Overheating 5.0

Rick Parker · #1 (**permalink**) 10-16-2001, 10:28 PM

Well it's part snake!!! I have a 91 5.0 5 speed Mustang GT in the family that has approx 65-70k on it in pretty good shape. Recently a problem has reared its head. It has a Ford Motorsport
aluminum radiator that has just been rodded out (only lower tubes needed any help) good compression, no oil being burned, and a new Edlebrock water pump. It overheats while idling with the a/c on. If you are in town traffic or stop and go for over 10 minutes it goes past 220 degrees. The perplexing thing is that once you are at speed normal temp is maintained. The fan clutch is fresh as is the fan itself. Any Ford techs out there? My sons pulling his hair out! Thanks

Rick

Dave Samson · #2 (**permalink**) 10-17-2001, 03:07 AM

Rick,
Sounds like when the radiator was reinstalled, you (or someone) installed the fan with the +ve and -ve reversed. This would mean that the fan is spinning in the wrong direction.
Hope I'm right, let me know.

dalola · #3 (**permalink**) 10-17-2001, 05:58 AM

Rick,
You may want to verify that temp. with something other than the factory gauge, if you haven't already. Those factory gauges, and sending units, are usually not very accurate.

If in fact things are as you say, the condition you describe sounds like either a capacity problem, or a fan problem. You say the fan clutch is "fresh", meaning new? Doesn't garantee a good part. Double check that. Try heating it up manually to make sure it locks. Also, is there a possibility you have an air pocket in the system? If you recently drained and filled the system, are you certain the correct amount went back in? Beyond this, not sure what else it could be in a basically stock vehicle. I've had many 5.0 Mustangs through the years, never experienced any overheating problems if everything was in order.
Good luck,
Dave

mustang man · #4 (**permalink**) 10-18-2001, 04:53 PM

I hate to bring up something as basic as checking the thermostat. It's easy enough to check to see if it is opening properly and if nothing else they are cheap to replace and yet somehow they often go bad.

aeroace · #5 (**permalink**) 10-21-2001, 05:32 PM

If the temp drops down to normal when the vehicle is moving, then it is an airflow problem. The fan's age has no bearing on its functional ability.How well does the shroud fit the radiator and fan combo? Don't think that more coolant in the ratio will help either. Water cools better than antifreeze. Is the water pump the correct rotation? They come in standard ratation(clockwise) and reverse rotation for serpentine setups.

Dave Samson · #6 (**permalink**) 10-21-2001, 07:55 PM

Could it be that a larger diameter pulley than the standard one is driving the water pump ?