v8 slow to warm up in cold weather

[EMG7895]

A little background: 99 v8 with new water pump, radiator, hoses, thermostat, etc. in August. Warms up normally when the ambient temp is above ~45°F. When the temp drops below freezing it takes a very long time for the temperature to even reach the bottom of the scale. When driving at highway speeds for over an hour the temp still does not reach the middle of the gage. Could this be a bad thermostat?

 

[bobflood]

Is it just the gauge reading that is a concern, or are you freezing to death also? If your heater is normal, first thing to check is the temp sender unit for the gauge. If the gauge is right and the engine really is not warming up, then either thermostat or fan clutch (in that order). Either could prevent the engine from getting up to normal operating temp.

 

[EMG7895]

When ambient temp is warm gage acts completely normal, when cold gage does not show it warming up and heat gets warm but not hot like it should. Because of this I believe the sensor is fine.

 

[bigcrunch]

put a piece of cardboard in front of the radiator that covers about less than half of the area and see what it does.

 

[CDW6212R]

Ditto what has been said. Thermostats are high failure rate parts, often they don't open when they should etc. Even when new, be suspicious of them until you know they work right.

The fan clutch is also a good thought because if they drag(run full time), that will keep the coolant cold and not get much heat in the engine.

My 99 with SOHC V6 and an electric fan will not make the fan run unless the truck sets still for a while. Normal driving keeps the engine cool to the point of the T-stat rating. So in cold weather I hardly see more than 180 driving. If the T-stat sticks open then you'd see temps well under 100.

These trucks have extremely efficient radiators.

 

[Spdrcer34]

Cardboard infront of the radiator.....you don't say where you live, but if it get below 20 regularly, AND you drive faster than 45mph for extended time periods during your commute, I would block about 1/2 of the radiator with cardboard.....just make sure your attaching it with something that is easily (read: FAST) undone, when the weather warms up, like zip-ties.

Ryan

 

[SoNic67]

I did push up the cardboard pice on the radiator itself, with no zip ties. Has nowhere to go.
The trick is to push it upwards from beneath the bumper and then rest it on the pice of plastic that is covering the bottom of radiator. It's too cold out now for pics

 

[CDW6212R]

This is simpler, take a piece of cardboard sized to fit down in front of the radiator, from the top. I made one two years ago when my T-stat failed open. It was about a foot tall and 18" wide. Bend the top edge to make about a 1-2" lip. Fold it hard there and put it down in front of the radiator. The lip will keep it from falling down, and it will stay there until you open the hood and remove it. Nothing is needed to hold it there with the hood shut.

 

[EMG7895]

I'm going to try a new t-stat first and go from there. Just for fun, anyone know if the x-cal 2 can datalog coolant temps?

 

[OneLever]

If you put a piece of cardboard in front of the radiator. Do it on the side that does not have the external transmission cooler. On a second gen V8 this would be the left (driver's) side. You'll be able to see it.