RXTHIS

ok when i drive my car normally. like either shift at 3000 rpm or just dont stomp on it my temp gauge stays at half.. but when i start to push my car 7000 shifts and high speeds it starts to go up. what would be causing this. i thought the thermostat. how hard is it to change and should i cange it anyways.. thanks
dave

bl|nk

thermastat is easy to change I believe upper radiator line. 3 bolts where it meets the block and that's about it. I'ld do a coolant flush while you're working on it since that could be a source to your cooling issues if that hasn't been changed in a while. Is your overflow canister atleast at the low line? does your car seem to be eating any oil? I just got done searching on this and their is a lot of good info on coolant leaks and just coolant in general

RXTHIS

yeah its starting to use a bit more oil.i think i will change my coolant change with a nice flush cause its getting colder anywasy and the theromastat any other ideas...thanks

DriftinJim

iTrader: (24)

Revving the car will cause the temps to go up. As long as it stays within the normal operating range, you are fine. You could have an air bubble in the cooling system or be low on coolant.

GatorRX

Yes, change the t-stat. Absolutely get the factory one from your Mazda dealer. One word of advice - spray penetrant oil on the t-stat housing nuts for a day or two before you change it, the studs have a bad habit of getting rusty and breaking on high-mileage cars. This sucks if it happens.

If the t-stat doesn't do it, start looking to buy a new radiator, yours is probably plugged up...

Aaron Cake

iTrader: (1)

Continuous high RPM operation will cause the water pump to cavitate. You can fix this by installing a set of underdrive pullies. Of course, all cars will run hotter when pushed...

It's not a thermostat problem.

GatorRX

Running up to 7000 rpm occassionally in a street car isn't going to cause cavitation. That's just BS Racing Beat uses to sell $65 pulleys. If you are running a road race motor at 8-9000 rpm constantly, you could see a cavitation problem, but that's not what's happening here.

If his motor was abused, the impeller on the water pump could have rusted out, but that's not likely.

My money is on the T-stat. I've seen this on 7's more times than I care to think about (including a car just two weeks ago doing the EXACT SAME THING!). Change the T-stat first, it is the cheapest and most likely cause of your problem. If it sticks partially open, it is going to impede the coolant flow in the motor, and it will cool OK when its being driven easily, and overheat when driven hard or on the highway.

autocrash

If it is stuck partially open, you'll be able to feel the coolant running through the hose before the engine comes up to operating temp... maybe you should check that?

RXTHIS

thanks for all the advice. i am gonna check tomorrow... where do i get the underdrive pulleys in toronto

RX7BEAR

the water pump housing on my 87 GXL looked like the moons surface when I was changing my pump were it is suppose to be machined !!!!! That was the reason mine kept running very high temps.