Starter: screeching sound

[vupilot]

I have a 1975 mercury 402 40hp that is new to me and was nicely restored. New wiring, hoses etc and fresh paint.

The 3rd day out the starter began making a screeching sound at startup. It sounds like a car that has slipping belts at startup if you have heard that before.

The sound occurs randomly but only when the starter is keyed to engage. Sometimes it screeches right when the key is turned and sometimes at the end of the start and sometimes but rarely now, not at all. It does not occur when pull started.

Im running dual purpose 850 amp battery for starting.

Thanks for the help.

[Dave1027]

Probably a bad bearing in the starter.

[hotrod53]

My 500 Thunderbolt is just starting that as well, I think I will pull it over the winter. I'm guessing bushings rather than roller bearings..right?

The previous owner reported premature disengagement of the starter, I cleaned and lubed the shaft and it has been fine. I'll bet that I'm losing RPMs because of a dry bushing.

[Chris1956]

Starters have bushings, and lousy ones at that. Put a bit of grease into each of them, and see if it goes away. The bottom bushing is under the brushes which make it a PIA to grease. See if you can move the bendix up the armature and put some oil on the top bushing. That might fix it, at least for a while.

[vupilot]

Thanks, All sound like good suggestions. I think i will also replace my starter this winter. I hope its not a PIA to do myself.

I also was getting that pre-mature disengagement. If I crank it more than about 3 seconds its disengages. Sounds like the theory of extra drag on due to worn bushings is quite possible. I will lube and see if that is a temporary fix for the rest of the season.