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Radiator warning light on

Old 07-19-2015, 09:44 AM
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Radiator warning light on

Hi To you all, I recently bought a 2004 rx8(uk), the previous seller said it had hot start issue, however after running it, the temperature displays midd way ie normal, and starts ok maybe I was lucky as this put off other ebay buyers so got it for 940 gbp, got sat nav boss 6cd interchanger, 18 inch alloys, parking sensors, and even had complete flat tyre original kit. having said all this when checking the fluids all seemed ok bar the coolent level which looked very low, however there was no warning light on, I completely filled it up with fresh coolent,and took for run, the radiator red warning light came on, and wont go out, I have found the information very useful as supplied by other members on this forum, and note that the magnetic sensor can sometimes stick, so I will shake it and see if this works, I also intend to syphon out some fluid and see if the problem is due to overfill, but I cant see why this would matter as there is over spill exit for excess fluid. I have a ford Mondeo there is a mark on the water tank indicating correct fill line, is there a mark on rx8 bottle, I cant see one? I had an rx7 20 years ago, and that had teathing troubles to, guess thats what makes this kind of car very interesting, regards to all.
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Old 07-19-2015, 11:50 AM
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You made a mistake by filling it all the way to the top. Siphon some of it out. There is a full mark but it is difficult or impossible to see on an older tank. The full mark is approximately half way up the tank. I can't see mine any longer but I check it with my little finger. When I stick my little finger as far into the coolant tank as possible (with the coolant cold, of course), I can just barely wet the tip of my finger. That tells me it is properly filled. So if the add coolant light is on and the coolant level is ok then you can assume the magnetic float sensor is bad. You have three choices then. Ignore the coolant level light and check the fluid level frequently; disconnect the fluid level sensor wire and check the fluid level frequently; or replace the coolant bottle and level sensor.


Congratulations on your purchase and welcome to the club.
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Old 07-19-2015, 01:42 PM
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And if the sensor is bad, I suggest getting a replacement tank with the revised sensor. "Checking the coolant level frequently" isn't good enough. Because if you experience a sudden loss of coolant while driving, you won't know until it's too late.
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Old 07-19-2015, 04:06 PM
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remember the coolant level sensor and overflow bottle are sold as one part. You can't buy the sensor, which has a history of failure, as a separate part. Mazmart has good price on the bottle and sensor.
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Old 07-23-2015, 12:25 PM
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Thanks gu.ys for information
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Old 07-23-2015, 11:00 PM
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Originally Posted by New Yorker View Post
And if the sensor is bad, I suggest getting a replacement tank with the revised sensor. "Checking the coolant level frequently" isn't good enough. Because if you experience a sudden loss of coolant while driving, you won't know until it's too late.
If you experience a sudden loss of coolant whilst driving, it's already too late.
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Old 05-15-2016, 09:36 PM
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I disconnected the sensor wire
No problems as coolant level hardly changes.
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Old 05-16-2016, 01:03 AM
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Originally Posted by RC1998 View Post
I disconnected the sensor wire
No problems as coolant level hardly changes.
Bad, BAD, move, and BAD advice.
If you develop a leak, say a hose, or some debris punctures your radiator, your coolant level will change and your car will overheat probably before you even notice the semi-useless temp gauge move into the hot zone.
Risking a $5k+ rebuild vs a $150 proper fix is silly, lazy, or cheap, and advising others to do so is irresponsible.
I would advise anyone to NEVER disable a warning light.

Don't think it could happen?




A 1" long screw that I found wedged under my foglight.
I was lucky it hit there.
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Old 05-16-2016, 07:31 AM
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I have to agree with BigCajun here. Yes you can get by with just checking the coolant level BUT the risk of missing an overheated engine is really too great. In my case ,after one month of worry, I just bit the bullet and bought a new bottle and sensor.

I still plan on going further by adding an OBD2 reader to really be able to keep tabs on temps as I am getting a rebuilt engine put in this next week.

Last edited by gwilliams6; 05-16-2016 at 07:34 AM.
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Old 05-16-2016, 10:36 AM
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Just to let you know, when replacing the coolant overflow/sensor, you will often break the part connected to the radiator. Its a plastic part that becomes brittle with age and then you need a new radiator. This happened to me. I've heard others advocate for cutting the hose with a razor and "peeling" it off the nipple.
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Old 05-16-2016, 03:18 PM
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Correct CoolT, its that nipple that breaks at the radiator , and then you need a whole new radiator. You need to carefully slice the old hose and peel it off, and then put on the new hose. Forgot to add that to my post, thanks.
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Old 05-16-2016, 04:13 PM
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Originally Posted by BigCajun View Post
Bad, BAD, move, and BAD advice.
If you develop a leak, say a hose, or some debris punctures your radiator, your coolant level will change and your car will overheat probably before you even notice the semi-useless temp gauge move into the hot zone.
Risking a $5k+ rebuild vs a $150 proper fix is silly, lazy, or cheap, and advising others to do so is irresponsible.
I would advise anyone to NEVER disable a warning light.

Don't think it could happen?




A 1" long screw that I found wedged under my foglight.
I was lucky it hit there.
^
I said this a few posts back almost a year ago. It's as if I never wrote it at all!
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Old 05-16-2016, 08:40 PM
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Originally Posted by New Yorker View Post
^
I said this a few posts back almost a year ago. It's as if I never wrote it at all!
People don't read more than a few posts it seems.
This is one of those issues that keeps cropping up repeatedly, and people keep popping off with unplugging the sensor as a solution.
I'm surprised more don't recommend the electrical tape 'solution'.
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Old 08-16-2017, 12:36 PM
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I have the same problem was thinking about the rx8 perforemance AST v4 with the sensor and fan controller. Is it a waste of money at $300?
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Old 08-16-2017, 12:38 PM
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Hmm I see it for $110 with new sensor. I can buy fan controller separately for $110
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Old 08-17-2017, 02:26 AM
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Just disconnect it and check the Level every week before you drive. The car will be completely fine as Long as you turn it off before it gets into the red Zone anyway, contrary to what many may say. I had my car Smoking after a trackday and thats not because the engine overheated but the exhaust and cat glowing (yeah currently replacing that bad kitty).
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Old 08-19-2017, 04:11 PM
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Originally Posted by New Yorker View Post
And if the sensor is bad, I suggest getting a replacement tank with the revised sensor. "Checking the coolant level frequently" isn't good enough. Because if you experience a sudden loss of coolant while driving, you won't know until it's too late.
Revised sensor? I couldnt find anything on this? Is that just from a newer model? thanks
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Old 08-20-2017, 02:57 AM
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Originally Posted by TomX8 View Post
Just disconnect it and check the Level every week before you drive. The car will be completely fine as Long as you turn it off before it gets into the red Zone anyway, contrary to what many may say. I had my car Smoking after a trackday and thats not because the engine overheated but the exhaust and cat glowing (yeah currently replacing that bad kitty).
if you see the temp gauge move on a rx8 you are already in trouble..

beers
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Old 08-20-2017, 07:48 AM
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RX-8 AST Closed Cooling System Upgrade

One way, albeit expensive, to get a revised sensor. I have it installed in my RX8, but then I am obsessive about my car. lol
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Old 10-09-2017, 09:41 PM
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Low coolant.

You will smell antifreeze before you ever notice the tinyest of leaks. If you don't know what hot antifreeze smells like you shouldn't be reponsible for a car. We never use to have low coolant lights just engine temperature guages or worse yet idiot lights. If you have a catastrophic loss of coolant no sensor is going to help you. Just shut the engine off as soon as you smell the antifreeze, if you know what it smells like. If not, like I said.....
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