2001 Kia Spectra Overheating--Need help with troubleshooting

I have a 2001 Kia Spectra, 1.6 L 4-cyl engine, 55000 miles. It
overheats at highway speed ( above 55 MPH) after about 5 to 10 minutes
driving. I can stabalize the engine temperature by turning on the
heater full blast and hitting the "recirculate air" button. No
overheating at idle. Here's what I've checked:

* No obvious leaks. I added maybe a quart to the radiator before the
level came up the cap. I've never opened the cap on this car before so
I don't know what the normal level is. Maybe there is a slow leak, but
there's nothing dripping.

* Both fans are working. Both kick on when I turn on the
air-conditioner.

* The top and bottom radiator hoses are both hot after about 10 minutes
idle.

* After about 10 minutes at idle, the fans kick on automatically, and
the coolent level in the radiator dropped. This means the thermostat
opened, I think.

* I felt the radiator with my hand and didn't find any cold spots.

I'm out of ideas. Maybe there is a slow leak. If the water pump had
failed, I'd see overheating at _any_ speed, right?

If anybody can help, please let me know. Thanks.

--
Rodney Dunning
Birmingham, AL

"Rodney Dunning" > wrote in message
oups.com...
> I have a 2001 Kia Spectra, 1.6 L 4-cyl engine, 55000 miles. It
> overheats at highway speed ( above 55 MPH) after about 5 to 10 minutes
> driving. I can stabalize the engine temperature by turning on the
> heater full blast and hitting the "recirculate air" button. No
> overheating at idle. Here's what I've checked:
>
> * No obvious leaks. I added maybe a quart to the radiator before the
> level came up the cap. I've never opened the cap on this car before so
> I don't know what the normal level is. Maybe there is a slow leak, but
> there's nothing dripping.
>
> * Both fans are working. Both kick on when I turn on the
> air-conditioner.
>
> * The top and bottom radiator hoses are both hot after about 10 minutes
> idle.
>
> * After about 10 minutes at idle, the fans kick on automatically, and
> the coolent level in the radiator dropped. This means the thermostat
> opened, I think.
>
> * I felt the radiator with my hand and didn't find any cold spots.
>
> I'm out of ideas. Maybe there is a slow leak. If the water pump had
> failed, I'd see overheating at _any_ speed, right?
>
> If anybody can help, please let me know. Thanks.
>
> --
> Rodney Dunning
> Birmingham, AL

If you overheat at idle, but not at highway speed, it is often an indication
that your
fans are not working.

Conversely, if you overheat at highway speed but not at idle, it tells you
that the
increased heat generated by the engine is not being adquately removed. And,
some
of the reasons a
(1) slipping water pump belt, or bad water pump
(2) radiator hose on the suction side of the water pump collapsing
(3) partially blocked radiator
(3a) check for bugs, grass clippings, mud in the radiator, particularly
between the
A/C condenser coil and the radiator face.. A blocked condensor coil
alone will
keep air flow from the radiator.
(3b) radiator partially blocked internally
(4) system not completely filled with coolant. Check radiator expansion
cap, fill system
properly to exclude air pockets, etc. If the system 'uses' coolant,
check for leaks
near hoses, at the radiator, from 'freeze' plugs, head gaskets, etc.

A blown head gasket, or cracked head or block will also cause overheating
and can,
in worst cases, be a bit tough to localize.

I may have missed a few, but this should get you started.