I've read quite a few threads on the forum and still can't duplicate my exact problem. I plugged my Accessport in and have been monitoring my coolant temp for the last few days. The local temp around the denver area has been in the 80's. My coolant temp on city streets ranges from 203-244 degrees. It cools down slowly on the hiway but still does not stay a consistent temp. It varies from around 203 to 217. The coolant level is good and it looks very clean. These figures are from the Accessport. I assume it is accurate. The temp guage stays roughly just to the left of center until the temp reaches the 230-240 range and then is about 3/4 to the right of center. I put some wetterwater in it yesterday with no noticeable results. I can turn the heater on full blast and only notice about 2-3 degree cooling difference. So the extra circulation doesn't help. Anyone got any ideas. I'm leaning toward thermostat but haven't cancelled out water pump. I've even looked at aluminum radiators but had rather go cheap first and start with the thermostat. The wide fluctuatons in temp is weird. The fans seem to be working also. I noticed on a thread somewhere that you could adjust the fans run time or on-off time..not sure. Anyone out there got any better ideas.
Thanks for all replys
Jim in Denver

 

maybe a partially stuck thermostat?

 

Any water in the tail pipe?

Do you need to add coolant regularly?

 

No water in the tailpipe. I thought of the partially stuck thermostat. I talked to my local mech that works on jap cars. He don't like working on wankels but will do any other maintenance on jap cars. I'll have him do the thermostat next week. I'll just park it til then and drive the trusty miata.

Question: are RX8 water pumps going bad known for this

Oh, and no I don't have to add coolant. I actually had to let a little boil out in order to add the wetterwater.

 

Honestly, the first thing I would do would be to clean the radiator and condenser fins as best as you can get them, to make sure enough air is flowing through the radiator at highway speeds.

If its clogged up, its not going to cool off.

The next thing you can do is make sure the engine isn't misfiring, or creating extra heat that your cooling system needs to get rid of. Some threads have said that the cooling system on the early cars is barely adequate to do the job on hand.

But other than that, new thermostat, new coolant, new water pump is about all you can do easily. Might as well do them all at once.

The only other thing you can really do is test drive another car similar to yours, and see if it has the same behavior. Heck, I'd be willing to have you plug into my 2011 just for comparison's sake. I'm just up the road in Arvada, or in boulder when at work during the week.

BC.

 

Hi Bladecutter,
Well, I've put Denver as my location on the website but I actually live in Arvada also. (nobody ever heard of Arvada) I'm roughly at 62nd/Wads. I've actually thought about the Cleaning, Thermostat and water pump. I've even priced the Mitsumoto aluminum radiator for $250.00. At that price it's almost worth it if your gonna open the car up anyways. My friend at Japanese auto over off Ward Rd. does most of the work I don't want to do. He's honest and I can depend on him for quality work. He don't work on Wankels though..bummer! He'll do all the work we spoke of though. Don't know how much a water pump is, but I'll soon find out. I'd really be interested in seeing the 2011 RX8 though.
I'm at 303-nine eight one-4631
See Ya,
Jim

 

Get a BHR radiator....stock radiators are way too small

 

Okay. First things first: STOP DRIVING IT! Those temperatures will ruin your engine.

The most likely culprit is your fan system. Both may not be working. There have been instances of a rubber grommet falling down and jamming a fan, frying it's motor. You (Or whoever is going to be working on the car) should remove everything that blocks your vision of the fans or put it on a lift to establish if both fans are functioning.

Make sure your car is equipped with an engine undercover (These have torn off of some cars) without which you will be directing air under the car that should go to your radiator.

If these other things are not the problem you would then test the system for leaks, internal or external by doing a pressure test. I don't normally apply more than about 16 psi on most systems.

Installing a better radiator or water pump or thermostat will not cure what is happening unless one of these items is presently bad.

Hope this helps

Paul.

 

Jim,

If Mazmart says check the fans, check the fans.

This weekend is already tied up with doing things, but maybe sometime next week.

BC.

 

check the foam around the radiator while you are at it. Make sure it is sealed well.
OD

 

Thanks Mazmart,
I know one of the fans is running for sure. I can hear it. Funny thing is, I can be reading high temps and shut the engine down and sometimes the fan is not running and sometimes it is. Sometimes it runs for 2-3 minutes and sometimes only a few seconds. I've been suspecting this all along but I'm just new to the 8's. I drove it yesterday due to it being a cooler day and it only ran up to 203 degrees once. I shut down the engine in the garage and no fans running. I'll take it to my mech Monday and fill him in on your suggestions Mazmart. Thanks again for the info. In the meantime I'll look for plastic bags in front of the radiator or whatever else may be in there. Never know in the Denver area.

P.S. BC; I'm good with that..I'm working a Mgt slot next week. I'll be doing an 0630-1530 shift all week. LMK if you want to hook up. Thanks

 

Aside from possible thermostat or WP issue........
Get in there and take a look............Car off............spin both fans by hand and see if they spin freely.
Then.......................start the car and let it idle..........eventually you should see and hear one fan come on(which you already know), then verify that the second one comes on after awhile.........not by sound but visually. And of course keep your hands out!

