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Anyone who has had the opportunity to examine the water pump of a Maserati Mexico, 4-Porte I, Ghibli, lndy or Khamsin will come to this conclusion. What were they thinking? The pump shaft rotates via a flexible cable that is attached to the air conditioning compressor clutch pulley. The housing of the water pump actually provides the mounting for the AC compressor. I must believe that there was a valid and logical reason for this type of a drive attachment, but I have yet to think of it. Maybe one of you knows the engineering theory behind such an eccentric design.
Almost anyone who has owned any of the aforementioned Maseratis has probably snapped a water pump drive cable. Fortunately an emergency backup drive was engineered into the system. The noisy back up drive will get you home or to the garage, while "ticking" like a stuck valve.
Let me explain and get to the point of this article. Several owners and mechanics have questioned me about the method of attaching the drive cable to the water pump shaft. Done incorrectly it can be a frustrating, time consuming, and may leave you with a noisy water pump drive, or worse, leave you overheated and stranded.
You should not do this on the car. The pump and the AC compressor assembly should be removed from the car and this entire process should be done on the bench.
When replacing the water pump drive cable, you must assure that it is connected to the water pump shaft at the correct angle, on the correct side of the arm, and be
mounted to the shaft so that it does not swivel or pivot. Photograph #1 shows the correct mounting position of the cable. Note that it is mounted to the water pump side of the drive arm.
The original connection is a heavy rivet, which firmly holds the cable in place. I would suggest using the same method of attachment when replacing the cable. If you opt to use a nut & bolt, you will find that there is little or no available clearance, and it may interfere with the grease zerk fitting on the water pump. It is also unlikely that you will be able to get such a small fastener tight enough to prevent loosening after some mileage. The illustration (left) shows the angles that were measured from the above factory new shaft assembly.
Photo #2 shows the emergency drive shoulder bolt and the cable spacer. The cable spacer goes between the outer end of the cable and the clutch pulley. The spacer will prop the cable up so that the cable is the same distance from the pulley at both ends. The shoulder bolt is fitted to the pulley so that the end hole of the shaft arm is over it.
Photo #3 shows how the shaft is connected to the clutch pulley. The cable should be bending as shown, and the shoulder bolt should be resting up against the ID of the end hole.
Photo #4 shows the rotation of the pulley. The bend in the cable (which can only occur if the cable is attached to the shaft so that it can not pivot) provides tension, which acts as a shock absorber when accelerating and decelerating. Once in motion, the backup drive shoulder bolt will have a tendency to float in the middle of the open hole, only making light contact with the edges. This eliminates the metallic ticking that would otherwise be present if the cable were allowed to freely pivot at the connection to the shaft.
Once you are ready to secure the AC compressor to the water pump body, make sure you have your AC belts over the pulley before mating everything together. It is vital that the AC compressor be aligned as precisely as possible with the water pump. As the clutch rotates, you must have an equal amount of tension on the cable throughout the complete rotation.
If the compressor is not aligned just right, then there is a tendency for the cable to be too taunt at one extreme and too slack at the other extreme of the rotation. This would cause a rapid and forceful tugging that could quickly break the cable. You can fine-tune the position of the AC compressor by using various thickness washers at each of the four bolts that connect the compressor to the water pump housing. Once you have completed the mating of the water pump and the AC compressor assembly, you should be ready to install the complete assembly.
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