Starter starts something spinning in the back of engine only, nothing in the front.

[craig newton]

84 Mercruiser 5.7L, 260 sterndrive, alpha one gen one. Last time out was beginning of March with no issues, ran fine. Expecting the grandkids in a few weeks so I filled up a large tote with water today, lowered the out-drive and went to start it to be sure it was still running fine. The starter sounded like it was engaging as normal for a second then it sounded like it was just spinning. I could only see the front of the engine (alternator, water pump...) so I turned around and tried a second time to start it. Nothing on the front pulleys even budged but it started something in the back of the engine spinning. It continued spinning until I turned the batteries off. Anyone know what might have happened?

 

[Scott Danforth]

sounds like either your crank is busted or your flywheel studs are broke.

either way, the motor is coming out and you have to investigate

 

[racerone]

Take the starter out and inspect the solenoid and the starter.

 

[ScottinAZ]

Take the starter out and inspect the solenoid and the starter.

exactly. check the simple stuff first before pulling engine out. Wouldnt be the first starter that failed and the bendix gear failed to extend, or partially extend making one hell of a racket at the back of the motor

 

[Lou C]

Hopefully you can get at those starter bolts at the bottom rear starboard side. Can be really tough on some boats. On mine I pull out the rear seat on that side & remove the battery. Then it’s do-able.
If you replace get a nice modern PMGR starter (I like ARCO) & get their bolt kit. They must be the correct length do not use the old bolts. Bolts that are too long will allow the starter to twist & break starter bolts off in the block.
The modern PMGR starters spin the engine faster & draw less current as well. Also are much lighter nice when you’re holding it up with one hand & trying to get the bolts started with the other hand. That was a real trial with the old direct drive Delco starters.

 

[tank1949]

Pull starter and see if flywheel ring gear or starter teeth are in good shape. Hopefully just a bad starter set of teeth.

 

[nola mike]

So turning key off didn't stop whatever was happening?

 

[craig newton]

Hopefully you can get at those starter bolts at the bottom rear starboard side. Can be really tough on some boats. On mine I pull out the rear seat on that side & remove the battery. Then it’s do-able.
If you replace get a nice modern PMGR starter (I like ARCO) & get their bolt kit. They must be the correct length do not use the old bolts. Bolts that are too long will allow the starter to twist & break starter bolts off in the block.
The modern PMGR starters spin the engine faster & draw less current as well. Also are much lighter nice when you’re holding it up with one hand & trying to get the bolts started with the other hand. That was a real trial with the old direct drive Delco starters.

Hey Lou C: I appreciate you responding. Those two bolts have taken up almost two days of my time and so far I've removed one. Had to grind down a 14mm box end to fit between the bolt and the fly wheel cover. Fortunately, I'm retired. I'm going to take your advice regarding which starter to purchase. I'm familiar with ARCO but have no idea what PMGR stands for. Enlighten me please so I can be sure to get the right one.
Thank you.

 

[ScottinAZ]

PMGR is permanent magnet gear reduction

 

[craig newton]

So turning key off didn't stop whatever was happening?

That's correct but prior to that, the entire ignition was turning in the console as I turned the key. I imagine something broke off internally. My next project.
Thank you nola mike.

 

[craig newton]

PMGR is permanent magnet gear reduction

appreciate that info.