Mercruiser 7.4 Starter Grinding/Partial Engagement?

[salvageyard saviour]

I don't think so, but is it possible the flywheel could come loose from the motor?

I actually just took a video of the engine cranking over with plugs out, cranks fine but it does make a weird noise.

Any ideas what's causing that noise?

Not likely the flywheel could come loose. To be honest, I've personally never had a ring gear break off either.

Read about it a couple times on a hot rod forum, they were also discussing big block Chevys.

Hard to tell, but that doesn't really sound starter pinion teeth grinding. They have more of a clanking ringing sound.

 

[CLi87]

Not likely the flywheel could come loose. To be honest, I've personally never had a ring gear break off either.

Read about it a couple times on a hot rod forum, they were also discussing big block Chevys.

Hard to tell, but that doesn't really sound starter pinion teeth grinding. They have more of a clanking ringing sound.

That's with the plugs out, if I put the plugs back in it will just start grinding and won't turn over at all.

 

[nola mike]

That's with the plugs out, if I put the plugs back in it will just start grinding and won't turn over at all.

You might still get some info from getting a voltage drop with the plugs out

 

[SternDriveEd]

I’d be interested in the battery voltage during cranking. In other words let’s say the battery voltage is 12.5 before cranking the engine over. It should be at least 10 volts during cranking. If it drops below that, possibly a battery issue here. Especially since the starter only turns the engine over with the spark plugs removed. I’m thinking a battery issue is the root cause.

 

[Tail_Gunner]

Ayuh,..... Those are both pmm starters,....
Are ya usin' bolts that came with the starters, or the bolts that were in the motor,..??

These new style starters use a slightly shorter bolt, by 'bout a 1/4" or so,.....

Shimmin' a chevy starter, moves it away from the flywheel, not closer,.....

Pay attention to that post, what it model is this 454? Is it a Mark 4 block?

 

[CLi87]

Update...finally got time to pull the motor and found the problem, starter was not fully seated because apparently someone before me had stripped out one of the starter bolt holes and put in a helicoil repair that had failed causing the starter to not be stabilized and grind against the ring gear. Unfortunately this was very hard to see when the engine was still in the boat but quite obvious after I pulled the motor. The old ring gear wasn't too bad but had some grinding on the teeth because of the starter so I went ahead and replaced that anyway. I got most of the old helicoil out but there's a tiny bit still stuck at the top I can't get out, what would you guys recommend? Drill it out some more or just leave it and install the new helicoil?

 

[Scott Danforth]

I would try the helicoil, however you may have to drill out for a timesert

 

[todhunter]

I would go straight for a Time-Sert. I hate Helicoils.

 

[CLi87]

Well the helicoil kinda worked, put a new one in and it was tightening...until it wasn't, I felt it break loose slightly but it's tight enough where there's no play on the starter. I tried turning the starter over with a power probe but it just thunks from the Bendix trying to engage but the engine doesn't turn over. I was looking at the clearances and took some pictures to see what you guys think, are these clearances normal? Seems either the flywheel is sticking out a bit more than normal based on the starter? The flywheel seems to stick out past the end of the starter by a bit?

 

[Scott Danforth]

Well the helicoil kinda worked, put a new one in and it was tightening...until it wasn't, I felt it break loose slightly but it's tight enough

It's stripped. It will never hold. Time for a timesert

 

[CLi87]

It's stripped. It will never hold. Time for a timesert

Yea I'm gonna pull it again and replace with a timesert, but for the time being I was trying to see if the starter would turn the engine over correctly, how do the clearances look to you? Does the flywheel seem off or is it normal to have a gap that size between the flywheel and the block?

 

[bwgintegra]

Yea I'm gonna pull it again and replace with a timesert, but for the time being I was trying to see if the starter would turn the engine over correctly, how do the clearances look to you? Does the flywheel seem off or is it normal to have a gap that size between the flywheel and the block?

Did you ever get this resolved? Would like to hear how things turned out. Is the starter bolt hole washed out where the knurled part of the bolt makes contact inside the block?

 

[CLi87]

Did you ever get this resolved? Would like to hear how things turned out. Is the starter bolt hole washed out where the knurled part of the bolt makes contact inside the block?

I ended up drilling the hole out larger and tapping it and then putting an E-Z Lok threaded insert in.