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Overheated RX8

Posted: Wed Sep 16, 2020 1:30 am
by nox
Hi folks. Sadly my RX8 overheated on the M4 on Sunday and had to be towed back home. RAC man diagnosed it as blown head gasket

Anyway what does overheating do to the renesis? I’m thinking of putting the car out for anyone who needs parts/new project/etc as last resort. I did have to drive it for about 2 miles to park and wait at a service (advised by RAC) and the didn’t sound bad.. but unless looked at deeper, won’t know obviously...

8 years of joy but sadly has to go looks like.. Mine is a 231 Titanium Grey. Mostly stock. Apart from d585’s and custom exhaust from Carl Hayward. Engine rebuilt 2017 by Chris at Apex Rotary.

Cheerz!

Re: Overheated RX8

Posted: Wed Sep 16, 2020 6:03 am
by Nickp47
I had one overheat a few years back, it destroyed the coolant seal which meant a rebuild was required.

Re: Overheated RX8

Posted: Wed Sep 16, 2020 8:50 am
by Nerdstrike
Mine boiled up years ago after the fan seized. It survived and ran fine for years until I sold it. It may be ok, depending on the nature of the failure. If yours overheated in slow traffic you might have a chance. I can see how an overheat under power would suggest a much more dramatic event.

Re: Overheated RX8

Posted: Wed Sep 16, 2020 8:56 am
by New Duke
Normally if it overheats the PCM should cut the throttle to protect the engine. I've done that a couple of times. But then it should be fine once cooled a bit. If Mr RAC couldn't restart it then maybe it had failed to cut the throttle in time.

Yeah overheating can cause anything from absolutely nothing to a rebuild. If it sounds fine, drives fine and has no leaks then it's probably fine.

Re: Overheated RX8

Posted: Wed Sep 16, 2020 9:54 am
by nox
He actually restarted it and it sounded fine. There was a slight whining noise. He added coolant and then used a device that looked like a test tube with blue fluid in it. I believe this is to test for gas leakages in the coolant? That’s where he said head gasket is gone. But the 8 doesnt have one right?

Re: Overheated RX8

Posted: Wed Sep 16, 2020 10:20 am
by warpc0il
If there's exhaust gases in the coolant - which is what his tester was looking for - then it's going to be a water jacket seal failure. That was mean a strip and rebuild.

OTOH it could appear to overheat, blowing coolant and steam all over the engine bay, just from have a loose or damaged cap on the header tank.

You need to get it checked by someone who understands rotary.

Is Luke around?

Sent from my SM-G800F using Tapatalk


Re: Overheated RX8

Posted: Wed Sep 16, 2020 10:23 am
by nightfire10
The coolant seals are our head gasket as such, dave should be along with his knowledge to confirm that if exhaust gasses are found in the coolant its rebuild time unfortunately

Sent from my VOG-L29 using Tapatalk


That was quick

Re: Overheated RX8

Posted: Wed Sep 16, 2020 10:31 am
by New Duke
EDITED - Set straight by Nick :salut:

Re: Overheated RX8

Posted: Wed Sep 16, 2020 11:53 am
by 13Black
To be honest I doubt it needs a rotary specialist - they'd be no more clued up than a regular mechanic when it comes to checking for exhaust gasses in the coolant - they'll use the same tool and there's no user input / deciphering required. If you can read a pregnancy test, you can tell if a water seal has gone.
If you saw him do the test and the blue fluid turned yellow, it needs a rebuild.

Re: Overheated RX8

Posted: Wed Sep 16, 2020 1:22 pm
by bigpete8
Buy one of these and test it yourself...

Re: Overheated RX8

Posted: Wed Sep 16, 2020 2:25 pm
by 13Black
I should hope that we can trust the RAC to do a simple test - for half the price you could stick some K-Seal in it and possibly get some more miles out of it (though not without the usual caveats).

Re: Overheated RX8

Posted: Wed Sep 16, 2020 5:05 pm
by stewartm
Others might have a more informed opinion to say whether this is correct/worthwhile - but leaving the car to stand for a few days or so if you have the time and seeing if you have trouble starting it, might also reveal the likelyhood of a water jacket seal failure. My first 8 would easily overheat under load AND if left for a while would struggle to start - the theory being that under load escaping gas would cook the coolant and whilst stood, that coolant would seep back into the chambers.

Re: Overheated RX8

Posted: Wed Sep 16, 2020 8:04 pm
by nox
Thank you everyone. Great ideas and thoughts. I will try and follow some of these in the week-end. Once again, thanks ever so much for taking the time to reply. =D>