I have a 871 recently inframed and the oil pump seems to be making a humming noise any suggestions on what it may be? I'm hoping it's only shims
probably wrong shim. some had a bad crank gear that had improper clearance in the teeth when it was made.
Ok thanks I'll look into re shimming the pump then
Check the backlash on the upper oil pump gear before you remove it. If the lash is ok then the noise is probably a worn shaft inside the pump. Let me know if you need specs.