placing a cover over the radiator before starting so that engine coolant can warm up

[TMcD_in_MI]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

OK, this may be a dumb question, but isn't it the engine thermostat's job to control how much coolant is allowed to flow through the radiator? If your engine is dead cold, the thermostat won't let any coolant into your cold radiator, right? So why would covering the radiator make any difference?

This is something I've never understood. It seems like if the thermostat is doing it's job, blocking the radiator is just not necessary.

Maybe someone can point out where my thinking has taken a wrong turn.

Tom

 

[Dusty]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

The reason that some people block part of the radiator (never block the entire surface) is that even though the thermostat is working, the air cools the liquid in the radiator enough that the thermostat keeps closing and opening and you can't keep enough heat in the engine for it to run properly. You have to think about the temperatures involved. The colder the incoming air, the harder it is for the engine to maintain temperature. By closing off part of the radiators surface you will minimize the amount of cold air that comes into contact with the radiator. Thermostatically controlled winter fronts are nothing new. They were routinely used on cars in the 1920's.
Dusty

 

[Doc_Bob]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

The reason that some people block part of the radiator (never block the entire surface) is that even though the thermostat is working, the air cools the liquid in the radiator enough that the thermostat keeps closing and opening and you can't keep enough heat in the engine for it to run properly. Dusty

I think it is even a bigger factor with diesel motors that run "cooler" or with less excess heat. In 10 degree weather, I think the motor would have a hard time producing enough excess heat unless runnig at full load.
Bob

 

[PineRidge]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

The reason that some people block part of the radiator (never block the entire surface) is that even though the thermostat is working, the air cools the liquid in the radiator enough that the thermostat keeps closing and opening and you can't keep enough heat in the engine for it to run properly. You have to think about the temperatures involved. The colder the incoming air, the harder it is for the engine to maintain temperature. By closing off part of the radiators surface you will minimize the amount of cold air that comes into contact with the radiator. Thermostatically controlled winter fronts are nothing new. They were routinely used on cars in the 1920's.
Dusty

Adding to what Dusty already said, most cars have either a clutch or a thermostatically controlled motor driving the fan to assist the engine with quicker warm-ups. The fan blade doesn't spin until the engine comes up to temperature. With most cuts the fan spins regardless of engine temperature and since most diesel radiators are made heavier than gas engine counterparts, the diesel engines take longer to reach normal operating temperatures in colder climates, hence the radiator covers.

 

[Doc_Bob]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

in colder climates, hence the radiator covers.

Mike, would cover the radiator or the grill/hood?
Bob

 

[Dusty]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

I'll bet that PineBridge would say that either will work, just do that which is easiest.

 

[MikeD74T]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

OK, this may be a dumb question, but isn't it the engine thermostat's job to control how much coolant is allowed to flow through the radiator? If your engine is dead cold, the thermostat won't let any coolant into your cold radiator, right? So why would covering the radiator make any difference?Tom

Tom, For the most part you're correct about the thermostat, except most have a small amount of bypass in case it fails closed, & to allow air to pass. An air bubble can insulate a thermostat from the water and cause it to remain closed when it should be opening. Besides cooling the radiator the air also cools the block directly. Without restricting the airflow somewhat block cooling can exceed the engine's ability to remain at or ever reach operating temperature. Many stationary engines have reversed fan blades (commonly known as winter blades) that blow from the engine to the radiator to prevent supercooling. That doesn't work well with moving vehicles. MikeD74T

 

[PineRidge]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

I'll bet that PineBridge would say that either will work, just do that which is easiest.

Actually I would say it's 6 of one or a half dozen of the other. (either, or)

And it isn't PineBridge there Dusty.....

 

[RalphVa]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

When we had a house in Vermont for skiing, I noticed a lot of cars and trucks with their radiators mostly blocked off in the winter. So, I did the same thing with my old Benz. You should only do this if you have a temperature gauge so you can monitor it.

Some (maybe most?) cars (and probably tractors?) have a small bypass around the coolant pumps, to keep the pump more happy when the thermostat blocks flow to the radiator (or from/to the engine, whatever). On some, the bypass is more than others. On our Toyota, it takes it about twice as long to warm up on cold mornings as either the Benz or the VW. Its bypass is probably bigger. Even though the thermostat has water flow blocked off back to the engine, the bypass keeps coolant going through the pump back to its suction. The length or amount of that bypass can cause some cooling in the early morning cold.

Ralph

 

[TMcD_in_MI]

Re: placing a cover over the radiator before starting so that engine coolant can warm up

MikeD74T -

Thanks for an excellent answer. I didn't know about the bypass and had thought that direct block cooling wouldn't be much of an issue. You clearly understand the situation and my question.

You too, Ralph!

Tom