Removing a broken pilot bearing requires patience and potentially a few different techniques, depending on how severely it's damaged and how tightly it's seized in the crankshaft. Here's a breakdown of common methods:
Methods for Removing a Broken Pilot Bearing
The key is to break the bearing's grip on the crankshaft bore. Here are several ways to do it, starting with the least destructive:
1. Grease/Hydraulic Method
This method uses hydraulic pressure to force the bearing out.
- Pack the Pilot Bearing: Completely fill the center of the pilot bearing with heavy grease.
- Find a Punch (or Dowel Rod): Select a punch or dowel rod that fits snugly into the pilot bearing's center.
- Hammer Time: Insert the punch and strike it firmly with a hammer. The grease will act as a hydraulic fluid, pushing against the back of the bearing.
- Repeat: Repeat the process, adding more grease as needed, until the bearing begins to move.
2. The "Blind Hole Puller" Method
This is a specialized tool designed for this specific purpose.
- Insert the Puller: A blind hole puller expands inside the pilot bearing, providing a grip.
- Pull: A slide hammer or threaded rod is then used to pull the bearing out.
- Benefits: This method is often effective and relatively non-destructive.
3. The "Bread Method" (Similar to Grease Method)
If grease isn't available, bread can be used.
- Pack with Bread: Crumble white bread into the pilot bearing cavity until it's completely full.
- Use a Punch: As with the grease method, use a punch and hammer to compress the bread.
- Explanation: The bread, like the grease, will create hydraulic pressure to force the bearing out.
4. Chisel Method
This method involves carefully breaking the bearing shell. Use extreme caution with this method to avoid damaging the crankshaft!
- Use a Sharp Chisel: Use a sharp, flat chisel. A dull chisel will simply mushroom the bearing material.
- Carefully Strike: Firmly strike the bushing or bearing shell at an angle. Aim to cut through the bearing material, not just deform it.
- Create a Crack: If you've cut deeply enough, the bushing or bearing shell will crack, relieving the press-fit in the crankshaft bore.
- Remove the Bearing: Then, you should be able to remove the pilot bushing or bearing with your hands or pliers.
5. Welding Method (For Extreme Cases)
This is a more advanced method and should be done by someone with welding experience.
- Weld a Bead: Carefully weld a bead around the inside of the pilot bearing. Avoid welding to the crankshaft itself!
- Shrinkage: As the weld cools, it will shrink the bearing, loosening its grip on the crankshaft bore.
- Remove: Tap the bearing out with a punch.
Important Considerations:
- Safety: Always wear safety glasses when working on mechanical components.
- Crankshaft Damage: Be extremely careful not to damage the crankshaft bore. Any damage here can cause serious problems.
- Penetrating Oil: Apply penetrating oil around the bearing before attempting removal to help loosen it.
- Heat: Applying heat (e.g., with a heat gun) to the crankshaft around the bearing can sometimes help to expand the metal and loosen the bearing. Use caution and avoid overheating.
Removing a broken pilot bearing can be challenging, but with the right tools and techniques, it's a manageable task. Choose the method that best suits your situation and skill level, and always prioritize safety and crankshaft integrity.
