What are the differences between OM606 fan clutches? - PeachParts Mercedes-Benz Forum

KarTek · #1 07-01-2014, 09:27 PM

So, I need a new clutch for the fan and I was looking at them from various sources (PParts first, of course). I noticed there seems to be a break in the years for the part numbers - '95 to '97 and '98 to '99.

The later years are vastly more expensive than the earlier years but I can't imagine why that might be. They have to fit the same water pump configuration I would suspect. Just wondering why the difference.

Thanks for the insight.

jay_bob · #2 07-01-2014, 10:22 PM

95 to 97 are N/A engines
98-99 are turbo engines

Water pump is probably different

And yes you are right that clutch is $$$

vstech · #3 07-01-2014, 11:32 PM

Fan diameter, blade pitch and number of blades is larger on 97+
Larger blade air movement equals more friction to handle the load. Clutch needs to be beefier.

KarTek · #4 07-02-2014, 11:27 AM

OK, it makes sense about the fan being bigger. Guess I have to bite the bullet and buy it.

Thanks.

Zulfiqar · #5 07-02-2014, 12:27 PM

I am using a turbo fan clutch on my W124 E300D, works a treat. if you have about an hour time and about 10 dollars to spare, you can try to fill your old one, its not that hard. most probably it only needs about 5cc of silicone oil. my car originally uses a BEHR branded clutch which is useless, it acts like an on/off switch and mostly made the car sound like a garbage truck all day long in summer.

the newer model clutch actually behaves like a fan clutch and it also makes the fan blow a bit even at idle speed (better)

Olivier · #6 07-02-2014, 06:53 PM

Hi Kartek,

I use to run myne without fan and with the Rad blocked by cardboard.
It never over heated.
Just to say

Have you thought of refilling the fluid? As above/// Just read it before I type...

jay_bob · #7 07-02-2014, 07:01 PM

Quote:

Originally Posted by Zulfiqar

my car originally uses a BEHR branded clutch which is useless, it acts like an on/off switch and mostly made the car sound like a garbage truck all day long in summer.

I just replaced my fan and clutch with genuine MB and that is the best description for the sound I have heard yet - a garbage truck. I thought there is no way it is supposed to sound like that but I guess that's it.

jay_bob · #8 07-02-2014, 07:04 PM

Quote:

Originally Posted by Olivier

Hi Kartek,

I use to run myne without fan and with the Rad blocked by cardboard.
It never over heated.
Just to say

Have you thought of refilling the fluid? As above/// Just read it before I type...

No disrespect but the climate in Scotland and the southeast US are two different animals. Typical summer temperatures 85-105 deg F (or 30-40 C) from May to October.

From experience the lack of the engine driven fan causes the engine temperature to run almost 100 C instead of the usual 80 C. Also the air conditioner performance goes to zero because the condenser does not get enough air flow from just the electric fans.

KarTek · #9 07-02-2014, 08:49 PM

I may try to refill the clutch. I really wanted to have the car completely ready when I come to the event in SC next weekend. I also have to pull and re-fit the injection pump so I'm not sure what I'll be able to get done before the trip.

I may just leave it alone until the trip is over.

On a side note, Jay Bob, do you know about this, it's in your neck of the woods: First Anual Central Carolinas Get Together Extraviganza!!

Olivier · #10 07-03-2014, 06:57 AM

Quote:

Originally Posted by jay_bob

No disrespect but the climate in Scotland and the southeast US are two different animals. Typical summer temperatures 85-105 deg F (or 30-40 C) from May to October.

From experience the lack of the engine driven fan causes the engine temperature to run almost 100 C instead of the usual 80 C. Also the air conditioner performance goes to zero because the condenser does not get enough air flow from just the electric fans.

That was just an experiment. This was done trashing it and on 25 degrees... And in traffic town too... Just to see what temperatures it goes. It never over heated. The electric fans do kick in once a certain temperature is reach, aircon on or off it doesn't matter they will start.
I guess its a security build in

Without the fan the car should be more then fine, unless you are in the Sahara...

vstech · #11 07-03-2014, 07:02 AM

... It's possible, but the car, engine,ac, and YOU will function much better if the engine fan is working...

Zulfiqar · #12 07-03-2014, 10:08 AM

Quote:

Originally Posted by jay_bob

I just replaced my fan and clutch with genuine MB and that is the best description for the sound I have heard yet - a garbage truck. I thought there is no way it is supposed to sound like that but I guess that's it.

I fiddled with the original BEHR fan clutch so much that I got it to behave, It would smoothly lockup at about 100C engine temperature, roar for a few minutes and shut up. that way I was not running the fan all the time, above 3000 rpm the fan decouples anyway and it was a relief to not sound like a tank at red lights every single time.

But its still annoying to hear everytime you start from standstill in summer and it had poor air movement at idle speed - not the best design I think.

so I got a very good deal on a 99 turbo model fan clutch made by Horton, its a genuine MB part. It behaves like a fan clutch should - while testing I could feel it couple and decouple as the radiator temperature varied. This one sort of speeds up the fan at idle speed too - you can actually feel air flow at idle speed.

If yours is roaring all the time its bad - btw MB sedan engine fans will roar like no other car I have heard till now.

KarTek · #13 07-03-2014, 10:46 AM

Mine is uncoupled all the time. I'm looking to improve idle and low speed air conditioning performance. The aux fans need attention too. They kind of get locked up and I can literally spin them by hand like a propeller and they will start turning.

jay_bob · #14 07-03-2014, 11:06 AM

My fan is not roaring all the time, just when it's really hot outside.

It is most apparent when accelerating from a red light especially after coming off a highway run.

Once the temperature cools down the fan decouples again. It's Just Really Loud when it's running.

Zulfiqar · #15 07-03-2014, 11:08 AM

Before you do anything to the fan clutch - make sure your condenser and radiator fins are clean enough to pass air - because no air movement = no temperature change at clutch bimetal element => clutch wont work.

If everything is in order and still your fan thinks its a pinwheel then you need a bottle of 10,000 cst or about 7000 wt oil and a syringe to make it "respect your thoritay" - after extracting clutch from car and unbolting the fan wheel remove the bimetal plate by pushing it downwards on the clip end and slide it out, you might need to cut the silicone goo first.

heat up clutch in oven - remove and jam your syringe in there and push the 5cc of oil in it pack it up - seal with new goo and install. it should start working. If not then repeat the fill.

As a very rough start point, if you feel the fan very feebly engage at startup and does not drag with above idle rpm at all then about I have expereinced that about 5-6cc makes it work again. If its completely empty then you need to repeat the exercise.