bye bye fan clutch - PeachParts Mercedes-Benz Forum

OhioSDL · #1 10-21-2004, 12:39 PM

My fan clutch on the 300 SDL seems to have a bit more play than i like. I d hate to find out at 5000 rpm how out of ballance it might be.

Has anyone attempted to install a low clearance electric fan and remove the clutch all together?

Hatterasguy · #2 10-21-2004, 12:50 PM

No I have not been tempted the factory system works to well. But I'm sure you could rig one up the problem will be keeping the engine at the proper temp.

OhioSDL · #3 10-21-2004, 01:07 PM

well yes, and with the fickleness of head in relation to overheating is the big issue. with my fan clutch being possibly comprimised i worry about that.
the benifits i can see with going electric as opposed with replacing the clutch is in fuel savings and cost savings.
i think its around 300 for a new fan clutch and for less than a 1/3 i could get a electric fan with a setable thermostat.

Im not worried about blowing the hot air off the engine as i dont have the bottom pan on the engine bay so the climate controled/heated bay will never be an issue.

From what i have heard the cooling provided by a fan is really most usefull from 0-15 mph. after that enough cooling is provided by air forced in through the front. so why waste energy pushing air around at 15-150 mph

Habanero · #4 10-21-2004, 01:15 PM

If the fan clutch is working properly, it is my understanding that the fan should be more or less free wheeling if the engine is cool enough, so it shouldn't waste any energy. Another consideration in calculating fuel usage is the efficiency of the electrical fan. The electricity isn't free, it has to made by the alternator, which isn't close to 100% efficiency. Add to that the fan motor itself isn't 100% efficient, and you are probably pretty close to the same energy usage as the engine driven fan. Would be interesting to do the calculations to figure out which was more efficient, but I think I would put my money with the engine-driven fan. Less "middle-men" so to speak in the energy conversion.

OhioSDL · #5 10-21-2004, 01:26 PM

but the electric fans only draw power when their thermostat says that coolent in the radiator is over Xdegrees. otherwise no power is used.
free spinning or not (and mine is not very free spinning right now) i would think that more energy is used in a mechanical fan than an electric fan.
this would apply to highway driving, the inverse would be true for city driving i think.

but than again are there any vehicles with out a waterpump/fan that are not front wheel drive?

sixto · #6 10-21-2004, 01:37 PM

What do you mean by play? Does it feel too easy to spin or does it wobble? If it wobbles, get it checked immediately. A wobbly fan quickly develops an appetite for radiators. And we're talking of an early 603 here.

Contact member ke6dcj (Neil) and ask what electric fan he used when he dropped a C36 engine in his 300TE. I think he replaced the front fan, not the clutch fan, though.

Sixto
95 S420
87 300SDL

Hit Man X · #7 10-21-2004, 02:04 PM

The amount of power e-fan(s) pull at lower speeds is very minimal when considering the load against the alternator. On both my trucks I run e-fans without a problem for over two years here in the Texas summer... which resembles hell in some aspects in temprature.

Now I'm using a variable speed fan controller from Flex A Lite, it's rated at 40A and has four heat sinks on it. There is a 25A version with two heat sinks also. Now the key with this controller is to run all 10awg power wire from the controller to the fan and whatnot. Prevent burn up.

Next, if you have the extra dough... get a better controller from www.dccontrol.com It's about $90 as opposed to ~$60. But it's a more solid unit. It's what I plan to upgrade my VSC's to in the near future.

Both controllers are variable speed, meaning they will soft start the fans at 20-50% power when they click on (20 for the DC, 50 for the VSC) and are fully adjustable from ~160° turn on to well over 200° both in deg Fah. AND you can also wire up full ON or full OFF switches to either units to turn them off when you choose.

Habanero · #8 10-21-2004, 02:23 PM

Quote:

Originally Posted by OhioSDL

but the electric fans only draw power when their thermostat says that coolent in the radiator is over Xdegrees. otherwise no power is used...

The same is true of the mechanical fans, if the clutch is working right. Only when it heats up and engages does it actually draw any power.

Hit Man X · #9 10-21-2004, 02:36 PM

Quote:

Originally Posted by Habanero

The same is true of the mechanical fans, if the clutch is working right. Only when it heats up and engages does it actually draw any power.

