Bobcat 643

[Mutey78]

Hey all. I borrowed a skid from a friend . Has worked great for a week, today worked as usual, drove it over to wash mud off, and when I went to throttle up I felt a vibration and some kind of noise, so I throttled down to idle and sounded fine, 1/4 throttle felt that vibration and noise so I thought if I went full throttle it might go away. Well when i went to full throttle before i had a chance to move, bad vibration and then heard a loud ping like sound, so i shut it down. Idles perfect, and now a red light it on, looks to be a temp light, but I know machine isnt hot, and now it wont move or the bucket wont raise or tilt up.. nothing happens with pedals, and If i push sticks forward to drive, nothing happens and makes no noise, just nothing. If i pull back on sticks it wont move but hear alot of clicking. It starts and idles as it should, but if I idle up it makes a ticking noise and vibration.. I'm stuck and have no clue what to look for. Please help. Fyi it is an older machine, no buttons or multiple lights. Just turn the key and it starts, pull lap bar down and go.

 

[[email protected]]

sounds like the U-joint let go. kinda a bummer they are a pain to fix-but I think the worst part is the damage they can cause to other things when the metal shards go flying. they have grease zerks that are impossible to reach....I had a 643 for years, I loved it. Sold it a few years ago hopefully its not my old one haha.

 

[Mutey78]

sounds like the U-joint let go. kinda a bummer they are a pain to fix-but I think the worst part is the damage they can cause to other things when the metal shards go flying. they have grease zerks that are impossible to reach....I had a 643 for years, I loved it. Sold it a few years ago hopefully its not my old one haha.

Thanks. I'm not sure if it is your machine. By Duluth minnesota.. anyways, how do you fix the U joint? Is there a trick, or do I have to pull the motor?

 

[Mutey78]

Thanks. I'm not sure if it is your machine. By Duluth minnesota.. anyways, how do you fix the U joint? Is there a trick, or do I have to pull the motor?

If the U joint let go, will that cause it to make noise and vibrate when throttling up ?

 

[[email protected]]

If the U joint let go, will that cause it to make noise and vibrate when throttling up ?

yes. the u joint is what connects the motor to the pump. so if the u joint broke that would explain why you lost all hydro power but the motor still runs fine.

 

[Mutey78]

yes. the u joint is what connects the motor to the pump. so if the u joint broke that would explain why you lost all hydro power but the motor still runs fine.

If you throttle up, the engine makes loud ting noises too now. Only at idle to about 1/4 throttle is runs smooth and no noise

 

[Tazza]

If you throttle up, the engine makes loud ting noises too now. Only at idle to about 1/4 throttle is runs smooth and no noise

Lift the cab and put your hand into the blower housing behind the pump and feel for the universal joint, if it's hanging, it's broken off.
I wouldn't run the machine if you don't need to as the part on the pump may stil be sitting there, if it falls into the blower wheel, you will break fins.
Removing the motor to replace it really isn't too nasty. I removed, replaced and had the machine running in 2 hours once.
4 engine mounts, coolant hoses, power cables, inlet and exhaust lines throttle linkage. Use a chain and hoist to lift up a litle and slide out the back. Reverse to get it back in, but a helper is good to line the universal joint up to the pump, be careful to nit get your finger caught between the two shafts, it can really damage it when your helper bars the engine forward. If it won't engage, get said helper to put load on the motor and turn the pulley with a spanner and it will engage.
Grease the universal joints before putting it in place (obviously)