My daily driver 1990 LX Fox runs a little hot. The temp gauge often reads at just above the O letter in NORMAL. This fluxuates between driving and in idle like at a stoplight. While driving the needle falls down to R M but sometimes hovers around O as well. It has always done this. The previous owner mind you put in a 140mph speedo and it always tells me that I have "low coolant" but I check the radiator & its full so I don't know if its that. Another thing is that it has an aftermarket radiator & fan but the engine is stock w/ an AOD. Any suggestions?
I've heard that w/ under drive pulleys makes it run warmer.

 

The stock gauge is highly inaccurate. to really know what is going on you need real temps, O, A, etc really means nothing. I would either install an aftermarket gauge temporarily if you don't want an aftermarket gauge or what ever you want ( they are real simple to install). The EFI stangs run 210* +/- 5 normal operating temp, running them to cool screws with the computer. In traffic they can get up to 215* and then drop when moving. I autometer gauges and she runs a perfect 210* or just under on the hottest days .

A few things... Aero foxes are under the bumper breathers, the air deflecter mounted on the core support is huge to the cooling of teh aero fox since it directs air up to the radiator. Make sure you have a fan shroud, this directs air across the radiator surface and aid in reducing under hood temps, if it is an electric fan make sure it produces enough cfms and covers enough of the radiator. yes underdrives tend to run the car slighly warmer but shouldn't be an issue. If you have A/C even if it doesn't work make sure leaves and other crap isn't between the condensor and radiator, this blocks air flow.

 

Just like Skunk says He brings up some good points. But the factory gauges tend to suck. But things you can check is the Thermostate. I would get a new one 180* and gasket. If your set on keeping the factory gague Try replacing the sending unit. Which is on the lower intake. If I remember right it's on the drivers side by the front of the intake.

 

usually on the fox when the temp sendor is bad it pins full hot or doesn't read. The trouble with the stock gauge is "O" or "A" could be fine, this why real numbers are needed. he could be running totally normal but the way the lame stocker reads is throwing him off.

this is my current setup,

 

Thats a clean look, in my 90 fox i had the pod gauges on the driver side panel, it to was a real nice dress up

 

Like others have stated, definitely get an aftermarket temp gauge as the stockers are just dummy gauges. If you don't want to completely block your middle vents like skunk21, autometer should still sell a 2 pod panel with vent slots for air to pass by. I recommend an oil pressure gauge to go along with the water temp gauge if you go this route.

As for the speedo your car came stock with a 140. The low coolant light sensor, if I'm not mistaken, should be in your coolant overflow tank. If it's still there it's located against the radiator on the driver's side of the shroud. Check the tank, sometimes they leak, or at least I had problems with mine in my 88'. If it's empty I would fill it up to the proper line and that should turn off the light.

Also the under drives could make it run hotter depending on what setup you have. On both my old 88 & 89 foxes I ran a very small under drive crank pulley with an over driven water pump pulley and had no issues. I can't really help you there other than personal experience.

If you get an aftermarket gauge and it's still running hot. Which to me I didn't like to see over 200 running a 180 thermostat, but this is just personal preference so others may disagree. Then I would start with a new 180 thermostat & fluid flush, using a 50/50 coolant/distilled water mix with purple ice coolant additive.

From what I've been told since I got into working on foxbodies with my father. Usually cooling problems at a standstill is a fan issue, over heating while moving is a problem with the cooling system. That's usually how I go about finding a cooling problem at least.

Hope this helps,
Bill

 

 

Also . This is where I start. It isn't always gospel but always a good starting point. But I will add that standstill and slow driving speeds would be fan control and highway or faster cruising would be radiator more in control. very good though.

 

Thanks for the all the replies. I doesnt seem to be an outstanding issue thankfully. With the holiday weekend I'm going to tinker around and go over the suggested pointers.