weird coolant leak! need help!!
 

Hello all,

This is my first post.

And i really need some help!!!

Ok so here is the problem.

I have a 05 rx8, I "think" that i have a crack in one of the coolant hoses.

if i drive normal (not going over 90mph) the water temp stays below half way
(as is always does)

but if i go over 90mph it starts to stedly get hotter i have only let it get 3/4 way to "HOT" before i backed off....once i back off the gas and back down to 80mph it cools down back where it always is.

if i drive it hard and the coolant temp get anywhere close or past half way,
thats where i find the leak... it seems like the coolant that is leaking is hitting the fan and blowing on to the engine bay covers and underneath.

If it is the hoses does anyone know how much that might cost for Mazda to replace?

please help!!

Doesn't sound like a coolant leak, sounds like you are boiling over your radiator. The overflow puts the water right on top of the fans. First thing I would try is cleaning your AC condenser coils/radiator just wash em out with a hose.. You should not be running that hot normally. Next thing you can try is a coolant flush then replace your coolant. Also try replacing the radiator cap. If you keep boiling over like that you will end up blowing a coolant seal. Ask me how I know.

Ok i will try that....its just weird because the radiator and the coolant tank are both only 2 months old. and just now started to do this.

and when you boil over the radiator where does the coolant leak from?
the overflow hose on top of the coolant tank? if so that might not be the problem because every time coolant leaks that hose is dry.

sorry to ask so many questions but,
what cause a radiator to boil over?

Thermostat would be my first choice...not opening completely or stuck part way open. Does it heat up normally when cold...or is it a bit slow?

From cold, it heats up just fine takes about 2 mins of driving then its right up to below half way on the temp gauge. and it will stay that way until i start driving it hard. then that when it starts to get hotter.

If your stock temp gauge starts to move at all...you are already WAY too hot...it doesn't budge until 235 degrees.

Well i will diff keep that in mind when some z car zooms around me,it will take every bit of me not to run him down.

But what i am trying to find out is why does it only leak when the car is driven hard?

maybe its a really small crack or something and only when it builds up a ceertin amount of pressure it will leak?

and if so would that make it get THAT hot?

if it is a bad thermostat would that cause a leak?

The first thing you should probably do is verify that both of the fans are turning on.
If they aren't turning on, then that would explain why the temp gets so high.

Is all of this with the A/C on or off?

BC.

Its leaking cause its overheating

not overheating cause its leaking :)

Usually high speed overheating isnt the fans...they usually arent on at those speeds anywau

Well i do know that at least one of them is turning on i will have to check it when i get home.

now do keep in mind that the car has never reached "H"/HOT the hottest that car has ever been was 3/4 at 140mph once i saw that i back off,and went right back down to below half (i know that is still HOT but still) i am going to take it to shop tomorrow morning and see if i cant get this solved once and for all.

thanks for all the help guys

if this doesnt get fixed tomorrow then i will be back on monday!

Have the cooling system pressure tested.

Another thing that causes high RPM overheating is a collapsing lower radiator hose......

I can relate to this problem, I was having trouble with my car running hot and I had a leak I could never find. My solution was more of a shot gun approach, I just replaced the entire cooling system. I have an 04 with less that 50k miles on it. The hoses where in horrible shape and where probably collapsing under high load high rpm conditions. The thermostats in these cars fail closed rather than open, and the water pump just can't keep up in high rpm conditions. I've since replaced my t stat and water pump with mazmarts, radiator with a BHR radiator, coolant resivoir, and all coolant hoses. My thread is here https://www.rx8club.com/series-i-trouble-shooting-95/redline86s-coolant-issues-plus-major-summer-project-218810/

I'd check your fans first to see if both are kicking on. Start simple and work your way through the system. If the hoses are in bad shape I'd think about replacing them with silicone ones. If you are only having problems when a load is put on the engine I'd be leaning towards a bad t stat or collapsing hoses. Also check the seal around the water pump for leaks, those seem prone to failure.

While you're at it, extend the reservoir's overflow hose to exit near the bottom of the engine bay. Stock, it sprays onto a connector for the power steering which will corrode it and possibly result in some very expensive repairs.

I'll say this once: 140 mph and racing with other cars on public roads is irresponsible and asking for disaster. That's what race tracks are for.

well guys turns out it was the t.stat it was stuck half way open and building pressure there for causing be to boil over.
just to let yall know i was at ATL motor speedway when i was going 140+ not on public roads.
thanks guys for all the help!

Great it worked out for ya...

Had the same problemz a few days back.. Had to replace mazmart thermostat back to stock 82 degress... Sad...

But still having some leak somewhere as i had top up full but barely 2 days later, it has gone back down to almost low level... Coolant flush has alreadyz been done...


Now might be the hoses but they are silicone Samco hoses which are just less than a year old... Waterpump hose... Anybody got a direction or a pic to it?

Sure it's not leaking into your oil?

How is that suppose to happen?

Ask 9krpmrx8, he has had that problem. I don't remember the details but he had the oil analysis to prove it.

Ok here we go https://www.rx8club.com/series-i-tech-garage-22/possible-new-renesis-engine-failure-theory-210194/page22/ scroll down and he mentions it, I know he wen't into more detail elsewhere I just can't remember where.

Much appreciated bro... Cheers!

Did you go ahead and extend the overflow tube as HiFlite recommended?

This sounds very similar to my problem I had sadly after my little crash that happened, I spun out on a wet road and hit big pot hot in the woods managed to get the car working again but the repair shop I took it to charged me 2400$ to fix and paint the car ever since I got her back all these problems are happening.

Also hoses are quite cheap I found all 3 for around 150-200$ range

I’m sure he appreciates you replying 8 years later.