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Jim Grant's Tech Tips'94 Ford Taurus
Q:
My ’94 Ford Taurus gives off heat sporadically. I have heat, and
then suddenly I have no heat and the temperature gauge shoots up into
"h" for hot. I pull over, it cools down and I get heat, then
it starts acting up again. I have had it in for servicing: They changed
the thermostat twice -- problem not solved. They changed the water pump
-- problem not solved. Now they suggest changing the head gaskets although
there is no leak. The antifreeze looks clean (no filmy spill). I said,
“No” to changing the head gasket just for the heck of it (over
$1,000). I took my car to another garage. They said there might be a door
to the heater that is not opening when it should be ($800 to fix it).
So, do I go that route or have the head gaskets changed or try to figure
out something else? I think if it was the head gasket, I would not get
heat at all and the motor would always run hot.
A:
The
loss of heat with a temperature gauge that goes hot at the same time is
a good indication that air is getting into the cooling system. With the
repairs that you have had performed it is likely that the source of that
air is due to a head gasket problem. A bad head gasket allows combustion
gases to enter the cooling system. These gases displace the coolant. Depending
on the vehicle design this air can become trapped in different areas.
For example, your heater core. As these combustion gases/air builds up
in the cooling system they displace the coolant and interfere with the
circulation of the coolant. This results in an overheating engine and
the loss of heat from the heater. As for the shop saying that it might
be a door in the heater not opening, not likely? Why is that? The doors
in the heating system only direct air from the heater based on the selection
you make. These components could all be broken and never cause the engine
itself to over heat. If your problem is that pronounced you should be
able to have a chemical check performed on the cooling system. The chemical
used reacts to the presence of combustion gases. If the chemical changes
color then there are combustion gases entering the cooling system. If
that is the case, you’ll likely need head gaskets and some machine
work.
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