Overheating but only when it's 85+ degrees F and on a incline
 

Okay i have seen all the overheating threads but nothing sounds like mine.

I have a bone stock AT rx8 2005 With the mazdaspeed body kit. I live in Los Angeles.

It overheats when it's 85+ degrees and my car is going up a hill like Cold Water Canyon, Moholland drive, From Beverly Hills to The Valley on the 405 North etc.. Pretty much every incline that stretches for over a few miles. This is when AC is off too. Turning on the heater helps but that's not a solution. Temps drop when I start to go down the hill.

I've had an engine replacement at 94,000 miles. I have changed the radiator 3 times. I have changed the coolant reservoir 2 times. Everything I have is OEM and done at the dealership up until my 2nd motor warranty ran out. I have 120,000+ miles on my car now.

My car is fine in stop and go LA traffic. For those in LA you know how the 10 and 60 fwy is in the morning and early evening. It takes me 1-1.5 hours to go to work and going home it can take up to 2 hours and I only drive 23 miles. LA Traffic sucks! Reason why didn't get stick.

So what do you guys think is the problem?

Have you checked the fans to make sure they are both working? Driving uphill places extra strain on the car, the trans also which has its fluid cooled via the radiator. It's possible that during your engine and radiator changes the cooling lines for the trans were damaged?

Mine does that sometimes too.... but I just keep adding RADIATOR FLUID when needed...

well i know the fans are working cause when i stop the car, the fans run for a really long time. i can't tell if it's 1 fan or 2 but it runs.

cooling lines? maybe that's the problem. i know that there is no leaks.

i've done this. i even went as far as over filling it to the top just to see what would happen.

Has the water pump ever been changed?

after my second engine? nope. i'm actually doing the remedy water pump and thermostat today. i'm going to test it out. hopefully it will solve the problem.

I suspect that after all those radiator changes that there is no foam around the outside of the radiator to stop air bypassing it . Something to check anyway .

what do you mean by foam around the outside of the radiator? sorry, i'ma noob

There should foam pieces around the outside of the rad to stop air bypassing - I garauntee you don't have it after that many rad. changes .
This has proven to be very important in hot climates . A lot of guys put high performance radiators in and got worse cooling than stock .It was later discovered how important the foam is . You may need to look at a parts diagram to see where it is supposed to go .

it goes to both sides (left & right)

For some reason Mazda does NOT sell them as separate piece on the Rx-8, it comes with Stock Radiator as a whole,

for Rx-7 those foams have part number that you can order them directly from Mazda, just stick them on.

no biggie, I mean you can just go Home depot/Lowes kind of place and buy some Foam for heat pipes. same thing.

Thanks guys. I will check that out.

BTW Remedy Thermo and Water Pump did not do the trick, but I think it helped a little. I don't know....

Btw does anyone have a picture of the foam on the radiator?

you can buy a spray heat resistant foam or high temp silicone. Do it your self.

Also replace the themostat. Check the one oil cooler.

You can add another one if your mechanically inclined.

Turn the waterpump by hand and the fans. Just because they spin doesn't mean they are working correctly.

i replaced the water pump and thermostat on Friday with the remedy ones. Fans do spin cause I hear them in the garage after a long hot drive .

You've changed the radiator 3X, what about the hoses?

try using more coolant than water mix and some water wetter from redline