Hit 132C/270F the other day due to a freakish mishap involving a stuck throttle. I shut it off just in time and so far everything seems ok. I am using McMaster-Carr inner coolant seals.

 

I pinned my Gauge once,due to not turning the Efan on after a HOT Start.
It went to 238 on the Rtek,But I noticed a bit of Steam coming out by the Overflow bottle and Pulled into a parking lot and shut it down.
It survived just fine,BUT let me tell you,I was Freaking out!!
So,needless to say I now have the Efan switched to Ignition,so that is comes on when the car starts.I have to keep my blood pressure down,Haha!!!

 

^ have you seen my thermoswitch writeup? IMO there's really no need to wire an electric fan to a manual switch or to ignition power.

 

Why leave something that important up to memory? Go with a thermoswitch.

 

Well the short answer is no. After the thermostat stuck and it overheated the coolant seals were already toasted.

 

Massive loss of coolant due to the lower rad hose tearing on the track. idk how hot it got, but I shut it off real soon after the low level buzzer came on. It was shortly after break in and she still runs like a champ, I was pretty worried though.

 

When I first built my engine, I had a slight coolant leak that I could not find. The light would come and go and it went on like that for a while. So like an idiot, I ignored it as I had no luck finding the leak. I went to go for a quick romp around the neighborhood and I got onto the main road and the light stayed on and the temp gauge went up to 6-7/8ths. I also had the autometer and IIRC it went over 240-250. I said FFFFFFFUUUUUU and drove home slow, temp stuck around that high but I made it back. I guess you get one overheat. After that I filled it up properly, and went crazy looking for the leak(s). Turned out it was the heater core return hose. I never found a puddle because it's right over the exhaust. I put a new clamp on it, and put it on as deep as I could get it. No more leaks and coolant light for well over 1 year now.

 

i have hit 139C with OEM coolant seals(customer's car whom the radiator fans weren't turning on and i didn't notice it) and about 125C with the mcmaster carr coolant seals in my FC(was running a manual e-fan switch at the time years ago..), the FD which reached 139C with fresh coolant seals didn't show any ill signs of coolant seal failure where my FC with the mc-master carr coolant seals started showing signs of internal leakage a few months later.

i have seen 2 customer's cars with OEM coolant seals that had liquified because they ran the car until it wouldn't run anymore, neither resulted in failed irons(luckily for them). i have no idea where they liquify at but i had originally assumed that they hit about 125C but after seeing the FD reach 139C i am thinking they can take about 149C/300*F before they liquify.

new OEM coolant seals can take ALOT more abuse than most people give them credit for, old 20 year old OEM coolant seals are much less forgiving. the teflon coating on the mc-master carr coolant seals also allows them to break their seal and be more unforgiving than i had hoped that they would, which is why i don't install them on customer's cars unless they specifically ask and i tell them the pros and cons. the only pro i am finding with them now is they are reusable, they however do not stay sealed for as long as the OEM coolant seals do, they also have a tendency to chafe through the teflon coating.

 

I have run my coolant temp up to 280* when doing a 'hot purge' procedure during conversion to Evans Coolant. Multiple times.

Rad cap off, no boiling.

 

in all honesty i have overheated many motors while burping the cooling systems on fresh motors and i don't even break a sweat, i just casually turn the car off and let it cool down naturally. if you try to assist in the cooling process is where irons crack and hell breaks loose.

if you feel the need to help, use extremely hot water, not cold. think of the engines like cold glass with warm water, they will shatter at any imperfection point as they warp.

 

Fortunately most of us aren't stupid enough to dump cool water on a hot motor. Most of us...

Anyway I always thought the overheat worry was a warped plate/housing. The warp causes the sealing surface to open a bit and let the coolant through. Looking at housings, why they never had a coolant seal groove like the iron boggles my mind. The Renesis has them I think finally).

 

another misunderstood fact is that these engines naturally warp as the rotor housings and irons expand and contract. there is almost always a gap between the rotor housing and iron, the coolant seals are compressed and are what seal the irons to the rotor housings and it takes ALOT of expansion/contraction to break that seal.

the myth that warped irons cause coolant seal failures is just that, a myth. as another interesting side note, notice there isn't a runout measurement for the rotor housings in the engine specs? because it isn't important as i noted. the warpage limit is mainly for oil seal control ring wear. if the irons are warped then the oil seals will work overtime as well as the side and corner seals causing everything to wear more rapidly including rotor bearings as the rotor "wobbles".

now i'm not saying that gaps between the housings and irons is good for the seals but there will always be some there, the coolant seals are designed to be able to withstand the combustion gases while the surfaces keep them cool.

 

Engine block to heater core hose (on drivers side U.S.) bursted. I was sitting at a red light. Light turned green and as I accelerated the low coolant buzzer came on. With tons of cars behind me and 2 more lights before I can pull into a parking lot, I just shut off the engine and coasted light to light, turning on the engine as needed to get to the parking lot.

Original engine @ 140k, it survived.

