I have the same thing, every so often if im heavy in the throttle the light will come on for around 30 seconds then go off,

coolant level looks fine

 

Sensor..............get a new bottle, take it out and attempt to clean it, or unplug it and check the level often.

 

Unplug the sensor and check coolant often, the coolant sensor is basically a POS like the coils.

 

Often? Don't let the presence of a level warning light make you think there's something special. Just check it every now and then, like any other car.

Ken

 

Just replace the whole resevoir from Mazmart. I had the same problem and had to replace the whole thing. No problems ever since.

 

That would require money, unless the car is under warranty i would just unplug it as well, whats the point in spending the extra cash to fix something that is relatively pointless in the first place? Now if its getting fixed for free then its worth it but anything over say... $50 for this wouldnt be worth it IMO.

 

My coolant sensor warning light now behaves like a second redline warning light lol. On 2nd reservoir tank with 26k miles.

 

Try the cheap fix first. Locate the sensor, are the wires attached or do they plug on to it . If the contacts are dirty there will be no electrical connection and thus no signal and the lite comes on.

 

^..............wrong Bob! It works the opposite. If you had terribly dirty connections, you would never get a light. When the float falls or sticks at the bottom of the tank, the reed switch closes and makes the connection(illuminating the light), so if it did that and you had dirty connection(s) at the connector(enough to make it no contact), then it still wouldn't light up.
If you unplug the sensor(it's a connector at the left of the bottle BTW) you will NOT get a light, you will just loose the ability to detect if coolant is leaking anywhere in the system, so you have to keep an eye on it.

 

here's my coolant light dilemmas..

Since I bought the car 3 years ago, the light would pop on very randomly but then shut off after either dropping down to idling revs (when just cruising) and after 30 seconds or so when i'm getting on it. I have talked to a ton of other 8 owners plus dealers about it and they all said it's normal. This is not the dilemma....

the problem is I had my oil changed 2 weeks ago at the dealer and ever since it comes on all the time. no difference if i'm cruising at low speeds, high speeds, mid rpms, high rpms or just simply sitting at a red light. I called the dealer and they said that it's normal and to just check the coolant levels and if I had a leak. But, wouldn't they have noticed a leak when they changed my fluids? And I would assume they would have put the proper dosage of coolant in the car, but I still checked and it appears to be fine. I want to know what happened after this specific oil change!

It's a new dealer for me, but I doubt that's the issue because they on top of their sh*t. Could it be that the guy doing it knocked something out of whack! PLEASE HELP! I hate having that F*ing red light in my face all the time...

 

/\ Having your OIL Changed has NO correlation with your coolant light or level whatsoever, it is purely coincidental.

I suggest you read the thread(s) and posts on this issue, there is more than enough information here....do a search.

IF the Wiring Connection Plug (to the left of coolant bottle) was disconnected 'by accident' you would have NO dash warning light.

These are connections that can not be knocked loose accidentally.

 

just as a quick side question...is there any particular coolant that is recommended for the rx8? or are they all pretty much the same.

 

DH............Look at the radiator cap or your manual for the car.....jeez......Mazda recommends, FL-22 long life coolant, but poke around and you will find that some use others and various mixtures.
Saying." I don't have a manual" is no excuse since it's a free download.
http://www.mazdausa.com/MusaWeb/disp...earHome.action


M Theory............pure coincidence. Really, it is. If it bothers you, you can either get a new bottle($160.00 at Mazmart), or unplug it as Ash has said!

 

Ok I can chalk it up to being pure coincidental because I know changing the fluids doesn't have anything to do with the light I just find it odd that it's coming on so often now. Maybe disconnecting it will just have to do.

 

It's a computer malfunction of the coolant sensor. The sensor is located inside your coolant tank. The whole thing has to be replaced if you want your coolant sensor to function properly. This happened with my car earlier this year. The light would go on and off usually on the highway.

The faulty sensor problem is quite common with the RX-8.

 

I just got my 04 with 59k and new motor at 55k. I found the connector disconnected which didn't thrill me. Plugged it in and the low coolant light stayed on with bottle over Full mark by 1/4".

My owner's manual warned: "Low coolant" will tell computer to not allow engine to operate fully at high speeds. So this would suck. Not having owned this car long enough to know just how fast it is how do I know the performance isn't hampered by the unplugged float switch on top rpm range?

