Crankshaft pulley screw broke off

When operating a car, an unpleasant breakdown may occur - a broken generator pulley screw, which is attached to the crankshaft of the car engine.
The main reason for this malfunction is a poor-quality screw, or its tightening when installing the pulley.

You can repair this problem yourself. This will require some effort. In rare cases, it is possible to turn a crimp by hitting a small chisel with a hammer. Most often it is necessary to drill along the axis of the broken screw. Let's look at repairs using the example of a VAZ engine.

Tools and materials

To dismantle the broken generator pulley screw, we will need some tools:

• electric or hand drill (wrench);
  
• metal drills with a diameter of 3-5-7 mm;
  
• conical extractor with left-hand thread;
  
• core;
  
• flat screwdriver;
  
• liquid for removing rust and scale (WD-40).

Repair stages

It is necessary to inspect the end part of the break, remove the burrs with a screwdriver and treat the circumference of the broken screw with a special liquid for removing rust and scale (WD-40). This will make it easier to remove the screw shaft later.
Let's determine the approximate drilling depth by comparing the broken part (head) of the screw with the new screw. As a rule, it does not exceed 1.5 cm.

Next, we determine the condition of the end of the crease. It is desirable to have a flat surface perpendicular to the axis of the screw. If the surface is inclined, you need to select the appropriate drill and work with it a little. This will make the surface level and make drilling easier.

We mark the drilling point of the broken screw. Using a hardened, durable metal drill with a diameter of 3 mm (preferably domestically produced), we begin to drill out the broken screw to its entire depth.

In some cases, such drilling is sufficient. All that remains is to change the drill to a conical extractor with a left-hand thread, screw it into the hole and unscrew the remaining screws.


If the broken screw cannot be removed, it is necessary to repeat its drilling with a drill of a larger diameter. Such drilling greatly weakens the crease, and at a certain stage its removal is not difficult. Its thin walls can simply be destroyed without harming the threads in the crankshaft. After removing the crease, it is necessary to carefully remove all remaining metal from the crankshaft.

conclusions

A small number of tools and skills in working with them made it possible to carry out a rather complex type of repair - breaking off the screw connecting the generator pulley to the crankshaft.

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