Overheating Question???

[crimsonblack]

OK, I have installed a new 3 row aluminum radiator and new electric flex-a-lite fan set-up on my 87 5.0 vert. The mechanic told me I am moving so much more air that the car should be running cooler than it is. The transmission has been completely rebuilt and the temp is the same after the work was done as before.

The car still runs warm with the AC running. Outside temp about 115 to 120. Don't misunderstand, the car is running cooler, but not as cool as it should. I am planning to change to a 180 degree thermostat in the next few days.

My question for everyone is... What else is going to cause my car to run hot/warm? Could it be the coil or something to do with the transmission? All advice, experience and knowledge is welcome. Thanks for your help.

[NoSlo5.0]

The car is always going to run warmer with the ac on. The condenser is in front of the radiator. The air flowing into the radiator is hotter with the ac on, therefore the air out is hotter and the coolant is warmer. If your car has a 190F stat and the original cooling system could maintain the coolant temps near there, going to a higher capacity cooling system wouldn't necessarily mean cooler engine coolant temps would result. It's possible that you are maintaining the same coolant temps with more reserve cooling capacity on tap.

Do you have a decent shroud setup with the flex-a-lite setup? You may not be getting the airflow that think you should be otherwise.

[crimsonblack]

The car is always going to run warmer with the ac on. The condenser is in front of the radiator. The air flowing into the radiator is hotter with the ac on, therefore the air out is hotter and the coolant is warmer. If your car has a 190F stat and the original cooling system could maintain the coolant temps near there, going to a higher capacity cooling system wouldn't necessarily mean cooler engine coolant temps would result. It's possible that you are maintaining the same coolant temps with more reserve cooling capacity on tap.

Do you have a decent shroud setup with the flex-a-lite setup? You may not be getting the airflow that think you should be otherwise.

The flex-a-lite fan I purchased is for the Mustang 87-93. It covers the entire backside of the radiator.The airflow is so much better than the old style. You likely right and it's something I am stuck with. The fan has an adjustable thermostat and I'll make sure it's on the 180 degree setting than 240.

Thanks.

[NoSlo5.0]

It's pretty much a normal occurrence. You'd have to have one heckuva cooling system to be able to remove the same amount of heat from the coolant when the ac is on. I'd say so long as you're still able to control the temperature in stop and go traffic then no worries. My system is just marginal in 100F heat and the ac on. It won't overheat, but it's running hot enough that the EEC is pulling a bunch of timing.

[crimsonblack]

Thanks. It sucks at 115 and higher. I managed to get around in the heat today for two hours of traffic before she started to redline, and that was with the AC at the halfway point. I was impressed.

It is weird how the temp gauge moves up then drops quite a bit. This goes on all day. I am going to go ahead and do the thermostat next week. It's never been changed since I purchased the car a year ago. I'll try a 180 degree thermo and check the system out. Flex-A-Lite has a newer Mustang fan that uses an "S" type style fan blade and reportedly moves 35% more air than the unit I bought last week. There was just a three wait time to get the fan and this is my week off. Wanted something done now. The new fan is about the same as the one I have and will likely attempt the change next summer.

Thanks for everyones help.

[babeslx]

This is probably not the case with your ride but after I pulled the 2.3 and had the 5-0 dropped in my 87 LX the temp would run up to the top and drop - puking lots of green into my overflow. Turns out the thermostat was in upside down! Now the new one's in properly it runs dead centre. Of course, it rarely gets over 25C here and I don't have any AC.

[hrsepwrbrat]

It is weird how the temp gauge moves up then drops quite a bit. This goes on all day.

The temp gauge moving up and down like that is normal. When it goes down, that tells you that your thermostat is working. It means it opened up and let the warm coolant flow to the radiator to cool off, and the cool stuff in the radiator to circulate and cool the motor. That changes the temp, so the gauge will show that change. The lower degree thermostat you get, the more often it will open up, which will cool the motor more often, but leaves less time for the radiator to cool the coolant. Anyway, there's my 2 cents...