Bobcat 753 Squealing without any belts on

[rigpig75]

Hi everybody! I'm a long time reader of this forum, but this is my first post. My teenage son & I have been restoring a late 90's model 753 in order to start up a summer landscaping business for him and a few of his buddies. It's had what sounded like a belt squeal for the last few weeks. We replaced the drive belt and tensioner, alternator belt, as well as the blower (fan) belt and tensioner a few days ago, but the squeal remains. In order to eliminate any confusion I pulled off all 3 belts and fired it up again. Sure enough It's still making a squealing noise at any RPM above idle (no squeal when idling). I tried to use my stethoscope to pinpoint the origin of the noise, but no luck. The squeal appears to lessen as the engine starts to warm up. Has anyone ever heard of this? is there another belt I'm missing besides the drive, alternator and blower? The old drive belt was in very bad shape and there was a lot of caked rubber in the drive case. Bobcat dealer says it could be pin hole in the exhaust? Any advise is appreciated... Thanks in advance

 

[flyerdan]

That's a tough one, you obviously know your troubleshooting and have gone about it the right way.
I'm assuming that the alternator belt run the water pump as well so you can take a bad pump bearing out of the equation. Logic dictates that it has to be either a slipping belt, a bearing fixing to fail, or something rubbing against a rotating mass. If you eliminate all of them, the only thing left would be something internal to the engine; if it was an overhead cam I'd suggest a tower bearing, but an OHV train shouldn't make a continuous squeal.
Hopefully someone will be along with more ideas, meantime, there should be a book for the 753 in the manual thread that might offer some help.

 

[craigb93]

That's a tough one, you obviously know your troubleshooting and have gone about it the right way.
I'm assuming that the alternator belt run the water pump as well so you can take a bad pump bearing out of the equation. Logic dictates that it has to be either a slipping belt, a bearing fixing to fail, or something rubbing against a rotating mass. If you eliminate all of them, the only thing left would be something internal to the engine; if it was an overhead cam I'd suggest a tower bearing, but an OHV train shouldn't make a continuous squeal.
Hopefully someone will be along with more ideas, meantime, there should be a book for the 753 in the manual thread that might offer some help.

I would squirt some oil behind the drive pulley while its running w/ the belts off to see if it stops/ changes. All the dead belt bits could be lodged in the seal. etc. Good luck.

 

[rigpig75]

That's a tough one, you obviously know your troubleshooting and have gone about it the right way.
I'm assuming that the alternator belt run the water pump as well so you can take a bad pump bearing out of the equation. Logic dictates that it has to be either a slipping belt, a bearing fixing to fail, or something rubbing against a rotating mass. If you eliminate all of them, the only thing left would be something internal to the engine; if it was an overhead cam I'd suggest a tower bearing, but an OHV train shouldn't make a continuous squeal.
Hopefully someone will be along with more ideas, meantime, there should be a book for the 753 in the manual thread that might offer some help.

Thanks Flyerdan! Yes the alternator runs the WP. I went around with the stethoscope again yesterday and it seems to get louder towards the drive case. I was also thinking a burned bearing as well. I sure hope not! Appreciate the link to the manual! Cheers!!

 

[Tazza]

Thanks Flyerdan! Yes the alternator runs the WP. I went around with the stethoscope again yesterday and it seems to get louder towards the drive case. I was also thinking a burned bearing as well. I sure hope not! Appreciate the link to the manual! Cheers!!

I'm wondering if it could be an engine mount squeal, or another loose metal part that with the vibration on the motor, sounds like a belt?
I have heard noises like this before that were not what you thought they were.