Visco Fan! - Page 2 - PeachParts Mercedes-Benz Forum

ancho · #16 08-24-2013, 12:21 PM

I like the relative failsafe simplicity of the viscous clutch fan. Electric fans, if I am not mistaken, came about with the advent of front-wheel drive cars with transversely mounted engines (thereby making a pulley-driven fan impractical). Lots of things to go wrong with an electric fan setup -- motors, relays, wiring, controller, switch/sensor, alternator -- a clutch fan provides simplicity and in my opinion, reliability.

Zulfiqar · #17 08-24-2013, 02:01 PM

yes thats why I love the visco fan on my E300D, simple working and gigantic.

OTOH my E320 W210 has an electric fan, its surely quiet as a mouse as its variable speed but both cars maintain the exact same engine temperature.

lsmalley · #18 08-24-2013, 02:25 PM

Quote:

Originally Posted by Zulfiqar

the fan blade wheel is not designed to spin up to high rpm, the visco clutch is there for 2 jobs,

one to freewheel when the clutch is cold and then to freewheel at high rpm even when the clutch is hot. You do not want it blowing apart at high rpm and take out the radiator etc.

So do not lock it. If you are on a budget proceed to a hobby store and get some RC diff fluid about 8000 wt and fill about 5 or 8 cc and test again.

I have never heard of this happening. Maybe if the bearing bracket came loose. But why would a fan break apart because it is spinning high speed? When some fan clutches fail some either free wheel or lock up. I'm sure that when they lock up, they are not in danger of suddenly breaking apart. I could be wrong, but that just sounds ridiculous for MB to even produce a part that would break away from the force of velocity. Can anyone verify that this is correct?

MBeige · #19 08-24-2013, 06:12 PM

Quote:

Originally Posted by lsmalley

I have never heard of this happening. Maybe if the bearing bracket came loose. But why would a fan break apart because it is spinning high speed? When some fan clutches fail some either free wheel or lock up. I'm sure that when they lock up, they are not in danger of suddenly breaking apart. I could be wrong, but that just sounds ridiculous for MB to even produce a part that would break away from the force of velocity. Can anyone verify that this is correct?

I've seen it many times in these discussion boards. Don't let it happen to you.

The one in my 300D was seized, so it was also overcooling the engine especially at speed. I do not drive the car much so I was not worried about putting too many miles on a seized clutch, but later on I replaced the clutch AND fan with brand new units because the fan showed signs of cracking.

The fans can break apart due to age, excess vibration, imbalance, etc.

lsmalley · #20 08-25-2013, 12:12 AM

Which way does the fan spin, CW or CCW? I think the one I had was spinning CW, but now the one I have spins CCW. Is that possible or does the crank/bearing bracket spin with the direction of the engine pulley? Also, when the clutch warms up and the fan locks, is it a solid lock where you can't even turn it with your hands or is it just more firmer? I noticed that the clutch seems to have more resistance after I put it in cold water, vs when I put it in boiling hot water?

oldsinner111 · #21 08-25-2013, 07:51 AM

looked at a lot of flex fans today the problem with my m104 is that it has 3 holes to bolt with.You'd need to write a manufactury and tell them to send a blank fan.And you drill it.

vince · #22 08-26-2013, 08:36 AM

The viscous clutch never "locks". When the bi-metal spring is exposed to the preset temperature it will bring the fan up to 3,500 rpm +/-, IIRC.

Zulfiqar · #23 08-26-2013, 08:53 AM

the term lock is used for understanding the function. It just engages the drive torque.

btw @lsmalley,

the fans do break off - they are made for a limited rpm which the engine itself can exceed and also take into consideration that the fan pulley spins overdrive from the crank pulley.

This sort of breakapart failure is mostly known to BMW fan clutches - the lockup when they fail and there goes your radiator/engine etc.

MB fan clutches usually start to freewheel - meaning they dont respond to temperature change due to no fluid inside it. But siezure is also a cause of such failure and is seen sometimes.

lsmalley · #24 08-26-2013, 07:46 PM

One thing is for sure....I am now an expert at removing my fan clutch and the only things I move out of the way is the distributor cap, fan shroud, and radiator bracket....done in 15 mins flat! On another note, I drained whatever was in the clutch. I didn't have any silicone, but what I did add was something I had called Bardahl's no smoke. Its a really thick oil about the same viscosity as what was in the clutch. Clutch no behaves like it is brand new. Cold engine: fan turns maybe 1/4 - 1/2 of turn. Ambient engine: fan turns a full turn +. Hot engine: fan turns 1/4 turn....And now I can hear the roar that everyone talks about.

Zulfiqar · #25 08-27-2013, 01:34 PM

the silicone fluid is used as it is not affected by temperature. The high CST is also used to ensure maximum drive torque is transferred.

Good 10,000 cst fluid should be about 10 dollars tops at an RC hobby store. the fan usually takes about 5 or 8cc to make it come back to life. petroleum oils wont work as good.

lsmalley · #26 09-21-2013, 11:52 PM

I just couldn't leave well enough alone. I decided to upgrade my w201 visco clutch and fan to the w124. The blades are a lot wider and seem to put out a ton more air than my previous fan. There was no modification or anything required, even though the w124 is slightly thicker, its a perfect fit. Removed old w201 clutch and fan and then installed new w124 clutch and fan.

benfield4 · #27 09-30-2013, 05:40 PM

Do you notice when the fan is locked up at speed? A few years ago I replaced the original visco clutch with a BEHR unit. The fan locked up and roared a lot more than the OE did. Cooled better but the downside was that with the AC on it robbed so much power away from my 103. My car is a W126 89 300SE and became a turd whenever the fan was locked up. I got so tired of hearing that fan drone away that I did the high amp alternator conversion with an electric cooling fan conversion. This last summer was my first with the conversion and the car ran cooler in 90F + ambient temp traffic than it ever ran with either visco clutch fan. That is sitting idling in traffic with the AC on in summer heat. It did rarely creep up to 100C the aux fan kicked on an it went back down quickly. I am happy with it and even though it was more than I wanted to spend it works well and does not rob power away. I saw no change in my gas mileage as it still gets around 19 - 20MPG.

compu_85 · #28 09-30-2013, 05:55 PM

What fan did you use and how did you trigger it?

lsmalley · #29 09-30-2013, 07:29 PM

I need the forum's input on manual engine cooling

benfield4 · #30 09-30-2013, 07:29 PM

I used:

Spal 30101516 16" Straight Blade Low Profile Fan
Spal 30130074 16" Fan Shroud Gasket

I used an automotive relay that turns the fan on and off wired to a switch in the cabin. The relay is a bosch and came from a ford's aux fan wiring in the fuse box. Its manual control right now but its easy to trigger. I can leave it on all the time in the summer or turn it on and off as I like. when the temp is in the 50's or below I don't even need to run the fan. I usually turn it on if I am stuck in traffic to get some airflow over the engine. The fan is a little noisy if your outside standing next to the car while its running. Inside you can't really hear it.