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

SemperFiDawg

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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

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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.
 

racerone

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Have battery load tested.-----Inspect the battery cables.----Test with good booster cables direct to the starter.
 

jerryjerry05

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Should have done a compression test before removing the head.
Low comp on 1 or more cylinders can cause hard turning.
 

SemperFiDawg

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After sleeping on this I had moved my battery to the front of the boat and bought a cheap 8 gauge battery extension cable off Amazon to do so. I butt spliced the ends of the new cable to the old with a quality butt splice lug. The move extended the distance of the battery from the starter/ solenoid from 5 ft to approx 15 foot. I read yesterday that DC current if very sensitive to increased length of wire more so than AC. I'm wondering if the increased distance is accounting for the problem. I measured the volts at the starter at 12.4ish when the ignition switch is engaged but I didn't measure the amps. I'm gonna move the battery back closer to the starter and see if it makes any difference. I've decided to replace the cylinder head gasket while I have it off and I can move the battery while I wait for the gasket to arrive. I won't be able to test it until I have everything reassembled but it's just one more thing I thought of to rule out a possible cause. Again, if anyone has any more suggestions let me know. I'll update this as I troubleshoot.
 

racerone

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Had a fellow call me for a flywheel for his motor.----Had no spark.----I said " you don't need a flywheel "----He drove 4 hrs to bring me the boat / motor.-----He had installed new expensive parts.---Turns out the first new part he installed was bad.----Easy fix here.-----So yes even new parts can mislead a novice.
 

jerryjerry05

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(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 have experienced this in automobile engines, when changing the distributor, but never in an outboard. Put the gasket back on, use sillycone and let it set for a day then do the compression test.
 

The Force power

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(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 have experienced this in automobile engines, when changing the distributor, but never in an outboard. Put the gasket back on, use sillycone and let it set for a day then do the compression test.
On a 4-stroke when the valves timing is off, yeah maybe
On a 2-stroke?? I can only see this happening if the (intake reeds are seized solid/melted-on???) but then it would be in a scenario as your post #5
 

SemperFiDawg

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Most times these head gaskets can be reused
I actually considered it. Overall it looked real good but it had one spot on it about the size of a ball point pin head that looked like it was showing some corrosion with dimpling so I decided to just replace it while I had it off. I moved my new battery to within 6 feet of the starter and replaced the wires leading from the battery to the starter and ground with 2 gauge wire. Still waiting on the head gasket to come in the mail. If this doesn't fix the problem I'm out of solutions.
 

tphoyt

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I’m going to guess your new battery set up will fix your problem. And good call on waiting for the new head gasket. No point in doing it twice if you don’t have to.
Best
 
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