273 overheating

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redrag64

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I just bought a 64 Dart with paperwork documenting a complete engine rebuild about a year ago. Everything looks clean and legit. It lists a new 160 degree "heavy duty" thermostat. It runs fine while rolling, but wants to overheat at stop lights. Before I deal with the t-stat and other things, I have a question. It has an after market under-sized fan, and no shroud. Is there any way this is the issue, or do I need to do some real trouble shooting? Any adise would be gratly appreciated!
THANKS!
 
What is your timing at????
Get a 14-16" fan, and some kind of a shroud...The mopar viscous fan set up works good too.. Add a pusher fan??? Change the thermostat to 180*. It will actually run cooler.
All this is assuming the radiator is in good shape.

Bob
 
BobsDart said:
What is your timing at????
Get a 14-16" fan, and some kind of a shroud...The mopar viscous fan set up works good too.. Add a pusher fan??? Change the thermostat to 180*. It will actually run cooler.
All this is assuming the radiator is in good shape.

Bob
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Radiator is new as well - I'll give it a shot - thanks.
 
hi, I was wondering how a 180 deg thermostat makes a motor run cooler vs a 160 deg thermostat??
 
It slows the coolant flow and keeps it in the radiator longer.
 
The first motor i buillt was a 1967 273. It had issues with over heating.I finally took the original cast water pump off and found the impellar had broken apart in peices. The weird thing about the impellar was that it was made of some sort of plastic. I took the original pump to a shop and they rebuilt it with a steel impellar, it solved the over heating.
 
Additional info and question: Does anyone know what size radiator I should be using? The current radiator (which was replaced at the same time as the engine rebuild) only measures about 17" X 17" X 2" (mounts with a retro bracket that brings it in about 3.5"). Do I need to replace the fan, shroud, AND radiator, or should I start with the fan/shroud, and go from there.
THANKS.
 
perfacar said:
hi, in that case then a 210 thermostat should make it run colder??
Click to expand...
There is a limit. Most people that take the thermostat out thinking it will run cooler usually have overheating problems. The coolant doesn't stay in the radiator long enough to dissipate heat. You should have a shop do a pressure test on the system. A small leak can cause a pressure loss. Each pound of pressure raises the boiling point 3 degrees. (a 15 # cap raises the boiling point 45 degrees or from 212 degrees to 257 degrees. You may also have a blown head gasket or a cracked head or block that is putting hot combustion heat into the system. Does it actually overheat and boil out the overflow or is it just reading too high on the gauge? It may need a sender in that case. Mike
 
toolmanmike said:
There is a limit. Most people that take the thermostat out thinking it will run cooler usually have overheating problems. The coolant doesn't stay in the radiator long enough to dissipate heat. You should have a shop do a pressure test on the system. A small leak can cause a pressure loss. Each pound of pressure raises the boiling point 3 degrees. (a 15 # cap raises the boiling point 45 degrees or from 212 degrees to 257 degrees. You may also have a blown head gasket or a cracked head or block that is putting hot combustion heat into the system. Does it actually overheat and boil out the overflow or is it just reading too high on the gauge? It may need a sender in that case. Mike
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To be honest, I have only had the car a couple weeks. The first time I drove it around 10 miles, it over heated and came out of the overflow hose (no overflow basin) as I pulled into the driveway. I have done a few short drives (3 - 10 miles) sinse, and it has not boiled over. It seems to do fine when I'm going, but it starts to heat up (up around 210) at stop lights. Thanks for your time.
 
Remember the thermostat does not control maximum temperature.

The fact it only over heats when stopped shows it is a lack of air moving through the radiator. When you are driving around air is passing through the radiator and everything is fine.

You don't even need a fan when a car is traveling above about 30 mph.

Like I said above. Get a real fan. The fan alone may fix the problem.
 
Check to see that the fan was not installed backwards. This happened to me. After I figured out the problem, no more overheating, and I don't have a shroud.
 
1968FormulaS340 said:
Remember the thermostat does not control maximum temperature.

The fact it only over heats when stopped shows it is a lack of air moving through the radiator. When you are driving around air is passing through the radiator and everything is fine.

You don't even need a fan when a car is traveling above about 30 mph.

Like I said above. Get a real fan. The fan alone may fix the problem.
Click to expand...

The current flex fan is only a 13" fan. Do you think going back to the stock fan (17-ish") is good, or should I bump that up. Also, do you think the size of my new radiator has anything to do with it?
THANKS.
 
Also keep in mind you don't want the fan set far away from the radiator. On my truck the fan is set back BUT it has a shroud. Originally my '64 didn't really have shroud (more of a finger guard), but since the fan was close to the radiator it did fine. Right now I have a 17" fan properly spaced and no shroud on my 318 and even idling in 100 plus cali weather it has never gotten above 190.
 
toss the small fan and you should be good. As 68FormulaS said, overheating when sitting is normally an airflow issue... real fan = more air... keeping it close to the radiator is what you want. Shround helps even more but probably don't need it with the proper fan if it is close to the rad. I don't run a shroud on mine either, and no overheating issues. 360 in a 69 Barracuda.
 
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