1990 Mazda Miata temperature gauge in the hot zone!

Maintenance/Repairs
1

I have a 1990 Mazda Miata. My temp gauge goes up(very close to the h level) when I turn on my ac or fan, especially
during hot days. I had my radiator flushed a couple of months ago and just had the temperature gauge and sensor replaced.
My mechanic said both fans are working and he can’t seem to figure out what the problem is. Any suggestions would
be greatly appreciated.

new update, radiator replaced and radiator cap and the temp gauge is still creeping up to the hot zone. What else is there?

thanks,

Terry

2

I think I’d replace the radiator cap first. It’s not expensive, you can do it yourself, the total cost will be far less than a visit to your mechanic. You kind of have the classic symptoms of a bad cap, especially if you notice the temp rising when going above 60 mph and/or going up hill.

3

I agree with starting with the radiator cap. But your car is old enough that you could possibly have a crudded up radiator - even a flush can’t fix that. Does it seem to get hotter when you are sitting at a stop light? Or is it hot when it is running on the highway?

4

A flush can’t get rid of some of the more serious crud, but a flow test will tell you if it’s working correctly or not. After 21 years, it’s most likely tired and in need of replacement. That’s a long time for something that gets hit by every bit of debris you’re driving through.

5

Repair and Maintenance 1990 Mazda Miata temperature gauge in the hot zone!
tebbyr July 31 EditReport
I have a 1990 Mazda Miata. My temp gauge goes up(very close to the h level) when I turn on my ac or fan, especially
during hot days. I had my radiator flushed a couple of months ago and just had the temperature gauge and sensor replaced.
My mechanic said both fans are working and he can’t seem to figure out what the problem is. Any suggestions would
be greatly appreciated.

new update, radiator replaced and radiator cap and the temp gauge is still creeping up to the hot zone. What else is there?

thanks,

Terry

6

I just posted a while back on a temp gauge hot zone problem on my 1990 Mazda Miata. thanks for all of your suggestions but I’ve done everything that was mentioned and I still have a problem with my temp gauge going up into the hot zone after driving 20-30 minutes either in hot weather or cool weather. Here are the repairs with no results.
temp gauge replaced, sensor replaced, radiator replaced and radiator cap. what else is there?
Any suggestions would be greatly appreciated.

7

Tried replacing the thermostat yet?

8

Have you checked to see if the water pump is leaking? Are you losing coolant?

9

Warm up the car. Check for one hose to be very hot, the other to be cool. Carefully remove the cap and look for coolant flow in the radiator, especially when you rev the engine. If you are not getting flow, then you need to trouble shoot that problem. It could be a hose that is delaminated on the inside, a stuck thermostat or a water pump with a broken impeller.

If your water pump is driven by the backside of your timing belt, the belt could be slipping because the water pump is starting to freeze up. If that is the case, you will need to replace both the belt and pump.

If the water pump is driven by the serpentine belt, check that it is not slipping.

10

When you drive, is your car producing white smoke from the tailpipe? Are you losing coolant? If so, it could be a head gasket…