Bendix gear slipping, something serious or is this normal?

CaneCutter79

Chief Petty Officer
Joined
May 24, 2009
Messages
454
I was de-greasing the motor with some "Gunk" degreasing foam around the block and seals yesterday. Before degreasing, I started the motor to check the RPM range. I'm only getting 5,000rpm on the water and I wanted to be sure it was from the load on the boat and the prop/motor setup. I had just used the boat fishing for about 8hrs earlier so I know the motor runs fine.

So I hooked up the water hose, started the motor, engaged the throttle in gear, rev'ed up the motor to 5,300rpm and quickly disengaged the motor. Let it idle for a few seconds and turned it off.


Then I sprayed a can of degreaser, let it soak for a 1-2mins, and lightly sprayed off the cleaner with a water hose. With a misting spray, not pressurized.

Here's where the problem starts.

I wanted to re-start the motor to make sure I burned out any water that might have gotten into the heads or any other parts. The motor tried to start and then stopped while the bendix on the starter was engaged. The flywheel wasn't turning and neither was the starter.

After taking the starter apart, I have found the bendix gear turns like it's stripped out. I can turn the flywheel by hand so the motor will turn over easy enough but the bendix is shot.

So is this normal? I just replaced the bendix gear about 3-4 months ago. I don't think it's an OEM part. Sierra or something maybe? I got it from my boat mechanic.

I'm going to buy two more and keep one on the boat in case this happens again. Any suggestions or thoughts about the bendix?
 

CaneCutter79

Chief Petty Officer
Joined
May 24, 2009
Messages
454
Re: Bendix gear slipping, something serious or is this normal?

After a bit of my own extensive research, I have found that newer motor use a two-part starter drive gear (aka bendix) while older motors use a single piece. I "think" the two-piece is made to allow the gear to slip if the force to turn the flywheel exceeds a design load, which protects the starter from burning up.

My question is, is OMC parts that much better than Sierra or Arco? There's not much price difference so I'm going with OMC hoping it will last longer.

I've filled JB-Weld into the bottom of the broken bendix to keep on the boat as a "emergency backup" in case the new one slips while I'm miles away from the dock. I can easily change out the bad one and slip on the old one for a "one time start" to get me back to the dock. So far, JB Weld has held extremely well and I doubt it will allow it to slip ever again. It holds up to 2,800psi tensile strength.

Anyone know the the reason for the two-piece design or the difference between manufacturers quality?
 

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: Bendix gear slipping, something serious or is this normal?

So I hooked up the water hose, started the motor, engaged the throttle in gear, rev'ed up the motor to 5,300rpm and quickly disengaged the motor. Let it idle for a few seconds and turned it off.
Very bad idea!
 

CaneCutter79

Chief Petty Officer
Joined
May 24, 2009
Messages
454
Re: Bendix gear slipping, something serious or is this normal?

Ok. Good to know.

The motor still runs fine so no damage was done. I'm still trying to figure out why the starter drive gear slipped and how often does this happen?
 

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: Bendix gear slipping, something serious or is this normal?

Ok. Good to know.

The motor still runs fine so no damage was done. I'm still trying to figure out why the starter drive gear slipped and how often does this happen?

your assessment is correct...your degreaser caused the friction clutch to slip.

how often it happens? rarely.

I use 3in1 oil on the theory that any kind of grease (or molly lube as suggested in your link from the other forum) will attract dirt.
 
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