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I've got two 1999 175 HP Fichts on my boat and the port motor recently started making a horrible howling/screeching sound while cranking. It doesn't happen constantly, but as the motor cranks it will occasionally stop turning and this sound will start. From where the sound is coming from, I'm almost positive that its the clutch in the Bendix slipping (see red arrow in attached parts drawing). This is designed to happen when the torque rating of the starter is exceeded to prevent damage due to a seized engine. However, the crankshaft turns easily and the motor runs fine. This only happens when cranking. I even went so far as to measure the maximum torque it takes to turn the crankshaft manually with a torque wrench on both the misbehaving port motor and the perfectly functioning starboard motor and they are exactly the same; 38 ft-lbs. I've swapped over the starter motor, starter relay, flywheel cover, and Bendix from the starboard motor and I then replaced the Bendix with a brand new one and replaced the journal bearings (#17 on the drawing) in both the engine block and the flywheel cover. None of this had any affect at all. All teeth in the gear train (on the starter motor shaft, top and bottom on the Bendix, and on the flywheel) appear to be in perfect shape. I'm really leaning towards this being an internal problem with the engine putting excessive torque on the starter gear train, but my hand crank torque measurements tell me that there's no problem. Anyone have any ideas here?
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In essence, what you're saying is that you've replace the complete starter, including the bendix gear... and you're still getting that squealing noise out of the same engine.
I think I would leave the key in the OFF position and crank the engine via a small jumper cable... connected between the large red battery cable that's attached to the starter solenoid to the small 3/8" nut terminal that engages the solenoid.
That would have you standing right next to that squealing, hopefully allowing you to pinpoint the source.
Frankly, I can't imagine what it is after reading your post if it's not the starter. -
I had my son crank the motor while I was standing next to it and it definitely sounds and feels like the noise is coming from the starter gear train or Bendix. I wish I new for sure what a slipping Bendix clutch sounds like.Comment
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The slipping clutch simply slips... no noise that I've ever run across.
The squealing noise thing has always been a dry starter bushing... BUT... you stated that the starter from your other engine worked fine on the engine it belonged on but squealed when put on the problem engine.
Now, that's weird!Comment
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Actually, the starter that I put in was a spare used starter that I keep on the boat. I didn't swap the starter over from the stbd motor like the other parts. I suppose the used starter (which I had never run before) could also have a dry bushing?? Hard to believe. Also, if it was a dry bushing in the starter, wouldn't the motor continue to turn while the sound is happening? The engine stops turning when the sound occurs, which is what's making me think it's the Bendix clutch slipping. I don't know if the clutch is a friction-type like a car clutch or if it's got spring-loaded interlocking teeth. If it's got teeth then it might make a lot of noise when it slips. You know for a fact that it should be silent when it slips?Comment
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I've had those clutches slip right in front of my eyes... the starter armature would be turning and the flywheel and bendix gear would be just sitting there motionless and quiet.
I admit that in my 30+ years of experience, I've never bothered taking one of the bendix gears apart to actually look at what was inside but i a$$umed it would be similar to a vulcanized motor mount... not an actual clutch but more like a shock absorbing type component.Comment
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