cleaned the radiator and drive it on the highway in second holding the revs at 8200 and temps reached 213 but, only after going a whole three miles like that I would say that's a notable improvement it was still climbing and would have gotten higher but, it definitely helped as before it would hit 220 in a few seconds.

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Nice just keep a eye on it