A friend of mine dyno'd gains on his truck between an unlocked clutch fan and a locked one. Pulling the unlocked fan with clutch yielded him appx 7rwhp yet over a locked clutch gained 17rwhp!

Pulling 5-7A at low speed from the alternator would draw nearly no power and even at a full load of 20A on a good fan, that's going to be similar to having your headlights on with your stereo.

Remember... you can fully turn off e-fans to there is no drag on the motor or alt.

Habanero · #10 10-21-2004, 03:11 PM

Now he needs to dyno with and without the lights and stereo on and we will have a comparison. Better yet, we need the same experiment done with a Mercedes. I always thought an electric fan would be better, too, but after dabbling in using alternative energy sources to turn an alternator, I learned how difficult they really are to turn. I really would be interested in seeing scientifically valid data (at least duplicate dyno runs, all variables accounted for) to see the difference.

Hit Man X · #11 10-21-2004, 03:21 PM

Well if clutched fans were so efficient, why aren't they used on most newer vehicles? Heck, GM went to e-fans on its 1/2 ton trucks for the '05 model year.

Pete Burton · #12 10-21-2004, 03:33 PM

Electric fans certainly have their place, but a mix of factors such as heat loads, reliability and resistance to change is probably why MB used the mechanical ones. To really be right, the airflow should be designed to the fan, shroud and surrounding components. I'm sure you could get it to work, but I don't see a big advantage. IMHO, I'd get a good used one for $100 or less and move on.

#13 10-21-2004, 04:14 PM

Quote:

Originally Posted by Hit Man X

Well if clutched fans were so efficient, why aren't they used on most newer vehicles? Heck, GM went to e-fans on its 1/2 ton trucks for the '05 model year.

Not to bash any specific auto maker,
but as far as simplicity, decent effeciency, reliability, and whatnot...mechanical over eletrical is the way to go. It all comes down to tinkering and things of the sort. Engines are getting so choked off with emissions crap and fuel guzzling designs that they probably run electric just so that nobody hears the loud fan noise and the lack of "seat of the pants" power.
I wouldn't compare my mercedes (old) to a newer electric everything car. Its like apples to rotton oranges.
I personally thought electric was a fantastic idea..
but a proper working mechanical was chosen for a reason
the mercedes people could have easy made a bigger electric fan but they didn't...
its an old diesel..
let it be mechanical

Habanero · #14 10-21-2004, 04:50 PM

I attribute the trend of newer vehicles going to electric to many of the newer cars being front-wheel drive, thus having to have an electrical fan. So, it is sort of off-the-shelf technology to put electrics even in rear-drive cars. Like I said originally, I think it is more or less a coin flip as to which takes more power, and I have to think the mechanical is more reliable.

ayalar007 · #15 10-21-2004, 04:53 PM

In the early 90s Ford started, and in some cases still is, using rear wheel drive cars with electric fans for example the Crown Vic and the Thunderbird (old version). These were big V8s running pretty hot if you asked me. When I lifted the hood on my mom's (then) brand new thunderbird, I saw what the guys at ford had done. IMHO it really is a waste of time to fiddle with electric fans.
Now back to the wonderful world of MB cars. My 300Sd has an electric fan pusher. If MB engineers would have thought that electric was better than mechanical, why didn't they just add ANOTHER fan as a puller. Yet they didn't. Somewhere in their engineering bible, they must know something we dont (maybe that's why they get paid the big bicks!!)

OhioSDL, you own an SDL, I dont have to tell you how careful you have to be with those aluminum heads. Imagine what would happen if all of a sudden your wonderful, low energy fan decided to die, and the temp started to climb.

I would be really worried if I were you!

I cant say for sure becasue i have not really paid attention to your application, but my fan has 2 redundant belts. So if one goes, I can still make it home and replace it if it came to that. But more than that, one can tell when the belts are worn and need replacing, and you replace them, you can't say the same for electric motors. Clutches, for the most part will last you a good 100,000 miles, and when they begin to go, you can tell by the temp being a slight higher than normal! You dont have that option with an electric.

Then again what do I know!

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