Thermostat Temps

[51_Meadowbrook]

I was looking in the book for my ‘51 Meadowbrook and it was saying that they recommend a 160 thermostat. Why would they want a 160 vs a 180? Wouldn’t the higher block temp burn the fuel better, not to mention the higher interior heater temp? Is there a danger to using a thermostat not rated to the recommended temperature?

[plymouthcranbrook]

160's were often used in the summer when the cars were new. Was not unusual to change the thermostat twice a year so it would run cooler in summer and warmer in winter.  Gas mileage was not that big a deal as now.,  I have a 180 in my 52 and run it all summer with no problems.

Edited May 9, 2019 by plymouthcranbrook

[thisoldtruck]

The following came from a Chrysler technical reference manual and is, I believe, the answer to the OP question:

 

THE COOLING SYSTEM

One of the complaints most frequently heard during cold-weather operation is in relation to the engine cooling system and the performance of the car heater. Therefore, a review of some of the fundamentals of the cooling system may prove helpful.

Heat developed within the engine is converted to mechanical energy to operate the engine. Not all of the heat is used for that purpose, however. Some heat is given off through radiation, and some is carried away by the exhaust system. The balance of the heat not used to operate the engine is carried away by the cooling system. In other words, the cooling system is carefully designed to control the operating temperature of the engine for its most efficient performance, and to carry away the excess heat.

If the engine runs too cool, the fuel mixture won't burn completely. Some of it will find its way down the cylinder walls and into the crankcase where it dilutes the oil and helps to form acid. If the engine cooling system is not adequate to carry away the excess heat, the engine will run too hot. The coolant will boil, and engine damage may occur.

 

THERMOSTAT

The thermostat has a very important job to do. It must stay closed when the engine coolant is cold, permitting circulation of the coolant within the engine and thus provide a short warm-up period. Then, when the coolant has reached operating temperature, the thermostat must open and permit coolant circulation through the radiator. Starting with the 1960 models, all engines have a 180-degree thermostat as standard equipment. This means a permanent-type antifreeze must be used in the cooling system. If an owner wanted to use an alcohol-base antifreeze he would have to install a 160-degree thermostat.

Some technicians believe that different thermostats should be used for summer and winter operation, on the theory that overheating is less apt to occur in hot weather with a 160 degree thermostat.

This is not true. Engine cooling is just as effective with a 180-degree thermostat as with one which opens at 160 degrees. Therefore, changing thermostats twice a year is an unnecessary inconvenience and expense.

If abnormal conditions are encountered, and the coolant temperature rises above 180 degrees, the thermostat will be fully open regardless of whether it is a 160-degree or a 180-degree thermostat. This means the maximum cooling will take place with either thermostat, and the possibility of overheating is no greater with on than with the other."

 

[51_Meadowbrook]

Thank you to both of you. Unlike a lot of people I like to drive my car even when it’s cold or raining so I need to have heat and a defroster. With the 160 it never seems to warm enough and it takes forever to defrost the windshield. 

[plymouthcranbrook]

16 hours ago, 51_Meadowbrook said:

Thank you to both of you. Unlike a lot of people I like to drive my car even when it’s cold or raining so I need to have heat and a defroster. With the 160 it never seems to warm enough and it takes forever to defrost the windshield. 

Something to remember about the defroster in an old Mopar is that it just recirculates the air in the cabin, not a separate feed as in modern cars. So eliminating moisture is harder than you might  expect.

[greg g]

I have experience with the model 36 heater in my p15.  There is no provision to provide the system with fresh air so it merely recirculates the humid warm air back on the inside of the windshield. If you open the cowl vent a bit it helps but if it cold and rainy and you have two or three people in the car with damp clothes and wet shoes it's a pretty hopless deal. Even keeping a towel to while off the moisture only works for a time or three the it adds to the dampness already in the car.  Itsvlike those bozos you see in the winter with their windows all fogged up with the heater and fan on full blast wondering why they can't clear the windows.  Deselect recirculate on your climate control.

[Adam H P15 D30]

Modern cars use the air conditioning to dry the air in defrost mode.  Without AC, your blowing either outside humid air or inside humid air on the windshield.  I also drive my 49 a lot including rainy days so like Greg says, keep a rag handy to wipe the windshield.

FWIW, my heater works very well and very warm with a 160 thermostat, engine runs at 170, electric fan kicks on at 185 and off at 170 so hot days it sits around 180.

 

Adam