Here's a breakdown of methods, from least to most destructive:
1. Penetrating Oil and Patience:
* Apply liberally: Saturate the interface between the water pump and the fan clutch with a good penetrating oil (like PB Blaster, Kroil, or Liquid Wrench). Let it soak for *hours*, even overnight. Re-apply several times.
* Gentle persuasion: Try using a sturdy pair of channel-lock pliers or a large adjustable wrench on the fan clutch nut (if it has one; some are press-fit). Apply pressure *slowly* and *gradually*, working it back and forth. Avoid sudden jolts or excessive force, which could damage the pump or clutch.
* Heat (carefully): If the penetrating oil isn't working, you can try carefully applying heat to the area with a propane torch or heat gun. *Be extremely cautious* not to overheat the aluminum water pump, as it can warp or crack. Heat the area *around* the joint, not directly on the pump itself. Apply penetrating oil *while* the area is warm.
2. Puller Tools:
* Gear Puller: A small gear puller (the kind with three arms that you screw down) might be helpful if there's enough room to get the arms around the fan clutch. Position the puller's arms firmly and carefully tighten.
* Slide Hammer Puller: If a gear puller doesn't work, a slide hammer puller is a more powerful option. However, you need to be very careful not to damage the water pump or clutch. This requires the correct attachments for the puller.
3. Destructive Methods (Last Resort):
* Cutting: If all else fails, you might have to resort to cutting the fan clutch off. This is the last resort and will require a cutting tool such as a rotary tool (Dremel) with a cutting wheel or a reciprocating saw with a metal-cutting blade. Extreme care is needed to avoid damaging the water pump. Expect to need to replace the fan clutch after using this method.
Important Considerations:
* Safety: Wear safety glasses and gloves throughout this process. These parts can be surprisingly stubborn, and you could injure yourself if you're not careful.
* Proper Tools: Using the right tools is crucial. Improper tools can easily damage the parts.
* Replacement Parts: Be prepared to replace the fan clutch (almost certainly) and possibly the water pump if it's damaged during separation.
If you're uncomfortable working on this yourself, it's best to take it to a mechanic. They have the specialized tools and experience to safely separate the components without causing further damage. The cost of a repair is often less than the cost of replacing damaged parts due to improper separation.
