View Full Version : Chipped flywheel. Why?

10-28-2004, 09:10 AM
I have some missing or chipped teeth on my flywheel ring gear. I plan on replacing it this winter, but my biggest question is why did it happen? I'd hate to fix it, just to have it happen again. It's a V-Drive, so it's pretty involved to fix it.
The motor is a '99 Indmar Chevy, MPI. Only 200 hours.
What causes this? I'm thinking the started needed to be shimmed, but could it be anything else?

10-28-2004, 09:20 AM
The starter was my guess also.

10-28-2004, 09:51 AM
Starter not disengaging or kicking in while the engine is running. That is why the starter gear is brass, but if the flywheel was brittle it could break off a tooth. Typically you can start the engine by moving the flywheel a bit clockwise, but with a v-drive that would be tough. You might want to have some things done while the tranny work is being done....

Jimn what should he look out for?

10-28-2004, 10:21 AM
I would say it could be any of the following, plus some:

Misalligned Starter (as said above)
Defective/Damaged Starter Gear
Defective/Damaged Starter Bendix
Foreign Material in the bellhousing
Loose Flexplate Bolts
Trying to start the engine when it is already running
Letting the starter kick out and back in in one start sequence without letting the engine stop rotating (operator error, intermittent ingition problem)

10-28-2004, 10:24 AM
It will still start, but if the motor comes to rest at the spot where the bad teeth are, it "clunks" really hard and only moves the engine a little bit. You have to turn the key several times (and several clunks) before it catches.

10-28-2004, 10:28 AM
Does it always clunk, or just when it is in a bad spot, do you know, or are you just assuming that when it clunks it is in a bad spot. It could be a bad soleniod too. But it sounds like a missaligned (or loose, have you checked for missing starter bolts) starter.

10-28-2004, 11:01 AM
Originally, I thought it was a bad starter, and replaced it. This fixed the problem temporarily...... until the bad flywheel chewed up the bendix on my new starter....
I'm assuming it only clunks when it stops at the bad spot. Even when it starts on a good spot, you can hear the "chink, chink, chink" as the bendix passes over the bad spot while the engine is turning over.

10-28-2004, 11:09 AM
Now the question that begs to be asked is, if it isn't the starter, why would this "fix it temporarily". My guess it was the starter but the damage had already been done to the flexpate teeth. I am sure there are other answers though...

10-28-2004, 11:14 AM
My thought was..... it fixed it temporarily because of the brand new teeth on the starter bendix. They allowed just enough bite to turn the flywheel. But each time it hit the bad spot, it wore the teeth more and more, until it got to the same point as before.

10-28-2004, 11:27 AM
You are absolutely correct if you put a new starter in with a new bendix into a motor with a bad flywheel it will work fine until the bad flywheel destroys the teeth on the bendix. If there is ever a bad flywheel you need to replace it the same time you replace the starter bendix. You should be able to get a new starter bendix without buying a whole new starter. However I would not do that, because the starter clutch may be damaged. You may want to take your starter to a rebuild shop and ask them if they can put a new clutch and bendix in it.

10-28-2004, 11:29 AM
Let's just call it a flywheel. If the starter hasn't been serviced every year (as it should be), the Bendix shaft and gear are probably rusted and the gear can't move freely enough to get out of the way when the motor starts. I have also never seen a brass Bendix gear. A steel or iron ring gear would chew up a brass gear really fast. Usually the Bendix is "Triple Plated" with cadmium and that gives it a brass coloring. It's possible that the starter needs to be shimmed, but I haven't seen many on boats that had a problem with this. I have seen a couple that had stuck Bendix gears and after sitting all winter with the gears in contact, the ring gear had rusted enough that those teeth were weakend and broke off. You're replacing only the ring gear, right? If the bilge was flooded and the water sat for a long time (like over the winter), you'll see a rust line across the flywheel and I would guess that the broken teeth are very close to this area.

What tranny work is being done?

10-28-2004, 12:36 PM
I was wondering the same thing.......

lakes Rick
10-28-2004, 02:43 PM
Good possibility that AFTER you replace BOTH, the starter drive and the Ring Gear, you need to have a mechanic look into shimming your starter.. Very common on Chev V8's.....

10-28-2004, 03:53 PM
It's common on Chevy V8's, but I have never seen one in the time I worked on boats that came in with a shim. I had to add one once, but that's all.

east tx skier
10-28-2004, 04:06 PM
Jim, could you briefly summarize what needs to be done to "service" the starter.

10-28-2004, 04:22 PM
what motor is it?
Old big blocks needed another bracket at the tail end of the starter to keep it from torquing away from the flywheel as it got worn. Mechanics know about that fix and it's a $2 item if that's what you need. There's even a tapped hole already in the block for mounting. Hope that helps

10-28-2004, 04:29 PM
It's a '99. The indmar 325hp Multi port injection.

10-28-2004, 07:59 PM
Disconnect the battery (-) cable and remove the wires from the starter. Remove the starter and inspect it for damage and rust. Rotate the gear so it climbs the shaft and lube the shaft with light grease. Let it return to its normal position and move it up a couple of times. Grease the gear, reinstall it and reconnect all cables and wires.

10-29-2004, 11:49 AM
Did anyone else on here know they needed to service their starter? I've never done this, so thanks Jim for the info.

BTW, a co-worker told me about someone who had to have the starter replaced on his Cadillac Northstar engine (car). Apparently the starter is internal and it cost $1500 to replace it.

east tx skier
10-29-2004, 12:50 PM
I've heard Jim talk about it for a while, but doubt it's been included in my dealer's winterization package. Since I'm doing it this year, I figure I'll have to know how to do this. Thanks, Jim!

10-29-2004, 03:31 PM
Servicing the starter is listed in the owner's manual under the 100 hour/annual service steps. It has also been discussed on the old forum.

$1500 is way high for replacing the starter. After removing the harness from the top end, linkage and fuel lines, the intake manifold comes off with 8 bolts, max. Once that's gone, the starter is right there. Admittedly, on the car, it's way back at the rear, but it's still only a couple of bolts and wires to remove it.