drilling and tapping a crank

[SledHed89]

1986 mercruiser
3.0l 4cyl IL

so the keyway is a bit messed up on the crank where the damper pulley is pressed on. the damper has some play in the crankshaft so i was thinking of drilling and tapping the crank and bolting the damper on to hopefully solve this problem. what do you guys think

 

[smokeonthewater]

Re: drilling and tapping a crank

never in a million years..... get another crank.... it needs to be absolutely true and needs to be a tight fit to seal.

 

[JustJason]

Re: drilling and tapping a crank

The million dollar question is why is yours messed up?

 

[SledHed89]

Re: drilling and tapping a crank

i just rebuilt the motor and my buddy told me he could polish the journals on his lathe. he put it in wrong and the mount dug into the end of the crank. the motor runs beautifully but the damper moves without the crankshaft moving. i would say about 1/8 inch, but it isnt leaking oil.

 

[wire2]

Re: drilling and tapping a crank

I'd be taking the crank and dampener to a machine shop, have them mill the crank keyway .020 or .030 wider, then broach the dampener to match, and make a custom key to fit tightly. Be careful to keep the same orientation.

 

[DianneB]

Re: drilling and tapping a crank

Definitely a job for the professionals!

Compare the cost of a replacement crank with the cost of having a PROFESSIONAL machine shop do the repair.