I have a 1998 Ford Taurus SE 6cyl 24 valve Duratec with about 135k miles on it. It has started to overheat. It has a closed system with the thermostat on the bottom passenger side. It isn’t leaking coolant but it does boil when it heats up and you can hear it whistle/pop around the overflow cap. I have drained the whole system using the petcock valve and have changed out the thermostat (which because of its location requires all the fluid to be changed or you get green rain). So, new thermostat, new coolant, still overheats. The defroster air is blowing cold. It has a belt driven water pump but I haven’t touched this. Both electric fans are working.
I don’t see anything in the oil. It is still a nice dark color, not milky or anything. I saw no oil in the coolant I drained. When it first starts, there is a few seconds of puffs of white/gray smoke but it is very light and goes away quickly. There is no water running out the tailpipes.
My question is, what is your guess on the cause? I’m at the point with the car, with its age and miles that I’m not willing to dump a lot of extra $$ into it – so there will be no head gasket change – but don’t want to junk it if its something simple. I do most of my own work on my cars.
Do you have any guess on the cause? How can I diagnose it further? Should I just change the water pump and if that doesn’t work then what? Or anything you can think of would be appreciated.
If it is blowing cold and not heat, you have air still in the system and it needs to be bled. It will overheat with air in the system. Also, does this have a radiator cap? If so, change it.
A pressure test might be a good idea. Overheating can be caused by lack of pressure and if applicable a check of the flow and control valve to the heater core.
I am guessing it could be a defective water pump. I think these pumps have a plastic impeller that can come loose or break off the pump shaft. But as Barkydog suggested have the cooling system PSI checked first to rule out any bigger problems.
There’s lots of things that can cause a car to overheat. If this was my car, I’d try a new radiator cap. If that didn’t fix it, off to the local radiator shop. They diagnose this all the time.
Its a closed system so no radiator cap. Tried again last night to get air out of it but it didn’t change anything. I guess I’ll try water pump and after that junk it.
But it has an overflow cap, right? And that’s where you hear hissing? I’m not sure what it is in your car, but there has to be some gadget – in most cars it is the radiator cap – that is holding and controlling the coolant pressure. The coolant pressure must reside in a narrow psi range or the cooling function won’t work correctly. If that something fails to hold pressure correctly, coolant boiling is the result. My early 70’s Ford truck did this one time, overheating, I could hear the coolant boiling, heard hissing from the cap area, and changing the cap to a new one fixed the problem straight away. That gadget failing could be the only problem you have, whatever that gadget is on your car.
Also, the radiator may just be plugged and you need the existing one cleaned or replaced. Again, a relatively minor problem.
Maybe an expert here could educate me on how the coolant pressure is set in this type of cooling system. The volume of a built-in air pocket? What?