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Have had ongoing high engine temperatures with my 69, 428. It operates in the normal range as long as it is moving. As soon as it gets into traffic the temp goes way up. Once the heat gets into the cast iron intake, it affects the carb & it stalls at low speed going over things like speed bumps. I have added Water Wetter from Redline and that helped a bit. Also installed a Derale electric fan but don't like it as it doesn't belong on a 69. Also because we have a mild climate here I diluted the antifreeze with de-ionized water. It doesn't boil over any more but still overheats in a traffic jam on a hot day. Is this normal with 428's and if not, what other options are there to reduce operating temperature? Thanks
John
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As a longshot, If the thermostat is missing or stuck in an open position the water can circulate too fast and not cool down enough in the radiator and also cause overheating. Untill you find a fix remember if it starts overheating turn the heater on to hot and the fan on high to help cool the coolant, of course your going to get hot inside the car!
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(06-29-2011, 02:17 AM)Rare Pony Wrote: As a longshot, If the thermostat is missing or stuck in an open position the water can circulate too fast and not cool down enough in the radiator and also cause overheating. Untill you find a fix remember if it starts overheating turn the heater on to hot and the fan on high to help cool the coolant, of course your going to get hot inside the car!
+1 starting with the thermostat is going to be your least expensive option, make sure the hoses are firm. After that then its going to come down to Hoses, water Pump, or the radiator may need some servicing depending on its age.
Not that the below is for you, but I try to leave info with a topic that someone less experienced might need in the future.
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Thanks for the idea. For the cost of a thermostat & a gasket it is worth a try. The rad is a 4 core and appears to be clean but a flush probably wouldn't hurt. Interested in hearing from 69/70 owners with original cast iron intakes if running hot in traffic is a common experience?
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Is the fan shroud still in place? If not, in traffic is where you'd notice.
I think it would be a good idea to pull the radiator and take it to a good shop. They can hot tank it and, if necessary, do a "rod out". You simply can't recreate this at home with a flush kit. If you take the radiator to the shop yourself, it's really not very expensive to have it serviced.
Old Mustang cooling systems get clogged. It's normal. Everything can look clean, but the coolant passages in the radiator are blocked.
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The fan shroud is in place but it has been 15 years since the radiator has been serviced so I will add this to the list.
Thanks
John
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