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!