Cool/Heat: Engine running cool?

[1961lark]

I have a 1961 Lark with a 259, and when I'm driving on the highway, (anywhere from 55-65 mph) the engine is really cool. It will warm up fine and stay in the middle of the gauge when I'm tooling around town or idling, but once I hit the highway it seems to drop down to the bottom of the C on the gauge. It almost goes all the way back down to cold.
When I run the heater it blows out nice, warm air, so the coolant can't be too cold can it? how do I check the accuracy of my gauge and or sender? Or is my thermostat getting stuck open possibly?
Should I even worry about this? I read that almost everybody has had problems with overheating their stude' at one time or another. It runs and drives like a champ (well, a Lark) the needle just doesn't get very high on the gauge. The choke opens fully and properly. what should I do?

[junior]

could be a sticking t-stat. pull over to the side of the road when the car is running cold and feel (or measure with a I-red thermometer) the temp of the upper rad hose. do the same thing in town when the car is running normal temp. large difference in temp of the hose?....I'd be changing the t-stat. junior

[Bud]

More likely than not, you have a defective thermostat. Thermostats are inexpensive so I would recommend replacing it. My personal preference in Studebaker engines is a 180 degree thermostat. Bud

[1961lark]

All right, I'll be sure to check it when it's running cool and when it's not. I notice that there are three different temperatures for studes. 160, 180, and 195. Is there any benefit of running one or the other?

[RDWEAVER]

Probably the T-stat. Probably stuck open. The heater gets the water supply from a radiator by-pass so to speak so it will always be warm compared to the radiator. The engine will not operate efficiently unless it is properly warmed up. T-stat's are cheap I use a 180 degree here in Iowa.

[DWBookout]

Motor car thermostats are designed to fail in the open position, usually because the bellows looses pressure. No reason to believe this would not be the same case with our older cars, given the basic technology has not changed all that much. Cars with electric fans or viscous couplings let the fan freewheel or not operate at all when the movement of the car is supplying adequate air flow to the condenser. So, the first and cheapest place to go is mostly likely the thermostat.

[Mike Van Veghten]

DWBookout -

No, actually the standard thermostat will close if it fails.
You CAN get them that when they fail, they open, but they are about twice the cost and not all standard parts stores offer them.

Mike

[junior]

Depends how you define failed or stuck...no matter lots of thermostats fail or get stuck in the great white north...you and your engine stay fairly warm on moderately warm days, but on cold days when you get out on the highway you freeze...rap the thermostat housing with tool at hand such as a lug wrench and you are treated to heat in the interior again...BTDT more than once. cheers, junior

[southbend]

To 1961lark: Thanks for asking this question. I have a similar situation with the '35 Dictator I acquired late last Fall. Figured it was a wonky thermostat. Now I'm convinced. Anytime you flush the radiator, I think it's a good idea to change out the thermostat(s). Very cheap insurance.

[Bud]

I've had thermostats stick closed, stick completely open or partially open so I don't believe there is any set pattern as to how they fail. Bud

[Gunslinger]

You can buy thermostats designed to fail in the open position...known as "fail-safe" thermostats. These will keep the car from overheating and possibly suffering damage.

They cost more and I think they're worth it.