I recently purchased a 93 3.0 4runner with a 5 speed. When I first got it march the weather was nice and cool (Washington state) Now that the summer is finally here and the temps have been reaching the ninties, I've notice that the vehicle will start to overheat while driving at freeway speeds? If I slow down and hit the side streets, or stop and go traffic, its runs normal (halfway on the gauge). I've replaced the thermostat thinking it was sticking open and not allowing the coolant to slow down in the radiator to cool off; but this did not change anything. I'm thinking of replacing the fan clutch? Vehicle is all stock and still has the fan shroud. Could it be a radiator (although it looks clean; brass top tank)?

 

call toyota and see if the head gasket service was done on it !

 

Will they honor the head gasket recall if it still has not been done?

 

yes i believe the will ive even heard of them replacing the motor but its a start to call them and make sure

 

The fan is for low speeds. The fan goes to sleep at highway speeds. You have a radiator problem or a radiator hose collapsing if its old or of poor quality. Usually its the lower hose. I would junk the clutch fan and install a flex fan along with a new OEM thermostat and a new radiator. But, have a radiator shop chemically test your coolant for exhaust gas presence. If the test is good, spend the money on a new radiator and you will fix the problem. The amount of highway speed air flow and low differences in temperatures is too much for the old radiator.

My $0.02

 

hmm... the fan is for low speeds? hardly.
the fan is for engine speeds where the airflow caused by the forward speed of the truck is less than the amount of air the fan can pull across the radiator.
If your temps are acceptable at city street usage but overheats at highway speeds, get your radiator flow checked, if you're sure your thermostat is working properly.

 

Your 3.0 radiator "should" be ample enough to cool the engine without the assitance of the fan. That being said, its perfectly fine for the fan to be going at hwy speeds. I would advise against replacing your crank driven fan with a flex fan. A crank driven fan will out perform 99% of the aftermarket junk electric fans. Only use them if space is at a premium.

I would defantly drain and replace your coolant with RED toyota coolant. Don't use any other kind. I would also consider replacing the radiator if you can afford it. Also, when was the water pump changed (if you know)?

 

i had the same problem with my truck but it was easily remidied with a new rad. half my fins were missing. check your rad closer and see how its doing. possibly do a cooling system flush also.

 

suck it up and get the new rad. It will fix the problem, I had he same problem with the runner last summer. Good idea to check the HG history and COMPRESSION TEST is another good bet.

 

Any recommendations on radiators? I called performance radiator and they have two to offer. One is a metal tank two row, another is a high effeciency aluminum one row (plasic tanks). I've also checked ebay and there are three row metal radiators. Which would be best?

 

Aluminum is a great choice, but im not a fan of the plastic. What "metal" is in the other rads?

I would just go with an OEM equivilant...

 

the other tanks are brass tanks.

 

In order of thermal conductivity based on equal surface area exposed to air:
copper is highest
aluminum has approximately 1/2 the efficiency of copper
brass is about twice as bad as aluminum (aluminium? lol).
So.... can you tell me how much heat is being transferred by brass tanks??
I'd be willing to bet that whatever radiator you chose, if the tanks aren't plastic, they are brass.
So given equal suface exposure, a single row copper radiator is as good as a dual row aluminum radiator.
Have you any other questions?

 

May I add that the best argument for an aluminum radiator is not for its coolling abilities, but rather for its resistance to electrolysis and corrosion considering aluminum is self-annealing.

 

i snagged myself a plastic/aluminum and its worked just fine ever after 7-8000 miles on it so far.