Hey guys I have been cleaning out my garage an found alot of parts from when I use to build custom cars . I have a few of the 16" flex-a-lite electric cooling fans .
I know mechanical fans rob HP ... has any one done a electric fan conversion and was it a postive move or wasting my time by over engineering .
Thanks guys

greg

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1983 300cd

Time wasting. The engine fan does not "rob" significant power and the electric fans can't move anywhere near as much air.

I'm not sure I'd want to give up my regular fan. I've checked my fan clutch, which is working perfectly, my electric fan works too, and my car STILL comes home from work hot as a firecracker under there. 99ish degree air temperature plus road heat isn't doing the poor old thing any good.

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~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

What about the difference b/w the plastic fan and the aluminum fan? Negligable?

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In power draw, negligible. Airflow is higher when combined with the smaller diameter pump pulley.

The pulley and plastic fan are a good upgrade over the aluminum fan.

I haven't done it on a MB yet but a properly sized electric cooling fan has improved cooling and mileage on every car that I have done it to, including my mid 80s Isuzu diesel. If you can cool an inefficient gas V8 with an electric cooling fan, you should be able to cool a 5 cyl diesel.

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Ron Schroeder
'85 300 Turbo Diesel 2 tank WVO
'83 300 Turbo Diesel 2 tank WVO
Some former WVO vehicles since ~1980:
'83 Mercedes 240D
'80 Audi 4000D
'83 ISUZU Pup
'70 SAAB 99 with Kubota diesel
'76 Honda Civic with Kubota diesel
'86 Golf
Several diesel generators
All with 2 tank WVO conversion
LI NY

What kind of gains are realized?

Is this due primarily to operating temp or just the lost effort on on the crank?

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None. The only gain realized is the mental satisfaction of "accomplishing" something that didn't need to be done.

None. The alternator draws power from the crank same as the fan. There is no MPG gain and no measurable power gain. All it does is stress the alternator.

I agree ^^ hopefully he can back up his claim.

The more you transfer energy from one form to another, the more the losses are compounded.

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depends on what type of driving you do... I did a 7k roadtrip in an '84 300d, I removed the mechanical fan and installed a pusher electric fan, Since I was on the highway 98% of the time I only used the electric fan a handful of times.

I would not recommend it for a vehicle that spends a lot of time in heavy traffic, idling, A/C, etc.

The mechanical fan loads the crank all the time, even with a properly operating fan clutch, an electric fan only loads the engine when it is actually running.

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Cheers,
Robert

The disengaged fan draws less HP than the power steering pump consumes all the time.

You would gain more power and economy by switching to a manual steering box.

I was told the fan "robs" between 3 to 5 hp and 2 mpg and also waterpump life could be a factor .
I have yet too the factory electric fan come on yet ...the one on the front ? Under what conditions should that come on .
Thanks guys

greg

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1983 300cd

I find it impossible to believe that 3 to 5 hp is significant... except maybe on a 240 on an interstate. I also find that mileage figure difficult to believe. But maybe it's true.

The fan comes on when the air conditioning system calls for it, and when the temperature sensor in the engine calls for it.

AFAIK it doesn't come on unless the car gets too warm using just the mechanical fan. Isn't the switch-on point 105 degrees c or something?

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

The first vehicle that I converted was not for power or fuel economy reasons. It was because the engine got too hot in stop and go driving. I used a thermal switch to control the fan and I had a light on the dash to tell when the fan was running. Rarely would the fan run when I was traveling over 25mph and the car no longer overheated. This was on a 77 Camaro.


If I had run the electric cooling fan all the time, my fuel economy would have been worse with the cooling fan because of the added load from the alternator.

My Isuzu, my Kia Sportage and my military truck all came with mechanical fans. The Isuzu picked up about 5% both in town and on the highway. The Kia picked up only a tiny bit in town but at least 10% on the highway. The military truck picked up more than 25% on the highway. Mostly because of the high RPM and it didn't have a fan clutch. It also picked up at least 10% in town driving because with the mechanical fan, it never would get to operating temperature unless it was at idle for a long period of time in hot weather.

__________________
Ron Schroeder
'85 300 Turbo Diesel 2 tank WVO
'83 300 Turbo Diesel 2 tank WVO
Some former WVO vehicles since ~1980:
'83 Mercedes 240D
'80 Audi 4000D
'83 ISUZU Pup
'70 SAAB 99 with Kubota diesel
'76 Honda Civic with Kubota diesel
'86 Golf
Several diesel generators
All with 2 tank WVO conversion
LI NY

Not on any W123 or W126 models.

I remove my fan in the winter and have done so for the last 5 years. It has never given a gain in economy.