What would make a flywheel hard to spin? Starter won't spin it.

SemperFiDawg

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Joined
Oct 15, 2024
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2
Recently purchased a 1998 Force 120 hp as part of a package deal. Did NOT test it before purchase as the boat alone was worth the asking price, but seller assured me the motor had no issues.
Upon attempting to crank it the first time the starter would engage the flywheel but not spin it. Battery was brand new 800 CCA. Tested the voltage at starter with ignition engaged and had over 12 volts. Pulled starter and took it to local shop. Upon his inspection he found (and I observed) the shaft of the starter had a wobble in it when engaged and mechanic stated that it was warped. We both surmised this would account for the starter engaging but then becoming "bound" in flywheel preventing it from turning freely. Ordered new starter. Put it on boat today. It will engage flywheel but not turn it. If I pull the plugs it will turn the flywheel. With plugs in I can put a 15/16 socket and a 1/2 wrench on it and turn the flywheel but it's not easy. I'm not sure exactly how hard/easy it should be so that really tells me nothing except the engine isn't seized up. . When I turn it with the wrench I can hear "compression sounds". I'm at a loss. I called the starter guy just to pick his brain and speaking of my old starter he said he had seen bent starter shafts on some old Briggs and Stratton engines where the flywheel shaft would warp due to internal engine damage and it would warp the starter shaft. We both thought that was probably not possible with an outboard. He said his best guess would be the cylinder timing was off and was creating high compression pressure preventing the engine from turning over. I'm at a loss and thought I may run it by this forum prior to taking it to a marine mechanic. Any help would be much appreciated.
 

SemperFiDawg

Recruit
Joined
Oct 15, 2024
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2
I pulled the lower unit just to rule that out. It still won't spin the flywheel with the lower off. Also pulled the head gasket. No scoring, pitting, rust. Nothing out of the ordinary. Still hoping someone can lob some suggestions.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
49,179
Clean all the battery cable connections from the battery to the starter
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
37,587
Have battery load tested.-----Inspect the battery cables.----Test with good booster cables direct to the starter.
 
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