We have a 753 Bobcat, think it's a late 90's machine. The flywheel ring gear and starter are going out, seems like some of the teeth on the ring gear have worn or broken off so we need to replace. How much of a job is this? does the engine have to come out? sorry for the questions, just haven't had much trouble with the machine. Thanks for any information/help, Patrick
Can't speak directly to a 753, but we had a 1989 743 where I worked and pulling the engine out of it was not a bad job. Unhook wires and fuel lines, drain coolant and remove radiator then undo the four mount bolts and slide it out the back. Held to have a fork truck with a sheet of steel held up to the back of the Bobcat to slide the motor on to. Could also do it with blocking up the steel plate or something solid to slide the engine onto. But to answer the other part of your question I would say removing the engine is required on most equipment unless it is easier to remove the transmission or pump assembly which I doubt would be the case on a Bobcat.
no the engine doesnt have to be removed. you will have to removed the battery rive belt cover the drive belt. once you have the flywheel out, cut off the old ring gear, and clean the mounting surface. set the new ring gear on the flywheel, and heat the inside diameter of the new ring gear with a torch as evenly as possible. the gear will slowly expand and you can tap it into place with a hammer. let it cool and reinstall.
Like I said never had direct knowledge of the 753, I'm a little surprised that unlike the 743 the 753 has a belt drive system for the pumps. 743 has a direct drive via a pair of U-joints to couple the engine to the pumps. I did a little research on replacing ring gears, book I was looking at was for a Detroit but should be in the ballpark. It says not to heat over 400ºF. If like me you have access to a oven in or near the shop I would just put the new gear in the oven set for say 375ºF and let it heat while you remove the old ring and clean up the flywheel. I have done a few that way or when oven is not available use a heating torch and temperature crayon to let you know when you are at 350-375ºF. If everything goes right the new gear will drop right on and even turn free for s few seconds. I always likes to gentility tap them on after they cool off a little to be sure they a seated all the way. Oh and before you take the old one off make sure you know which way the new one should face, some have a chamfer on one side of the teeth.
Ditto to what has already been said, but if you want to survive, don't heat the ring gear in the oven, unless the wife is on vacay. They just don't see the logic and economics to these things, as we do...
Make sure the ring gear is actually bad, and not just the starter gear. A bad starter gear will sound awful and wear the ring gear, but a new starter gear and cleaning up the rounded teeth with a file might get you another couple decades. Of course, I've never done that on a skid steer, taking the engine out might be easier...
Thanks for the help, I,ve changed ring gears on a jeep before, roger on the wife outta the house, next question is there a good place for a replacement gear (other than dealer) I'm outside right now (in the lower 48) so if I could get one down here and put it on the truck it might be better than Alaska prices, just sayin. thanks again, Patrick
That's why when we got a new stove for the kitchen the old one went out to the garage! Now the only "heat" I get is when I forget to move her car out before baking on some paint in the oven. It's surprising how much better even cheap rattle can paint looks and holds up after half an hour at 250ºF.