This statement is NOT that unusual. "I can be reading high temps and shut the engine down and sometimes the fan is not running and sometimes it is. Sometimes it runs for 2-3 minutes and sometimes only a few seconds."

 

I know at least one fan comes on at 203-205 degrees, runs for a little while and shuts down. I really can't tell if both are running or not. It just don't seem to run long enough or come on early enough to me. I'll have to figure out a way to look at them. I don't have a lift.
The belly pan is in tact.
There are no leaks anywhere
It actually sounds like only one fan is turning. Hard to tell. What is the easiest way to access them for a look or spinning them other than putting it on a lift. Any one got any ideas?
The radiator and condensor looks very clean from the front end view
Is it true there is a way to adjust the fan timing???????

BC..You know of a decent 8 mechanic in the Denver area?

 

Jim,

I don't know any decent mechanics in town, as I have a new one (no need yet), and I always do my own work on my vehicles unless its something I just can't do (alignment, drilling broken bolts out of the transmission case on my old Boxster, etc).

I have helped Slvrmzdrx8 with a couple tasks on his car so far.

I'm sure there's a good thread on the radiator issue to help troubleshoot it easily.
You find it, and we can get your car up on ramps at my place, and give it a look.

BC.

 

I had a tacoma and I tested the thermostat by just placing it in a boiling pot of water on my stove and noticed the thermostat opening up, I'm not sure if there's any difference in testing this thermostat. Another thing is that I think there's a bleeder valve on the thermostat, might want to make sure that's in the right position on my tacoma it was 12'o clock if I remember correctly (not sure if the rx8 has one)

 

Well I agree some with Paul especilally about not driving it when the temps get at of near 240......You must check the fans and make sure both are working, the engine undercover does direct air toward the radiator but not having one in a cool place like Denver should not be an issue. The stock radiator is too small for any spot that has any heat issue. Mazmart and BHR both sell a larger radiator that should solve most heat issues. Mazmart also sells an upgraded water pump and thermostat that will help keep it cool when you finally get it there.

 

He still needs to verify BOTH fans are working/not working first!
Then it's off to the thermostat, water pump, radiator................in that order, IMHO.

 

Well, Here's the latest. I took the 8 to Mazda of Lakewood Monday. Their RX8 mechanic (the only guy there who wrenches on them) said he changed the thermostat, drove it through town all the way up into the hills and it ran perfectly. Both fans were working to spec. No ECU codes. He also stated he has been in contact with Mazda before on these RX8 heating issues. Mazda told him not bo be concerned until the coolant temp climbed above the 220's. I know I've heard conflicting stories here and I appreciate them. I told him I was concerned about frying the engine. He said Mazda would replace the engine as long as I didn't allow the engine temps to exceed these figures. He has replaced them before but not due to overheating directly. Overheating may have been a contributing factor but not the primary factor in any engine replacement. He pretty much said my "overheating" issues were no different than any other RX8 he has worked on in the past.

So, bottom line, I'll just drive the crap out of it, watch the eng temp guage (or maybe get an aftermarket guage) and if it doesn't go past midpoint don't worry about it.

I do appreciate all the feedback and advice I got from you guys. I did soak it all in. It was very educational and informative. I'll just continue to monitor the website and learn how to care for by black beauty.

Cheers,
Jim Outlaw

 

Sounds good Jimmy. Keep your eyes on those temps.

Paul.

 

And..................change your oil when you should, keep it topped off, and keep those oil receipts!

 

Roger that

 

I hope they didn't charge you too much to do that, I haven't changed the thermostat on an rx8 yet but I hope it's about the same as most other vehicles.

 

Yeah Reaver, it would have been a royal PITA to change. There's just too much crap on top of the engine. I drove the car yesterday in denver when it was 91 degrees. At one time in traffic the needle started creeping toward the 3/4 mark. I finally broke down and called THMotorsports and ordered the Mishimoto radiator. It was $250. My mech at Japanese auto will install it for $300. I know I've spent a lot of money but dammit I want it right. I should have ordered the radiator up front. Oh well, lesson learned. I'll watch them do it and make sure the rubber bumpers on the side are put back right, etc. These guys are really good and very dependable to get the job done right. It's comforting to know the fans are working right though. That's an expense I didn't want to deal with. Everything else on the car is perfect so this should end my woes It sure turns a lot of heads when I drive it.

 

Be careful that they re-install the OEM fan block off foam with the new rad...otherwise you may end up with worse performance than the stock rad

If you are overheating at 91 deg ambient you have a problem....

For $300-400 you could buy an Accessport and have the FAN-ON temp lowered from stock and end up with more cooling than you will et from the new rad....

Just my 2 cents

 

Thank you for your two cents. I have to agree.

I'm running around in 95 degree weather(albeit at sea level) and even if I didn't have the mod to lower the temps(which I do have), I would be nowhere near that high.

It's extremely hard for me to get to 210-215 if ever............I mean I gotta be at 7-9k rpm and just ragging the thing for a long @ss time.
I think something else is wrong, I just am not sure what?

Supposedly water pump, thermostat, and fans have all been tested out, so what the hell is left?

Could altitude really make that much of a difference? Running leaner due to less air and therefore hotter?