 

all the engines up to 1985 have coolant seals in the housing ,,13bt , 13b RE and 13b REW engines have them in the plates
rx8 has them back in the housing

if you want to know why they moved about ,, early ones had significant corrosion issues in the alum housing at the groove

-- the FC FD ones instead have corrosion issues in the plate,, or weak castings resulting in groove fail and are also limited in amount of face offs due to the groove being in the plate

mazda saw that two handicaps are worse than one,, and moved back to grooving the housing for rx8

as for the OP
-- with viton inner water seals my current engine has seen 250 F and beyond a few times
--- still going

with nitrile inner water seals and the previous engine i manged that also a few times , though eventually one of those caused a fail of the groove in one of the plates

having also previously done this with mazda water seals,, fresh ones ,, i found mazda seals not so forgiving

mmmaster teflon ones= no experience with them

 

Ahhh... I always wondered how HOT does the engine have to get to warp? Oddly, you do read a lot about engines burning coolant and failed seals and how overheating caused it. I think it goes the other way. I don't know. My only experience is a failed seal leads to overheat. I had bought a used j-spec and it turned out it overheated instantly drinking coolant all along the merry way. When I pulled the engine apart, I found a coolant seal was a mere powder in one spot and the iron had rusted a bit. The seal was completely dried up to the point where it turned to dust.

 

I overheated my first FC pretty badly when i first got it due to horrible wiring for the e-fan by the P.O. It was boiling coolant from the overflow, pegged on the stock s5 temp gauge... it ran fine for a few months after that until apparently part of the water passage collapsed driving to work one day. I've been paranoid ever since...

In the Lemons racing I've been a part of lately we ran a turbo FC in the last race down in Baton Rouge, it started getting hot on the last day, we were seeing 240* temps while driving. We just had to back off and baby it until it dropped and then we could run it hard again until it heated up. Ran fine for the full 24hours....

Previously in another race we had similar issues, one of the other drivers pitted in when he noticed high temps and it turned out that all the coolant had dumped itself or evaporated somehow.... no telling how long it ran like that but it was bone freaking dry when we popped the cap off the radiator.
Still runs fine, they ran it in another 24hr race two months later.

 

over a dozen times doing donoughts, high speed runs were you should be doing them. broken hose, radiator/no shoud/belly pan. no engine damage done.

missing a metering 10A fuse, breaking the alternator belt(with no air pump) and paying to much attention to my gf.... whilse driving around from about 9 to 10:30. didnt even know til the lights started going dim, then the heater core hoses exploded, warp'd the rotor housings(ruined the rotors) and was yet another 3 months the 10th AE would sit. temp? dunno the metering fuse was blown!!(due to short'd wire from steering rack)

 

the stock S4 gauge the 1st line by C is 65C and the line before the H is 110C...

my 76k FC has run hot since i got it, like 3/4ths on a hot day, for 2 years. its FINALLY showing signs of water seal failure.

 

It seems like with every seal there are people who are swearing by them and other people who have a bad luck story. The RA and Pineapple seals have their proponents and haters as well.

 

RA is the Mcmaster carr coolant seal in a package that sais Rotary Aviation.. set them side by side and you will see they are identical. RA doesn't make their own seals, i also doubt seriously that Pineapple does either, if you know who makes their seals you can buy them direct from the manufacturer unless they have a patent, RA doesn't which is why Mcmaster carr sells them to the public.

i buy OEM seals packaged by a japanese third party company from atkins, since mazda also doesn't make their own coolant seals.

the 20 year old seals are unforgiving because they lose their elasticity over time and fall apart, overheating allows more gases into the pocket between the rotor housing and iron to blow out the weak seal.

the main cause of failure though due to overheating these engines is due to the severe expansion and contractions from overheating, which results in cracked irons at the coolant seal walls. any rebuilder will have stacks and stacks of broken irons. i have at LEAST 30 irons sitting in the corner that have broken coolant seal walls, which i can repair and have a product coming out to help prevent the issue anyways, soon.

 

I was just rereading that prepping for my electric fan. When my rebuild is done I'll be adding a Ford electric fan and following your writeup.

To the OP. I survived an overheat. Was running one alt belt with deleted airpump. I snapped the alt belt getting on a 6 lane highway. I had the stereo up and heard/felt something. Before I knew what happened I blew the top off my OEM radiator. I got it off the road and parked and didn't do any damage beyond needing a radiator.

One thing that dawned on me with the plastic OEM radiators. Perhaps they made them weak for that reason? So that when you overheated you'd loose the radiator before you'd do engine damage?

 

they made them plastic because it saves them $1 to build the car, that is all.

 

The original engine in my TII did not survive.

The driver-side heater hose burst after coming off the freeway one night. Literally within seconds of seeing steam start pouring out from the hood, the engine shut itself off. I took a look at the water temp gauge and it was pegged, so who knows what temperature it was at; somewhere north of 220-230F.

After getting the car towed home, replacing the hose, and filling it with coolant, it did start back up. But after a few minutes of running, it would start spewing coolant into the overflow tank, and the temperature would climb excessively.

Upon tearing that engine down, we found the water jacket was cracked/broken in multiple places. Most of the engine was junk at that point.

 

Exact same thing happened to me. same coolant line busted. i started hearing the low coolant buzzer and i watched my needle go up RAPIDLY. so i shut it off. when the light hit green i started it and went and coasted. made it about 2 stoplights with the needle all the way up, origional motor with 160k on it. still goin!

 

Yes.