Cooling fan concerns

[jbarth]

I have a new $500 '86 non-SR5, with only 156k that had some simple issues. The steering u-joint had seized and was very hard to move, my buddy and I put it in a vice and worked it loose with WD-40. Also, it probably had the original fuel filter that was pretty well clogged. It has a few dents all around and a little rust under the trim on the drivers rear quarter.

The first drive invoked great concern for the condition of the motor after it overheated, but I soon realized the issues are related to low speed cooling capacity. I also think it had straight glycol in it. After flushing a few times with water and then last with a bit of chem. flush the overheating only happens in slow moderate to high load conditions. I live in Montana, on top of the continental divide, the terrain is rugged and I often find myself powering up a decent grade in 1st and 2nd gears. This is the only situation that leads to overheating, otherwise it sits at about 1/3 on the gauge. If I notice it getting warm and keep the load low it cools fine (idle up hill in EL or 1st) or if I go faster and move more air it is fine.

The issue is with the fan pulling air out of the engine bay, at anywhere between 5mph and 25mph the cooling fans flow is negated by the force of the air coming into the grill. (That and a clogged old radiator maybe)

So to the question, what direction should the fan move air, into the engine bay or out? I can tell by the cooling fan drain hose pointing up to the left it has been monkeyed with, I just wonder if the polarity is correct (what is the factory airflow direction?). Or do I need a new radiator.

Thanks,
Josh

[takza]

The fan works with the usual airflow...the air moves thru the radiator towards the engine. Not sure how you'd get it to run backwards.

That steering joint probably needs some light oil now and then to keep it flexing.

[4wdchico]

A new Koyo brand rad would be a good idea if your current rad is suspect. If you disconnect the wire from the fan switch on the lower rad tank, passenger side & the key in the on position the fan should run and blow air thru the rad.

Some more info that may apply to your cooling situation: http://www.tercel4wd.com/forums/viewtop ... f=2&t=5560

[Petros]

welcome to the list!

Sounds like you have limited cooling capacity, that could come from several sourses. Also, does the temp come down when you turn on the heater? That is a sure sign of limited cooling capacity (and a short turn stop gap until you get it fixed).

Be careful, these engines to not take well to being overheated, if it got to the red zone on the gauge it now likely needs a new head gasket. there is a design flaw in the head that does not allow for even cooling, and overheating it causes the bond between cyl 1 and 2 to fail. There is a simple fix by adding a few coolant holes in a new head gasket if you have to pull the head off.

I would flush the radiator, replace the thermostat (get a good one, not the discount version), verify the fan is working properly (including the temp sensor), and your lower rad hose is not collapsing when at high rpm (an old hose can break down and not handle the vacuum on the water pump suction side).

Also you might verify you actually have the double row radiator, the single row came in the 2wd sedan version of this car and is interchangeable, many often replace an old radiator with the single row one since it is more common and less expensive. If everything else is working good the single row will still cool it fine, it just will not have any extra capacity for a fully loaded Tercel4wd on a hot day.

Also realize that the fan adds no cooling capacity when the car is moving faster than about 30 mph, it only adds ariflow at low speeds or when stopped. If it overheats on steep hills where you are moving faster than 30 mph, than it is not the fan.

Good luck.

[keith]

Before you go out and buy a new radiator or go through the pain of replacing the thermostat, replace your radiator cap. The symptoms you describe are most often caused by a radiator unable to hold pressure.

[jbarth]

I appreciate the responses. They are great, but make me realize how much I left out.

I did replace the rad. cap.
Any grade, any load, any speed the car cools when I turn the heater on.
The fan does come on if I have the key on and unplug the radiator temp sensor.
The hoses are fine and do not collapse at high rpm. Moderate rpm, low load, actually seems to increase cooling capacity, due to the increased circulation.

So can I get a second to the notion of the fan blowing hot air out of the grill and forward, as being retarded?

Can someone tell me yet again this is not the stock configuration, and that every other 4WDTercel the fan blows outside air into the engine bay. I think this could be the whole problem, pulling hot air through the hot radiator.

Also, can someone show me some pics of the single vs double row radiators?

Thanks

[Neu]

The fan does come on if I have the key on and unplug the radiator temp sensor.

Your temp sensor is out. They'll either stay on all the time or not come on. Just goto the junkyard and grab one.

[4wdchico]

Googling this: double row radiator core picture

got me this as the first result: http://www.google.com/images?hl=en&clie ... 24&bih=658

ckeck out the second image from the above: http://www.google.com/imgres?imgurl=htt ... CCAQ9QEwAQ

[Petros]

fan blows from front to back through the rad, I do not know how you could have it blowing backwards, short somewhere? Check your wiring for damage. I would jump hot wires right to the fan connector as a test for fan rotation direction. A shorted sensor? Previous owner mess with the wiring? If the fan motor itself has an internal short it will not spin fast enough for adequate cooling when the car is not moving.

Air going either direction will still cool it, but at slow speeds the fan will be blowing against the incoming air from the forward movement of the car, preventing cooling. Better correct that first before you do anything else.

The double row radiator is about 1.25" thick, front face to back face (you can see the thickness on the edge of the core), the single row is about 0.75" thick. The single row will cool good enough for normal driving if everything else is working properly, it just does not give you any excess capacity.

Good luck.

[Highlander]

You might also check on the under carriage tray- the 'splash plate' as some refer to it- it helps limit the amount of air pressure in the engine compartment, helping to suck air through the radiator.
The fan should only be on if the radiator is hot, unplugging it should also make it come on. Double check (I think there was some confusion in your post on this) it with the engine cold and the fan switch disconnected, the fan runs with the ignition on, Right? Then with it plugged in, the fan goes off, correct? If this is so, the switch is working fine.
I had a similar problem with the sunroof '85, it turned out to be a massively plugged radiator- it weighed about 2 lbs more than the new one- and yes, it'd been flushed with chem and water, etc.- Who knows what water (sludge) was put in it when it was on a ranch in Wyoming?

[Petros]

I learned the hard way on water in the rad. I had to replace an otherwise perfectly good radiator in our Mazda MPV after I used our well water on it for about 4 years. No chemicals in the well water, but lots of dissolved calcium in suspension. When the water cools in the tubes, it coated the inside of the tubes with hard calcium deposits that precipitate out of suspension, plating the inside of the rad. Chemical flushing did not help, I even tried hydrochloric acid on it. I had to buy a new one for big bucks.

Now it is only distilled bottled water (and antifreeze) for all our radiators. I get it reclaimed antifreeze mix from the local wrecking yard for $1 per gallon, cheaper than distilled water!