HIGHWAY OVERHEATING- any suggestions?

[roadwarrior]

My 93 camry wagon is overheating on the highway after about a 30 minute drive. Has a new radiator, thermostat, antifreeze. Turning on heater drops temp to near normal. can sit and idle without over heating at all.
Any suggestions whats wrong. Dealer did "Hydrocarbon"
test, said head gasket ok ( that was their first guess as to the problem) car has 126k miles, runs well, plenty of power.Am totally baffled! Help Help Help!

Bill, wb2cuk2000@yahoo.com

[Hajoca]

On the highway, the rad fans do not do much. Rule them out.
Air in the system might be your problem.
You say that the heater helps... so I was wondering if there ia a blockage in the water pump to thermostat to radiator section?

did you do this work yourself?

[ghettosled]

i was thinking a blockage as well. have to tried to flush out the engine?

[Gary_602Z]

How bad is it overheating?
Is it loosing coolant anyplace?
Was it overheating before you reolaced the radiator and t/stat?
How does the car run otherwise?

Gary

[marc780]

Yeah maybe the other people are right. Perhaps it needs to be burped. Remove radiator cap, run engine, until thermostat opens (youll feel the water rush at upper hose). Sqeeze hose several times

If that doesnt work you can loosen the hose clamps at the heater hose (the upper hose). Run engine til coolant drips out. Tighten clamp.

[jhbhatia]

^^ burping would mean you need more coolant, that sould tell him. i think its something else!

[marc780]

1. Has anybody checked the water pump? If it aint broke then maybe the timing belt is loose and slipping?

2. Maybe the cooling passages are clogged, have you ever used a stop leak like aluma seal or something.

3. Igntion timing? If its off it could make the engine run hot although you would probably notice the difference in performance.

4. A large dead bat epoxied over radiator fins. (Jk.

[ToyotaToday]

you should be able to see if there is a blockage in the fluid system just by touching the different hoses. When you are running the car, check to see which hose is hot and which ones are cool (relatively). If the system is running normal all the hoses should be about the same temperature as the cooland circulates. Of course, you need the run the engine until its hot, so the thermal valve opens (if it's working properly).

[douglasellen]

Also check radiator fan to make sure it is rotating fast enough and is working at all.

[ToyotaToday]

Originally Posted by douglasellen

Also check radiator fan to make sure it is rotating fast enough and is working at all.

I don't think the radiator fan would be the problem for this situation as the engine is overheating on the highway. Driving on the highway has more than enough air cooling the engine. Usually in "bumper to bumper" traffic or the car is stopped is when the radiator fan would turn on. The coolant must not be circulating throughout the whole system. Some kind of blockage or thermal valve is not opening automatically

[nitrous3sfe]

Was the water pump replaced with the timing belt at 90 or 120K miles? My toyota is cool as a cucumber at idle, but runs much hotter on the highway. For me its the water pump, which I will be replacing soon. Sounds like this could be for you too.

[Kep]

Nitrous3SFE,

Good to know. How did you determine that it was the water pump?

Kep

[Klutch]

Backwards thermostat?

[Dave's]

Engine cold, remove cap and start engine. Within 10-15 minutes the coolant should start flowing visibly. (If you aren't sure what to look for, try on a similar car which works properly.) If not, the pump is bad or there's something blocking coolant.