my temperature gauge moves a lot. sometimes it goes into the red and the car shuts down. the water pump was replaced six months ago and the thermostat was replaced last week. the heat comes and goes but not in sync with the temperature gauge. sometimes the gauge will stay steady for the entire drive. there is no loss of antifreeze and no leaks.
What year Chevrolet Venture and how many miles?
IS the engine actually overheating? How do you know that it is? There can be other causes of the erratic temperature gauge indication and the engine shutting off; such as, an electrical problem.
There is no steam coming from the engine compartment and no loss of fluid. The gauge only goes to hot for a few seconds and then returns to normal. The car doesn’t shut off completely, it just looses power for a few seconds like it isn’t running on all cylinders then it is fine once the gauge gets out of the red. I can’t get stopped quick enough to get out and pop the hood before it goes back to normal.
The problem could be an air pocket trapped in the cooling system. If there is, when the air gets to the heater core they’ll be no heat from the vent system. If this pocket of air gets to the water pump the coolant flow stalls. This causes the coolant in the engine to overheat and the temp gauge goes into the red. Once the air pocket moves out of the water pump the coolant starts flowing again and the temp gauge drops to normal. To see if this is the problem try this.
Get the engine up to operating temperature. With the engine idling slightly loosen the upper radiator hose clamp. Take a small flat bladed screwdriver and slip this between the upper radiator hose and the radiator hose neck. Allow the engine to idle until that all that comes out of the upper radiator hose is a steady stream coolant. Remove the screwdriver and retighten the hose clamp.
Doesn’t the coolant move too quickly through the system to cause a loss of heater temp? Sometimes I won’t have heat for 3 or 4 minutes. If I try your suggestion and I get coolant immediately, do I close it off or wait to see if air comes out later. I don’t want to waste too much coolant.
The heater core in your van is the highest point in the cooling system. If there’s air in the system it will collect in the heater core and you’ll get no heat. Once the heat starts working the air has moved out of the heater core and moved somewhere else in the cooling system. And if it gets to the water pump it can cause the coolant flow to stall.
When you go to purge the air out of the cooling system using this method, it’ll be pretty evident if there’s air trapped because no coolant will come out of the hose, just air. Once coolant starts coming out of hose, you don’t let it continue until a gallon has been pushed out.
Just FYI, there is a good chance that it will be near impossible to get at that upper hose & clamp in a reasonable way to do this (I have a '00 Silhouette). There should be 2 bleeder screws on the upper hoses that you can use. Of course, you could also take it back to whomever installed the thermostat.
Thanks for the tip. Just to add to the information, I had the thermostat changed, hoping it would solve this problem. The mechanic was not sure it was the culprit, but id sis settle the temperature gauge down some. His next guess was that the intake manifold gasket was bad. He didn’t explain how this effected the cooling system and I was looking for a better solution or confirmation that this could be the cause. I really don’t want to spend $500 to replace a $16 gasket.
The gauge only goes to hot for a few seconds and then returns to normal.
This suggests to me an electrical problem.
How would that relate to the loss of heat from the heater if the temperature gauge is falty?
An electrically operated air door could be closing.
I was actually wondering about that as well and whether or not the OP should at least have the temp sensor & circuit checked.