cooling fan 240d versus 300
 

While I was trying to keep my 240 running I noticed that my 300dt has a visco clutch for the fan.The 240 is hard coupled.

Why did they do that and would it be possible and advantageous to get a visco clutch in the 240D?

I would think it would save some fuel, noise and gain a little power?

Please any of your thoughts or experiences.

Mercedes designed it that way, probably for a reason. That said, I don't see any way it could hut to change the fixed fan for a visco fan. It won't save much fuel or power to make up for the cost of converting it.

I'd check to make sure that the water pumps designed for clutches are the same as direct coupled water pumps. Their lengths could be different.

Water pumps are the same across all 123's, gas and diesel. I think the only exceptions are some obscure euro gasser models.

There are differences between the water pumps on the 616's and 617's in the vans, including changes in model years.

That may be true, but those are not 123's.

...what?

I have them both , so it won't take that much work to give it a shot.
Forced, I always heard that the cooling fan can taken up to 3 to 4 HP at higher RPM. If you see the size of blade and imagine it spinning at 3000RPM and add the losses at 3HP in the V-belt? At high speeds I would think that there is enough cooling from the air. The visco still takes some HP since there is drag. But even if it saves 2 to 3 HP that is a lot for 240D

I also hope that there will be less noise

The visco fan never turns higher than 3500rpm so there are no extra losses at high rpms.

However, fan-clutches do fail, something solid-fans almost never do.

Happy Motoring, Mark

The fan clutch on my 190D is dead so the fan never engages. The only time its ever a problem is if I'm stuck in traffic for long periods of time. I can cope by putting on the heat in the car. I should fix that someday but the electric fan clutch on the 190D is nearly $200...

Anyway I don't think there'll be a problem. You figure it out and if its an advantage I'll try it too ;)

Viscous fan clutch for a 617 in a van is $500.

I brought up the issue of vans because MB makes a viscous fan clutch for the 616 which they install in their vans. Don't know why they use direct drive in the cars with 616's but clutch's in the vans with 616's.

The only reason the 240 has a solid fan is cost. A visco fan will improve HP and fuel economy without hurting the engine. But.....a properly sized electric fan is better than either. That's what I did on my MB's and most other vehicles that I own.

I have been out of contact for a while, travel, hospital and other bad things.
Thanks for all the responses and suggestions.
I Think I will take the fan out and mount an electric of a 300D airco in front.
Nice flat motors.

Thanks again.

The solid fan has less blades though, so it probably doesn't cut off as much HP at higher RPMS as the more-blades fan would if it were coupled. At one point I was tempted to just throw a 240d fan on my car, but I managed to find a low miles plastic one. Also I couldn't get the fan off the 240D in the junk yard. :D ;)