Diesel Fan clutch vs. Gas fan clutch - PeachParts Mercedes-Benz Forum

sptt · #1 09-10-2011, 12:01 AM

Would a w124 diesel fan clutch work differently from a w124 gas fan clutch? Are there different operating temperatures for the clutch to engage, disengage?

Billybob · #2 09-10-2011, 12:07 AM

Quote:

Originally Posted by sptt

Would a w124 diesel fan clutch work differently from a w124 gas fan clutch? Are there different operating temperatures for the clutch to engage, disengage?

The fans and the clutches rotate in opposite directions between the OM60X engines and the M103 cars for sure.

From a thread from a couple years ago:

Quote:

Originally Posted by Billybob

Does the arrow indicating rotation on the 103 clutch correspond to the actual rotation of 603 pulley? Seems to me that the 103 fan rotates counter clockwise and the 603/2/1 engines have their fan's pulley rotating in a clockwise direction. As the viscous clutch is designed to use rotational force to move it's fluid therebye effecting actuation I wonder if that difference matter's?

sptt · #3 09-10-2011, 12:40 AM

Wow...I also have found that when I do a search for a fan clutch on a Diesel 300D vs. a gasser 300E, different model #s show up for each! Maybe I can recoup some $$$ from having to replace my engine that burned up???

sptt · #4 09-10-2011, 01:08 AM

Billybob...I just checked the repair manual for both and notice that the fan blades for the Diesel and Gas are angled in opposite directions! Now everything makes sense! No wonder it wasn't engaging when it got hot. Found this on the internet:

Fan Clutch Rotation

Often, as a counter person, it will be necessary to ask the customer which direction
the fan clutch rotates. In response, more times than not, the expression of the
customer can be compared to a “deer in headlights”.
To assist the customer, a counter person should suggest the only

safe method of
determining fan rotation. With the engine off, direction can easily be found by looking
at the water pump pulley and belt.

•

If the pulley uses a V-belt, direction will always be clockwise.

•

If the pulley is poly-grooved and in contact with the grooved side of the serpentine
belt, direction will be clockwise.

•

If the pulley is flat and in contact with the backside of the serpentine belt, direction
will be counterclockwise.
If the wrong direction fan clutch is installed, the engine will overheat from the lack of
airflow across the radiator. Also, the clutch may break apart from operating in the

wrong direction causing damage to the fan blade, radiator and hood
(not sure if rotational direction on the fan clutch matters or not but why would they show different part numbers and look identical on the outside?)

Billybob · #5 09-10-2011, 02:54 AM

Quote:

Originally Posted by sptt

Billybob...I just checked the repair manual for both and notice that the fan blades for the Diesel and Gas are angled in opposite directions! Now everything makes sense! No wonder it wasn't engaging when it got hot. Found this on the internet:

Fan Clutch Rotation

Often, as a counter person, it will be necessary to ask the customer which direction
the fan clutch rotates. In response, more times than not, the expression of the
customer can be compared to a “deer in headlights”.
To assist the customer, a counter person should suggest the only

safe method of
determining fan rotation. With the engine off, direction can easily be found by looking
at the water pump pulley and belt.

•

If the pulley uses a V-belt, direction will always be clockwise.

•

If the pulley is poly-grooved and in contact with the grooved side of the serpentine
belt, direction will be clockwise.

•

If the pulley is flat and in contact with the backside of the serpentine belt, direction
will be counterclockwise.
If the wrong direction fan clutch is installed, the engine will overheat from the lack of
airflow across the radiator. Also, the clutch may break apart from operating in the

wrong direction causing damage to the fan blade, radiator and hood
(not sure if rotational direction on the fan clutch matters or not but why would they show different part numbers and look identical on the outside?)

I suspect even though the viscous clutch's housings are externally very similar ( the OM 60X fan is interchangable with an M103 and visa-versa) they have need for the same thermal operator and the need for the coolong ribs, the interior guts are different. If you look through the FSMs in some of them in the sections that deal with the clutch there are diagrams of the internal structure which a part of is a sort of series of spiral grooves radiating from near the center extending outward. The grooves are not straight lines but sort of elongated S shapes, but they do all go in one direction. As I questioned in the earlier post perhaps because of the different rotations it may be that the internal grooves are oriented differently and that mmight effect the operation.

If you look at the pictures available on the FASTLANE catalog you can see that the clutches both have the direction of rotation marked by an arrows on the label plate at the thermal operator.

I've got a number of OM 60X engines but I'd rather not experiment with a clutch that is designed to rotate in the opposite direction than the water pump turns.

If you're looking for a replacement clutch one spec'd for a 98/99 E300 is better in that it is designed to cycle on at a lower temp and the newer plastic 11 blade fan fits it. That clutch is usually significantly less expensive than one spec'd for the early years. Cheaper, lower temp activation, and a higher efficiancy fan that may do less damage to the radiator if it ever contacted it, don't know how you can beat that!

sptt · #6 09-10-2011, 08:10 AM

Thanks for the info! I'll check into it and see what I can find.

sixto · #7 09-10-2011, 12:03 PM

The 606 turbo and 11 blade fan setup sits further aft than the standard 87 300D setup. You might have to trim the turbo air intake hose for clearance -

Sixto
87 300D