Re: Converting from belt-driven fan to electric fan

There probably is not much of a difference in parasitic loss between a belt or engine driven fan and electrically driven cooling fans. Electric fans cost more to install than one mounted on the front of the engine, but they are pretty much the only choice for vehicles with transverse-mounted engines, since a fan at the side of the engine compartment wouldn't do much.

On my previously owned BMW E34, it had the belt driven fan and 2 auxiliary fans. I hear the auxiliary fans turn on many times that's why I assume that the aux fans do most of the work. The aux fans had a normal and high speed. I do remember replacing my fan clutch years ago. I was thinking the fan connected to the engine didn't work as much so as not to draw power from the engine. My aunt had a Toyota with a 4Y engine many years ago. I'm pretty sure it had both belt fan and aux electric fans but I'm not sure which fan did much of the cooling. However since they are called "auxiliary" I would assume they are just for supplemental cooling.

Obviously, designers use auxiliary electric fans if the engine-driven fan doesn't move sufficient air through the radiator and/or air conditioning condenser. You would probably see this arrangement if the radiator and air conditioning condenser has a relatively small surface area, like when the front opening is small, especially in cars with air conditioners.

I believe that in the U.S., the Toyota 4Y engine was used in the first generation vans and is still used in forklifts. I doubt if your aunt owned a forklift, so I'll assume that she had the first generation van. The first generation van had a mid-engine layout mounted behind the front wheels, under the front passenger seats. The location meant that an engine-mounted fan would not draw air through the radiator, so additional electric cooling fans were mounted on the radiator to draw air through it.

Most of the auxiliary fans are there to provide better airflow over the AC condenser unit than the engine driven fan can provide at lower speeds. They are also used in vehicles that have poor airflow characteristics due to the body design or aerodynamic styling. On vehicles with small engines they are also used to save some engine power.

Hmmmm...I mentioned before this is the only 'beater' I have that has a working R-12 A/C.

It's also the only beater I have that won't see roads in the summertime (the plate will be coming off it and going back on the Supra...)

So, it's a Winter-only car. I really don't need a fan running all the time, and when you stop the car for a while and leave the engine running, it really draws down the engine temp...almost to cold. So losing the belt-driven fan won't really be too hard to take. I bet the thing hasn't 'turned on' for at least two weeks...

hahaha. The 4Y engine was on a RWD Toyota Crown and not a minivan and much more a forklift.

Sounds like your fan clutch, thermostat, or possibly both are sticking. I havn't tried it on a Subie but on my Explorer the fan clutch is easy to test. With the engine off and cold you should be able to turn the fan with your hand. With the engine off and warm you shouldn't be able to turn it. I'm with the others in saying that switching to an electric fan doesn't seem like it would buy you over the existing system assuming it were working properly. I also don't see why you would gain any milage since the energy to turn the fan still needs to come from the engine but now with an extra conversion to electricity at the alternator and then back to mechanical energy at the fan motor. Every conversion will lose you some effeciency so I'd expect the electric fan to actually use more gas rather than less.

That's what the clutch on the engine-driven fan is for.

Then fix the THERMOSTAT instead of spending all the money for an electric fan. The fan isn't what's making the engine get too cool, its a bad thermostat.

But even with the clutch, the fan is always spinning. It never completely stops. And with the weather here being in the single digits, air movement other than from driving is not required.

Thermostat's cool. When the car is running at a constant speed, or even stop and start driving, the temp satys rock-steady. Only if I park for more than 2 minutes does the temp drop.

At these temps, it seems even airflow from the fan idling is enough to cool the engine.

Ahhh yes, but when you are forcing air through the radiator in excess of what the fan draws when not moving, the fan is not drawing much power, it is more like a windmill at that point. Again, if you have a properly operating viscous clutch, the fan isn't going to draw significant power. There is a certain amount of drag from the clutch that causes the fan to rotate, but the power draw is tiny. If you want to get into diagnostics, you'll need a variable strobe light. You adjust the strobe until the fan appears to be not moving and then compare that rpm to the engine rpm.

It still seems to me that there is a problem with the thermostat. Have you verified operation of the fan clutch? One possibility is that the clutch is frozen. There really should not be much difference between idling and driving at moderate speeds as far as cooling is concerned. I am surprised that the fan over-cools the car at idle, but you don't experience over-cooling car when cruising at a steady 35 mph. Have you actually tested the thermostat, or are you just assuming it is OK because it seems OK when the engine is under load. It is possible that the thermostat does not completely close so it cannot regulate temperature at the low end. For the cost of a thermostat, I'd try a new one before going overboard and installing an electrically operated cooling fan.

Ed

The proper and working thermostat will 'close' and force the engine to stay at it's setting of say 195F when you slow down the engine so you keep the heater working, a broken thermostat will allow the engine to cool down so you lose internal heat.

I just changed one like that in my Jeep and in a friends car, they were broken 'open' so we couldn't keep heat up.

Thermostats are backward to what some think, they set how 'cold' an engine can run, not how hot.

Mike

That's deceptive, though. Aeordynamic forces usually increase as the cube of velocity, so while the fan may appear to be spinning fairly fast, it may be drawing virtually no power from the engine. The loudness of the fan is a better indicator- on my car the fan will roar quite loudly at fast idle, then go completely silent when the clutch disengages.... but the eye can't really see any difference in the speed of the fan.

Then the thermostat is BAD. The temp should never drop if the thermostat is doing its job. That's the whole point. What its probably doing is sticking open rather than closing smoothly as the temperature of the engine decreases. When the engine finally gets cold enough it will snap shut, but that's not how its really supposed to work.

I don't doubt that. But the problem is still the thermostat if the engine temperature falls below the normal operating temperature once its gotten up there in the first place.

I agree with the sticking thermostat idea mostly but no one has mentioned that the engine block itself does lose heat as it is a large chunk of metal with cold air flowing over it. The outside temp at which the t-stat is fully closed but due to heater core and direct heat loss the engine starts to cool down below normal operating temp varies and is usually well below 0 F but it is still a very remote possibility.

The Crown hasn't been sold in the U.S. for quite a while, and it had a M series engine back then. Obviously, your aunt isn't in the U.S.!

Well, I think whatever is going to have to wait! Although I will try the thermostat. I didn't *think* of being stuck *OPEN* !!!! :0

I took it to have the timing belts replaced. Timing belts are almost new...

Head gaskets are leaking...

Looks like Steel Seal for this one!!!