Overheating coolant
 

Hi everyone.

Many apologies if this has been covered elsewhere.

I have a 04 rx8 231hp. Manual 6 speed.

I'm in the UK.

Basically, my engine coolant temperature gauge is showing the car over heating. It doesn't go all the way into the red, but it moves from the middle to about 2/3 of the way towards the red zone. This starts to happen when I rev the car past 5k revs per gear change...... If I stick her in 6th gear and drive at 50mph low revs the temp gauge goes back to normal.

I have checked the coolant, there is plenty in there. The water pump seems to be working as it should. The radiator kicks in when it should and also works when the car is turned off (know that's normal).

I'm just a bit stuck, as the coolant level is fine, water pump is work and the fan is working.

Does anyone have any ideas?

I'm running on Mazda original oil too if that helps?

Only modification I have is a cat back stainless steel exhaust.

Thank you all in advance.

Liam

If the needle is moving, that is bad. Even if it just moved a little bit, it is possible there is already engine damage. By the time the needle moves, it's already into critical temps. Repeating the it over and over again is nearly guaranteed to have engine damage.

Sounds a bit like a thermostat failure. Expect this to be a big deal, you may be pleasantly surprised if you escape with only minor repairs.

Thank you for the quick reply :)

What do you suggest I do? Replace the thermostat?

Thanks again!

It sounds right. Keep in mind it's just a guess on my part though. If the thermostat is sticking, it's likely that there are more problems with your cooling system. If I was in your shoes, I'd replace the thermostat, all coolant lines, radiator, and coolant bottle. Yeah, this is everything but the water pump. I might even replace that too if it has anywhere near 100,000 miles on it or more. The only reason that it's not an automatic for-sure replacement is that they don't often fail (it's just a pulley driven impeller), and if this damaged your engine a replacement will have a new water pump on it anyway.

Ok, thank you so much.

I will go and buy a new thermostat tomorrow and replace it as soon as possible. Unfortunately the car is my only method of transport at the moment.

Just had a look online and a replacement thermostat isn't too expensive so I guess that's a plus.

You are a very helpful person, so thanks!

I had that symptom with my previous car not an 8 though
and its the thermostat.

Thank you.

I have reserved a new thermostat online and will collect it tomorrow.

Fitting it..... Should be great fun.... Cough cough...

:)

+1 for the thermostat. Keep us updated...

I collected the parts this morning. New thermostat and new coolant.

Going to call the garage on Monday and book it in for the thermostat and coolant to be change.

Fingers crossed this solves the issue

Thank you all for your help.

Will post a update on Monday

Hey everyone,

Sorry its taken awhile for me to get back to this.

I got the thermostat changed for a new one, and also had a full engine coolant change.

Its fixed the problem :) Temperature gauge doesn't move at all now.....So i can drive the car like its meant to be driven......in the high RPM range :)

Thank you for everyones help!

For people in the UK. I got this fixed at a RX7 & RX8 specialist called Super 7 Autos in Worthing, East Sussex. I would highly recommend them.