you guys should all listen to Mazsurfer on this. He knows exactly what he's saying and couldnt be more right. He performed the most in depth investigation into that Reed switch I've ever seen :O

Although replacing the reservoir is an option, for some. It does not fix the poor design and best odds are the problem will eventually return, sooner or later.

 

My battery light...opps... I mean coolant sensor also went at 62, 000km or so and was just replaced. All seems well for now.

 

So I have a new reservoir bottle and it's filled to the right level.

Now every time I pedal to the floor in second to redline and then back off shortly thereafter the light comes on and stays on. But after about 5 minutes of driving it goes back off. Slosh after g forces stand the water to the back of the tank causing the magnet to drop? Tomorrow I go autocrossing so will see what happens then?


Also a pix of what happens to plastic factory radiators after 7 years. They turn brown and are very brittle. Note new Mizu aluminum in background. What an improvement!!

 

^................This is bothersome with such a new tank.
What is strange is when I got my new bottle(probably over a year ago), I used my old cap as I had painted it and didn't feel like painting the new one.
I redline 2nd and 3rd twice a day and since my new bottle with old cap..............no issues.
Your latest post has me scratching my head a little bit. What you described in that post is EXACTLY how 95% of us first see the issue and continues to get worse until on all the time. I know you know that, but I'm just saying.............is it possible you have something else going on as well? Maybe your cap as you mentioned?
I have the "new" one that came with my bottle if you want me to send it to you. Shoot me a PM and I'll send it.

 

So here's an interesting twist.

I spoke to the dealer about my 8 and the coolant light (same symptom everyone else has posted 1000 times on this thread).

Dealer says he's aware of the problem and my extended warranty will likely cover it, but that it's very common for the repair to actually cause the connector to the radiator to crumble.

Once that happens, the radiator has to be repaired too which WON'T be under warranty since it's still technically working fine.

This logic confounds me.

Anyone else fallen into this trap and ended up with an $800 repair bill?

 

Never heard of that. I replaced mine with no problems

 

lol same. ^

 

i think nycgps referenced that earlier today somewhere that if the dealer is not careful they can screw up the radiator and end up needing to replace that

i think that was in a rad hose repair thread but who knows wtf these dealers do sometimes

 

Yeah, that reference is because if you aren't careful you can break the plastic connection of the hose fitting at the top of the radiator.

Anyways guys..............there is some somewhat new info in my "Coolant Bottle Greatest Secrets" thread. https://www.rx8club.com/series-i-trouble-shooting-95/coolant-bottle-greatest-secrets-revealed-182793/

Failure has pretty much been confirmed as the float losing buoyancy over time. There is a relatively new TSB out on it, it can be found in my thread........and................if you have a July 05 build date or later, you can just buy the bottle and save the sensor from your old bottle. The float comes with the bottle as it's integral and you can't get that out.
Bottles on sale at finishline for $99.00 with sensor, $79.00 without(if you don't need it). http://www.finishlineperformance.com...cat=336&page=1


NOTE: Those prices are WITHOUT a new cap as well.

 

I give kudo's to that service manager!! Mazda plastic tank radiators are crap on longevity AND expensive even tho' they cool properly. I found a fantastic Mizu all aluminum 3 row for $250 delivered free online. (BTW my 99 Miata did the same thing only the whole return tube crumbled when I tightened the leaking hose making it an emergency replacement.)

If your plastic radiator tit is discolored (brown) it is brittle and has virtually no strength. There is virtually no way to remove the reservoir without snapping it off if it is bad. The bad is mostly hidden inside the hose. My car is 7 years old and that tit actually crumbled like peanut brittle a 1/8" above the tank leaving no way of even a temporary repair. Of course you won't know that until you try to remove the reservoir and put any motion on that small hose.

What you need to do is replace your radiator yourself (out the bottom) and then go see the dealer again for the free reservoir. If your car is over 6-7 years old it is a time bomb anyhow.

You can easily live without a coolant float idiot light (unplugged) but you will be walking if you don't replace the factory radiator in time.

 

damn my keeps coming on and off every 5 minutes.

 

So are you bitching or want help?
If help, then go here.

https://www.rx8club.com/showthread.p...59058#poststop

That will throw you to a post at the bottom of this thread that has the latest info, and will throw you to another thread that also goes into more detail.

 

Mine is failing too.

Seems to be a serious desire problem.

Engineers desire a coolant level sensor. But then they make it out of cheap plastic that fails before the actual rubber of the hoses. The sensor ends up being more troublesome than the hose rupture that announces itself in a much easier to read manner than an idiot light in the shape of the Lincoln memorial.

I had an XR4TI that had the same problem, and the same solution. The floater had a magnet in it that rusted out as the plastic aged. The fix was a safety pin through the wiring.

 

This may be a little off topic, but where did you get your Mizu radiator from, and was it a direct OEM replacement, or do you have to cut anything to make it fit? I have an '04 and thinking of replacing the stock radiator.

 

i have the same problem here, my low coolant light keeps coming on but i was wondering, if i unplug the sensor will the light stay on?? cuz it's really getting on my nerves

 

no.

 

You may have a defective sensor if there are no leaks on the coolant system.

 

Hi all,

If I disconnect the sensor and I monitor the engine temp using the regular temp gauge on the dash and visually check the levels regularly will it be OK? The cost of a new bottle just to get another sensor which will in all probability go again is extortionate!

 

No, our gauges are dummy gauges so to speak including the oil. You won't see the temperature gauge move at all hardly other than from nothing to the same place it always goes after a few minutes of running the car. As for if it overheats, I doubt they will do much to warn you since they again, are not accurate.

Many of us go buy aftermarket gauge clusters such as Racing Beat and install oil pressure/temp along with water temp gauges so we can actually see what they're really reading.

 

In addition to what the previous poster said, yes you should be fine if you *visually* inspect the coolant level every so often. I've had my coolant level sensor disconnected for a few months now.

 

My coolant sensor has been like that for a while, it just goes on when I push my car hard, yes I have coolant I'm sure.

it happens too often that I don't even give a **** anymore.

 

Yep, eventually the float will loose all buoyancy and it will be on 100% of the time.

https://www.rx8club.com/showthread.p...32953#poststop


Dave

 

Hello, I have rejoined - my previous ID 'died' a few years age due to inactivity...

I have a 2004 RX-8 with about 75000 miles and a new motor with about 2500 miles on it. Just recently, after the installation of the new motor, my coolant light started coming on. I have read a lot of these postings and even the service tech at the dealer I use told me there was a lot of discussion on this website about the coolant tank sensor. It is just curious that it just started after the motor was replaced. I check my coolant level as well as other fluids weekly and all appear to be OK. After reading a bunch of the posts, I guess I will just continue to watch the coolant level in the tank. Thanks for everone's input on this site.

 

techster - was your coolant bottle replaced as well when the engine was replaced? I'm going to assume it was not, as this seems to be an issue that comes up in time, I'm not sure that I have seen any threads or comments on this happening on a brand new bottle / sensor...

 

No - all that was replaced was the engine core. Everything else was re-used. I did have some new spark plugs installed that I purchased separate from the engine work. At suggestions noted in a few posts, I added some coolant last night - we will see if that makes a difference....