Also when I went to remove the reservoir to clean it the plastic tit broke off the top of the radiator as it was totally decayed and brittle. Brown color plastic means junk just like my old Miata.

Ordered a new reservoir and an all aluminum radiator. BUT I still wonder about the performance interference via the computer?

Thanks for any info.

 

^......Hmmmmmmmm..............well, I will research that, but can you tell me specifically(by page number) where it says that?

I found

"To protect the engine, when the
engine coolant temperature is low,
the engine does not run at high
speeds. The fuel supply will be cut
at an rpm lower than the red zone."

That is NOT the same thing as you were talking about.



Sorry about the rad tit.........that seems to be gaining in happenning as these cars get older.

 

I stand corrected. You certainly are right. In my haste to learn this car I apparently read out the word "temperature".

Thank you for the clarification.

 

No problem, I just wanted to be sure and not have incorrect information start to get spread around. There's enough of that on this site ............from time to time.

 

Okay so I got a purdy new reservoir and a brand new all aluminum radiator.

I had soaked the old reservoir for 3 days in a strong bleach solution and it cleaned up the plastic tank pretty nice. The float will not float but moves easily when empty and shows proper operation on the reed switch on my VOM. Before it was actually stuck to the bottom of the shaft and had to give it a whack with my hand to make it move. After cleaning it flopped up and down nicely almost as good as the new unit. Filled it with water and it won't float!! I'll soak it in vinegar for a month and see if that helps? I doubt it. I think the s.g. gets changed due to heat or minerals or whatever after 7 years.

The new black reservoir float sits on top of the fluid about 1/2 out of the antifreeze. It flops freely up and down quickly when empty just by tipping.

Anyhow the new unit worked perfectly until I took the car out for about 1/2 hour of spirited highway driving to become more familiar with my new car. The low coolant light came on!! I had to poke the float with a long plastic zip tie and it finally floated back to the surface. Appears to have issues with jack rabbit starts and stops more than anything else. Maybe too much room for sloshing in the tank when filled to proper levels? Might get cocked at an angle due to loose tolerance on post?

If it happens again I'll just unplug it and feel like an idiot for having spent $110 + tax S&H for a clean plastic bottle.

Oh, and thanks to the guy (on another thread) who actually cut one of these open to explain exactly how they work!!!

 

Interesting.......one of the things I had come up with is that the buoyancy of the float changes over time and that's why cleaning doesn't appear to fix it for long.
I think you just confirmed that fact.

I'm really surprised the new one did it that fast.
Mine has been in for quite awhile now and I redline 2nd and 3rd every day(twice a day) and mine has not come back on. Did you check the level upon your return? Maybe with the new bottle it needed some after the spirited drive?
Do you happen to know what revision of the bottle you were given? "M" is the latest that I am aware of.

And...............You're welcome(if it was my thread you are eluding to?)

 

Yes in fact it was/is your excellent post....I recognize your car - same color as mine.

Yes the number on the new one started with an M. It hasn't done it since under any reasonable driving even under speed but I'm not certain if it was my "stability off" hardest possible launch- then flat out to 4th or my "let's see just how good these ABS brakes are?" stop following it? I think the double extemes of things I won't ordinarily ever do again is what got it sloshing? I just wanted to see what the car would do (on my MC testing road) since it is new to me and I wanted to see it's limits which are impressive.

I will be autocrossing it next weekend for the first time so I'll see what (if anything) happens then with all that sort of smooth jossling? I just got a new batch of vinegar to see if over time the old float will return from being a stone? Just as a matter of curiosity now. I'll post any results after a month.

I have noticed if one slowly removes the reservoir cap with car up to temp and engine off the coolant rises about 1/4" in the tank past the full mark so pressure matters along with temp. Perhaps I should change my cap too as it's probably 7 years old.

 

If you installed a brand new Overflow Tank N3H1-15-350M it has a new cap attached.

 

My coolant-sensor failed at 20,000 miles replaced under warranty by Delray Mazda no
issues - N3H115351G . Worksheet said BULLETIN #01-006/09

 

That's what it said on the Mazda dealer order site too but someone must have hooked it as it was not included with the tank. I'll have to send them a moan!!

Thanks.