overheating BGT with A/C
afdave
07-16-2006, 06:07 PM
Good folks,
Recently added A/C and Alt. to my 67 BGT Special Edition.
Problems I have are running hot (over 212ºº at speed 60mph)), I have installed an electric fan with the stock 6 blade metal fan, timing not advanced, 160º thermostat, have condensor in front of radiator as well as oil cooler. After a run you can't touch anything under the hood.
What do I do at this point. Oh yes, the A/C works like a charm. It's a setup from Tampa Nostalgic Air, a system that Moss wil be selling.
dave
Recently added A/C and Alt. to my 67 BGT Special Edition.
Problems I have are running hot (over 212ºº at speed 60mph)), I have installed an electric fan with the stock 6 blade metal fan, timing not advanced, 160º thermostat, have condensor in front of radiator as well as oil cooler. After a run you can't touch anything under the hood.
What do I do at this point. Oh yes, the A/C works like a charm. It's a setup from Tampa Nostalgic Air, a system that Moss wil be selling.
dave
KimMG
07-17-2006, 05:26 AM
You should use a 180 to 195 thermostat. 160 will not close and allow the coolant to cool off in the radiator. Your motor will run more effeciently between 180 and 195.
Check your coolant level
Check your hoses to make sure they are not collapsing.
Restricted air flow. Make sure the fins are clean of debri and aren't bent on the radiator, a/c condenser, and oil cooler.
How old is your water pump? After many years of use the vanes will wear out and not circulate enough coolant.
Is the radiator clogged. Start your car and let it idle up to operating temp, turn off motor and feel the radiator for cold spots. Cold spots are indicative of a clogged/restricted radiator.
Radiator capacity. Maybe you need a four row one due to the extra load.
Head gasket and/or a cracked head. Check the oil for level and coolant contamination. Heads usually crack or the head gasket weeps between the #2 and #3 spark plugs.
Is your car properly tuned. Too far advanced timing will cause a motor to run a little warmer than it should.
Does your new fan pull or push fresh air into the engine compartment? Do you have some kind of shroud around the fan to help in directing air flow? At what temperature is the fan set to come on?
Check your coolant level
Check your hoses to make sure they are not collapsing.
Restricted air flow. Make sure the fins are clean of debri and aren't bent on the radiator, a/c condenser, and oil cooler.
How old is your water pump? After many years of use the vanes will wear out and not circulate enough coolant.
Is the radiator clogged. Start your car and let it idle up to operating temp, turn off motor and feel the radiator for cold spots. Cold spots are indicative of a clogged/restricted radiator.
Radiator capacity. Maybe you need a four row one due to the extra load.
Head gasket and/or a cracked head. Check the oil for level and coolant contamination. Heads usually crack or the head gasket weeps between the #2 and #3 spark plugs.
Is your car properly tuned. Too far advanced timing will cause a motor to run a little warmer than it should.
Does your new fan pull or push fresh air into the engine compartment? Do you have some kind of shroud around the fan to help in directing air flow? At what temperature is the fan set to come on?
Flash75
07-17-2006, 03:14 PM
In your case running a 180 or 195 thermostat will not help your high speed cooling. The thermostat prevents engine temperature from going below the temperature rating of the thermostat. The 160 stat does cause the engine warm up slower but once it passes 180-195 it doesn't matter as those thermostats will not cause the engine run cooler. I assume Tampa Nostalgic Air installed the electric fan and a controller so the fan is on any time the ac is on. That is standard for cars with ac. Usually a puller fan is more efficient than a pusher fan, but either way the ac condenser is adding additional heat that passes through the radiator. If the radiator or cooling system is marginal in it's normal configuration adding the load of an ac will probably cause it to overheat.
Is your car overheating or just running hotter than you like? Is the radiator boiling over when the engine runs hot? You didn't mention if it runs hot in slow or stop and go traffic? How is the temperature with ac off? Technically it isn't overheating if it doesn't boil out the coolant. If the radiator hasn't recently been tested and cleaned I would remove it and have it flow tested and cleaned.
I realize you have to run some antifreeze with ac but a lower concentration of 20%-25% provides better heat transfer than a 50/50 mix. Some people have used Red Line water wetter with some success. I used it in a Jensen Interceptor and didn't notice any improvement.
If everything is in order here are some steps that may help. If using a 7 psi radiator cap try a 10 or 13. The higher pressure will raise the boiling point of your coolant but will not lower the running temperature. Be sure your hoses are all good before using a higher pressure cap. Consider using dual electric fans. Recently I have seen some air conditioned MGB's with dual electric fans and no engine fan. The ones I have seen were pushers and had the ac condenser close to the radiator as in modern cars with ac. The fans are built into a shroud and extend past the ends of the radiator. Your fans should cover as much of the radiator surface as possible. Having the exhaust manifold and down pipes coated internally and externally by Jet Hot or similar coatings will remove some heat from the engine compartment.
http://www.jet-hot.com/pages/headercoatings.html
You will have more heat in the engine compartment than a car without ac has because the engine has a bigger work load. Good luck, hope you get it worked out, turning on the heater to cool a hot engine isn't fun.
Clifton
Is your car overheating or just running hotter than you like? Is the radiator boiling over when the engine runs hot? You didn't mention if it runs hot in slow or stop and go traffic? How is the temperature with ac off? Technically it isn't overheating if it doesn't boil out the coolant. If the radiator hasn't recently been tested and cleaned I would remove it and have it flow tested and cleaned.
I realize you have to run some antifreeze with ac but a lower concentration of 20%-25% provides better heat transfer than a 50/50 mix. Some people have used Red Line water wetter with some success. I used it in a Jensen Interceptor and didn't notice any improvement.
If everything is in order here are some steps that may help. If using a 7 psi radiator cap try a 10 or 13. The higher pressure will raise the boiling point of your coolant but will not lower the running temperature. Be sure your hoses are all good before using a higher pressure cap. Consider using dual electric fans. Recently I have seen some air conditioned MGB's with dual electric fans and no engine fan. The ones I have seen were pushers and had the ac condenser close to the radiator as in modern cars with ac. The fans are built into a shroud and extend past the ends of the radiator. Your fans should cover as much of the radiator surface as possible. Having the exhaust manifold and down pipes coated internally and externally by Jet Hot or similar coatings will remove some heat from the engine compartment.
http://www.jet-hot.com/pages/headercoatings.html
You will have more heat in the engine compartment than a car without ac has because the engine has a bigger work load. Good luck, hope you get it worked out, turning on the heater to cool a hot engine isn't fun.
Clifton
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