Rad fan removal?

[psyshack]

Ive pulled the belt driven fans off several cars in my lifetime and replaced them with electric fans. The first few cars I did this to the water pumps failed shortly there after. Best I could figure was they were on the way out. Or the sudden load change on the bearing in the water pump caused it to fail. On cars that I put electric fans on and changed the water pump at the same time did not fail.

I want to put a electric fan on my worthless Ranger. But wont do it untill I have to open it back up to put its second timing belt on. I didnt change the water pump the first time. I should have done it then.

psy

[dieselbenz]

I replaced the clutch fan on an 89 volvo 240 automatic with very good results. From the factory the clutch fan is mounted directly on the water pump shaft and powered by 2 V belts. The main problem with this setup is the weight and out of balance inertia of the fan tends to murder the water pump bearing in 60k miles or less. With clutch fan removed, the water pump has been known to last as much as 150k miles. After the e-fan installation city fuel consumption went from 19 to 21mpg and highway from 23 to 25mpg tested over many fill ups. Both city and highway mileage are above the advertised EPA numbers. I'm convinced.

[ELF]

Originally Posted by Sludgy

I'm curious why auto manufacturers often use an electric fan, but not an electric water pump. They could use the same motor to drive both.

It's common practice in V-8 race engines to use an electric water pump in order to eliminate power losses at high rpm. It seems to me that short-trip FE would benefit greatly from an electric water pump, because the water pump wouldn't turn on until the engine reached operating temperature.

My car has both, I'm not sure exactly how it works but, I assume the mechanical water pump spins slowly, Turns at lower speeds than a normal water pump so there is less drag on the engine, then I think the electric pump kicks in when things start to get hot. Again I have no idea if this is correct but it seems to be the only logical reason they would have both.

[brucepick]

Reducing the mechanical energy needed to run a pump has to be a good idea.

I do think a pump needs to be running always to distribute the heat through the block. Otherwise you'd have localized hot and cold areas, much more than there are in engines with pumps working. But you probably could run the pump(s) at lower speeds much of the time.

Reliability is the other concern I have. Existing water pumps are pretty simple and any failure is still a bad thing. Added complexity for clutch drives or electrical or whatever would have to be done without reducing the reliability.

[GasSavers_BluEyes]

I have been told that most electric water pumps do not generate enough flow for street use. I have primarily seen electric water pumps advertised for drag racing where you can shut the pump off for a 1/4 mile run then let it run while the engine is off in the pits to cool back down. Not many electric pumps listed in dirt-track catalogs where the cars must run for long periods of time. Electric pumps also have a rated hour life that is far less than the life of your average mechanical pump which probably makes automakers weary of putting them in.

I doubt there will be much gain from running an electric water pump though. The pump is something that needs to be running all the time to keep temperatures even. It takes power to run the pump and either way that power is coming from the engine.

[BeeUU]

Due to an electrical issue the electric fans on my Peugeot were running at full speed all the time, creating alot of drag on the alternator. Fortunately, the fan controller is in the passenger compartment, I know leave the fan unplugged untill I need to use them. It has created problems when my wife has driven the car, she does not remember to check the temp gauge as often as I have learned. There has been a couple of steaming events!!!

I think that the new BMW 3 series has an electric water pump. I will try to find the reference.

[BeeUU]

I forgot to add that for 98% of the time the fans are not required. Only during the summer in stop and go traffic are they really required.

I will confirm what beatr911 stated, after sitting at a traffic light and once you start moving that coolant temps fall pretty fast, even at slow speeds.

Although now that I have the grill taped, temps rise more quickly and the temp takes longer to fall!!!

[BeeUU]

Attached is a link that states the BMW is using electric coolant pumps on thier engines NOW!!

Also on the one series they have active flaps to close off the grill!!! I have heard this is true on some Mercedes cars as well.

Coolant pump ref:
http://www.greencarcongress.com/2007..._offer_in.html

1 series ref:
http://www.greencarcongress.com/2007...ces_.html#more

[MetroMPG]

Originally Posted by BluEyes

I doubt there will be much gain from running an electric water pump though. The pump is something that needs to be running all the time to keep temperatures even. It takes power to run the pump and either way that power is coming from the engine.

But you're assuming that the pump would run the same amount and at the same speed that a belt-driven pump runs.

One advantage is that you don't need to run the pump when the engine is cold. Until the engine warms up, it doesn't run (or runs slowly), which speeds up warm up times.

At cruising speeds, the extra airflow through the radiator means you can slow the pump down.

The benefits come from intelligent control. Just like the with a "smart" alternator.

[MetroMPG]

I look at it like grille blocks: cooling systems are designed for worst case performance.

I suspect there's lots of wiggle room with the pump for people who don't idle their cars in Death Valley with the air conditioning on.

(Can you tell "electric pump conversion" is on my list of mods? It will be a particularly good FE benefit when running the electrical system without the alternator.)