IH 686 gear Tractor Starter issues

Hi all, looking for some advice on a starter issue...here goes. I inherited this tractor, 686 gear with a 312 D...1978, according to the SN#. Two years ago, previous owner replaced the starter...the brushes and such were simply worn out. The starter was exchanged at a local re-builder and the core is gone. The replacement starter wont engage the ring gear, all measurements have been taken...the Bendix hits the flywheel ring gear and grinds but wont engage. This is the 3rd rebuilt starter and none will engage. Last week, I ordered a re-manufactured starter from local IH/Case dealer...same problem. Ring gear is in great shape, starters bench test fine, pinion depth engaged and at rest are correct. All 3 starters have a 10 tooth 1.255 inch drive diameter with the rotation of CCW. Any suggestions would be greatly appreciated!!
 
You say the ring gear is good but it doesn't sound like it. With starter removed trans in neutral rotate crankshaft 1/2 turn,
install starter.... now what happens? Let us know.
 

Barred the engine over before ordering the new starter. 180 degrees apart is the normal wear for a ring gear that age but, still left the engine in the position where there is what appears to be NO wear what so ever. You can see where the pinion hits the ring gear and turns but wont engage.
 
(quoted from post at 11:02:24 05/26/19) You say the ring gear is good but it doesn't sound like it. With starter removed trans in neutral rotate crankshaft 1/2 turn,
install starter.... now what happens? Let us know.

Two comments...

1.) The ring gear wear patterns on a 6 cylinder would be 120 apart.

2.) Sounds like the solenoid is making contact and powering the starter too soon during starter drive engagement, so the starter is already spinning FAST when the pinion reaches the ring gear.

"Reman" stuff now on the market often doesn't seem to conform well to the original "specs".

On the other hand, if the distance from the starter mounting face to the face of the ring gear is for some reason not correct, that could be an issue.
 
I say you are getting the wrong starter. Probably one for a hydrostatic drive. I would have
the parts guys really do some checking. Maybe even someone knows of another tractor like yours
in the area to check against.

I know what I would do is remove barrel and solenoid from starter and mount it and operate
plunger by hand to see if it possibly will ever engage. Nose cones can look identical but be
just a bit different.

The 706 gas tractor had a mixed up starter situation and also the 656. Some just different nose
cones, others with different number of teeth on drive and some ring gear. Has been discussed
on here before. Old service bulletins are about the only way to really research it and a dealer
should be able to access all old bulletins if they really try.
 
I agree with Pete, the nose cones on these starters look identical but they are almost the same. The centerline of the shaft is different with the nose cones. Just another reason on some tractors you need to have the original starter repaired.
 

Hello Pete, just to clarify a few things...I think the Hydro and gassers used the same starters. They had a 9 tooth bendix and eventually went to a 10 tooth. The Diesels all have the MT-25 Delco starters with 2 screws per pole shoe and the Hydro/gassers used a lighter duty starter which is shorter and has only one screw per pole shoe (Maybe MT-20?) so, Im certain the series of starter is correct. The boss to leading edge of the ring gear is 2 1/4 inches. The flange to the leading edge of Bendix drive is right at 2 inches in the non - engaged position. When Bendix is fully extended, it should mesh just fine with the ring gear.

Im leading more towards the starter spinning up quickly before the Bendix engages with the flywheel but have no way to adjust or verify...
 
(quoted from post at 11:11:18 05/26/19)
I know what I would do is remove barrel and solenoid from starter and mount it and operate
plunger by hand to see if it possibly will ever engage.
Scooter, Pete just explained how to check/(verity) it
 
Take the starter apart. put the armature and drive back in the nose cone bolt the nose cone back on
the boss. look in there with a good light and see what is going on. if there is a motor end plate
in the way of vision, put a piece of modeling clay on the ring gear where the pinion hits in a thin
strip. Then do as I indicated and turn the armature looking at the clay will tell the story. Jim
 
Make sure you have the longer solenoid that
mounts on top of the starter.It will allow
the bendix to travel farther towards ring
gear.
 
(quoted from post at 04:32:35 06/01/19) I'll go with wrong gear or drive on shaft.

Because of my schedule, it was hauled to the dealer. I got it started by pulling and ran great. The hydraulics worked for a bit then they got slow and steering went away. The dipstick was all foamy so, I'll add 5 gallon to the reservoir and see if that cures it.

Out of curiosity, when we went to unload it I had the guy try to start it. The Bendix engaged but burned the positive cable end off of it...found the problem! The tractor may have had two 6V batteries in series or two 12V parallel, not sure. My thought is to replace the cables with the right gauge and install a 2nd battery on the left of the operators station.

That tractor has 10K hours on it but has had an easy life. All the sheet metal is present and in great shape. The guy gave me a hay wagon, post hole auger, weights and a IH 2001 loader with it.
 

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