Oh, BTW, I ran it most of the time in 5th, and the temp came down a
BIT. Going into 4th caused it to head back up toward hot, but it never
got down more than 4.5/5ths toward Hot regardless the gear I was in.
How do I check the -- what is it -- the temperature sensor?

HarryTruman

HarryTruman

do a chemical flush and also a power flush of the cooling system, and
most importantly, clean the radiator, and if the car has A/C remove
either the radiator or the A/C condenser, whichever is easier, clean out
all the debris that collects between them, and check both the radiator
and the condenser for bent fins and "rake" them straight again if necessary.

good luck,

nate

Coolant full, radiator fins clean, not more than 50% coolant
concentration, check/replace thermostat.  If all else checks out
replace the radiator with equal or enhanced capacity.  "All metal"
radiators sound good but are not as efficient as aluminum/plastic.

Loses additives that protect against corrosion.  Still conducts heat
the same.

Beware an excessive coolant concentration -- you car will run hotter
with significantly more than 50% coolant in the mix.

Radiator fan has no bearing on freeway engine temperatures.  Only at
slow speed.

Don
www.donsautomotive.com

heating up at high speed and going down at lower speeds is usually an
indication of insufficient flow...I'd replace the thermostat and have
it flushed. If you were using the A/C (I'm sure you are), the fan(s)
should run all the time.

But the fans are not a factor once the car is moving at any speed. So
if you weren't running hot sitting at a red light or something, that's
not the issue.

A badly worn water pump impeller can do this too, but that's pretty
rare.

Adding to previous comments:

Make sure your oil is fresh and rated for your conditions. (Check the
manual.) Have it changed if you aren't sure. Keep the oil topped up.

If the car seems to be overheating, turn the car heater on full.
Yes, it will make it very uncomfortable inside. (The A/C is off already,
right?) The temp should drop with the additional cooling capacity.

A high temperature may be normal for your car under those condtions.

Dan

(This account is not used for email.)

Make sure you only use a 50/50 mix with water.  100% coolant doesn't
cool as effectively.

Is the front airdam still there and still in one piece?  Some cars like
82-92 Camaros WILL overheat if you lose the airdam.

The wife's Beretta had a broken one for years, I finally cut the rest of
it off... the temp went up "one tick" on the digital dash - still
normal, but definitely warmer - it used to always be 3-4 "ticks" on the
gauge, now it's 4-5 ticks.

Ray

It loses its ability to prevent corrosion but not to prevent
overheating or freezing.

Use the same type of coolant that you originally had, and don't switch
to Dex-cool (red-orange) unless that was what you had because it can
dissolve deposits left by other coolants and turn soupy.  Don't use a
flushing chemical unless you're prepared to replace the water pump
since those chemicals can dissolve deposits that have been plugging
leaks.  Some water pumps are driven by the timing belt and can be
difficult to change.

If your hoses have more than about 6 years or 75,000 miles on them,
replace them. and use molded hoses, even for the heater hoses, not
accordian flex hoses, which crack much more easily..  If you replace
any spring hose clamps with screw clamps (you may have to, because of
tight access),  retighten them after a week, and check them at every
oil change because they don't seal as well as spring clamps or
heatshrink tubing and loosen over time.  I would also replace any old
radiator cap because cracked rubber in it can cause loss of pressure
and overheating.  Get an original equipment cap, not an aftermarket
one.

That works.  Also it should run continuously when the A/C runs.  Some
cars use a bimetal switch screwed into one of the radiator tanks to
control the A/C, and you can jumper it to check the fan and any relay.
Other cars use a thermistor, either screwed into a tank or a fitting
inline with one of the radiator hoses.

When the coolant was last changed was it mixed with the proper amount
of water?  If the individual didn't use pre-mix but installed undiluted
coolant concentrate it will not transfer heat effectively.  Have
someone check the coolant for proper mix.

Another and more likely possibility is that heat is not being removed
effectively by the radiator at high speed.  I would have the radiator
on your 16 year old car checked to see if it is partially clogged and
restricting the flow of coolant at high speed.