Grinding starter noise

[Luke9]

Another issue with my 300U. When cranking, the starter makes an awful grinding noise. This isn't the high pitch whine of the starter gear spinning against the ring gear and not engaging. Everything is cranking and not slipping. It just sounds like there's a bag of rocks in there with it. The sound is definitely only when cranking and sound like the gear engagement.

The starter has the new style gear and it appears to be almost new. Cranking the starter on the bench, the gear appears to move correctly. I measured the distance from the bellhousing to the ring gear, along with retracted and extended starter gear positions and didn't find anything unusual.

This led me to suspect the ring gear, although it didn't appear badly damaged through the starter hole. I split the tractor, pulled the flywheel and got a new ring gear. The new gear looks very similar in tooth profile, and other than the front of the teeth being chewed up a bit, the old one just doesn't look that bad. I've seen much worse looking gears that still work, or maybe have trouble engaging, but none that make this noise.

I still intend to install the new ring gear, but am concerned I'm missing something else and will still have the noise after bolting everything back up.

Looking at the wear pattern on the ring gear, it feels like the teeth are engaging at the tips. Normal?? If this was a SBC I would be adjusting shims.

As long as it's all apart, is there anything else I can check? Other ideas?

 

[caterpillar guy]

Are there more than one tooth count for the starter drive so you might have the wrong count like a 9 tooth instead of an 8 or a 10 that could make it grind and still possibly work.

 

[BarnyardEngineering]

Has it always done this since you've had the tractor, or did it start doing this suddenly? Were any changes made right before it started making the noise? Replaced starter? New starter drive?

That ring gear does not look bad at all.

I really can't think of anything else to check while you're in there. There isn't much but the starter itself and the ring gear. You've measured the depth and that seems okay. If the main bearings were loose enough to allow the ring gear to move away from the starter far enough to cause bad tooth engagement, you'd have a lot worse problems.

All that's really left is the wrong starter or wrong starter drive.

 

[Luke9]

I've only had the tractor for a couple months. It's been a project since I got it...operational, but needing lots of things fixed. The starter noise has always occured since I've had it.

The starter gear is 10 tooth and seems to match the 39.6mm diameter description of the "new style" gear from this site.

With the starter and flywheel both removed, and trying to run the starter around the ring gear by hand, the gears mesh smoothly. A crude test, but at least there's not a major pitch mis-match.

I don't see any indication that the gear is running out too far forward as there is no marks on the back side of the small gear assembly. Since this gear looks new, it makes me wonder if the PO had replaced it to cure this problem, or maybe the problem started when he replaced it. I have a starter from an H with the old style bendix, which is a different nose cone diameter, but I believe the bendix is the same in either one. Swapping parts might be my next step if the ring gear doesn't change things.

To check engagement depth, I've tried to measure from the pilot shaft to the starter gear with the tractor split, but its tough to assure it is centered. Even hung the flywheel on the pilot and tried to shim it to center just so I could visualize the tooth engagement, but I think I'd need an inspection window with the tractor assembled to do that properly.

 

[Tim in New York]

My 2424 did that for the first 25+ years I owned it. I finally had it repaired - the mechanic was able to flip the ring gear over somehow so a new part was not needed.

 

[Luke9]

Update: The new ring gear seemed to fix it. Don't have the tractor totally back together yet, but as soon as I'd mated the halves I put the starter in and cranked it a bit to test. Horrible grinding is gone.

Also highly recommend bolting the pressure plate in AFTER joining the halves. I hadn't considered that until seeing the suggestion on another post here. Just hang the pressure plate and clutch on the splines loose, so you only have the pilot shaft to worry about. It made for a shockingly simple process!!

 

[BarnyardEngineering]

Works fine, if you've got small hands. With my big sausage fingers with the dexterity of a horse hoof, on the other hand, it's impossible.

 

[Luke9]

I suspect not all models were as generous with the access hole on the bellhousing as the 300U. And it definitely helped having the IPTO spline to hang the pressure plate. If I had to suspend, align and find a bolt hole all at the same time I might still be out there cussing.

 

[Luke9]

Update to an old topic. I previously replaced the ring gear to fix starter noise. It seemed to do the trick, but after some run time, the grinding noise gradually returned. All along it has seemed like a tooth engagement issue, so I started shimming between the starter and bellhousing, first tipping the starter back to increase the clearance between gears. Noise got worse.

Tipping it forward (raising the tail end of the starter) to make the gears mesh deeper made the sound go away. Everything about the bendix gear seemes to indicate it is the correct one. Not sure if the starter housing is bent or something else going on. Visually nothing looks wrong with the starter or pilot hole.

Amount of shim was a 1/2" flat washer, so a bit more than a 1/16"?