Overheating Problems -Almost Ready to Give Up

[Snowdoggie]

does it overheat when stopped or moving?

When moving.

[Snowdoggie]

I replaced the water pump.
I replaced the head.
I replaced the upper radiator hose.
Twice.
The second time with an $60 silicon radiator hose from Moss Motors.
I replaced one of the heater hoses.
Nothing is leaking.
I replaced the thermostat.
I replaced the heat sensor on top of the thermostat.
Both fans are running.
I changed the wiring so that both fans are running at the same time all the time, bypassing the relay that turns one of the fans on when the thermostat hits a certain temperature.

Just now I drained the radiator again. Changed the antifreeze with the Prestone 50/50 mixture. Added one half bottle of Water Wetter.

Drove it around the neighborhood for about 20 minutes. It overheated again.

What's left?

[Sharpie]

Drain some out and add water. 50/50 not great for Texas.

[Walsted]

I replaced the water pump.
I replaced the head.
I replaced the upper radiator hose.
Twice.
The second time with an $60 silicon radiator hose from Moss Motors.
I replaced one of the heater hoses.
Nothing is leaking.
I replaced the thermostat.
I replaced the heat sensor on top of the thermostat.
Both fans are running.
I changed the wiring so that both fans are running at the same time all the time, bypassing the relay that turns one of the fans on when the thermostat hits a certain temperature.

Just now I drained the radiator again. Changed the antifreeze with the Prestone 50/50 mixture. Added one half bottle of Water Wetter.

Drove it around the neighborhood for about 20 minutes. It overheated again.

What's left?

Compression check to ensure that there isn't a head/headgasket problem. ( I see you replaced it, but that could still be the problem)

Fans are blowing in the correct direction, right? How does the inside of the radiator look?

[Rogue]

Highly unlikely, but I worked on a miata that overheated over 65 mph.
After chasing it like you did, turned out to be timing belt off one tooth.
Ran like a champ but progressively got hotter over 65.

My current Miata doesn't like dirty air.
If I close it up behind slower traffic it warms up. (Not to overheating)
Move over to clean air, back to normal.
It hates semi's (sorry Paul)

[POS Racing]

What's left?

The radiator.

[SirHustlerEsq]

make sure the t-state is opening all the way, you certainly have the tray behind the radiator, and maybe you want to try running it with just straight water to see if anything changes. 110* heat is hard on any car though.

[MadMonkey]

I know that my NA tends to overheat when I have my Wabbit teeth in the grill (summertime)... it likes a lot of airflow.

[channelmaniac]

The radiator.

And the heater core. The coolant goes from the back of the head where the temp sensors are through the heater core and out to the back of the water pump to go to the radiator.

The temp sensors are on the back of the head next to the firewall and there are 2. One is for the temp gauge on the dash and the other is for the ECU to monitor engine coolant temps.

The thing you replaced on top of the thermostat is the switch to turn the fans on, it's not the temp sensor.

You can check if it's the heater core that's blocking the coolant flow by putting a U shaped hose in place of the 2 that go to the firewall. That will effectively bypass the heater core.

[SirHustlerEsq]

And the heater core. The coolant goes from the back of the head where the temp sensors are through the heater core and out to the back of the water pump to go to the radiator.

The temp sensors are on the back of the head next to the firewall and there are 2. One is for the temp gauge on the dash and the other is for the ECU to monitor engine coolant temps.

The thing you replaced on top of the thermostat is the switch to turn the fans on, it's not the temp sensor.

You can check if it's the heater core that's blocking the coolant flow by putting a U shaped hose in place of the 2 that go to the firewall. That will effectively bypass the heater core.

these is some debate over that because the heater returns hot water back to the mixing manifold, then into the motor. Some turbo cars run cooler with a valve in the heater return, if they have not changed water routing.


Mazda really screwed us with crappy cooling on these cars:
tiny mouth / heat exchanger opening
water goes out the wrong side of the head
hot water from the heater recirculates with cold water
radiator could be bigger

[Snowdoggie]

Would it be worth it to get one of those $500 aluminum radiators?

[SirHustlerEsq]

Would it be worth it to get one of those $500 aluminum radiators?

no, the car should cool with the stock radiator. Check everything else first...if everything checks out, then replace the radiator with something better than stock. Hit up Gary for a koyo.

[sammm]

Would it be worth it to get one of those $500 aluminum radiators?

How about a new $150 OEM radiator?

[altiain]

How about a new $150 OEM radiator?

+1. Unless you spend a lot of time on the track in mid-summer, a $150 OEM replacement radiator will do you just fine.

[Miatamaniac92]

Slightly more than $150:
http://www.miataturbo.net/forum/showthread.php?t=24517



"To do this group buy, I need 5 people. MSRP on the radiator is $320. MAP (Minimum Advertised Pricing) is $240. If I can get 5 people to commit, I can offer the radiators at an additional 10% off, making the price $216.

Additionally, if I can get 10 people, I will do free ground shipping for everyone."

Chris

[Radio-Active]

This place offers free shipping at a resonable price for anything over $50. Go for the two row radiator.
Linkie 1:
This is a local place off of Regal Row and Irving Blvd that has a TYC sign on the building. Unfortunately, they do not have the two row radiator listed.
Linkie 2: