Ford 550 Backhoe swing excessive travel

[parish]

Hey Guys,
I just bought an old, 1975 Ford 550 Tractor, Loader, Backhoe with the 4-stick control. I had been using it for about 5 or 6 hours when all of a sudden, the swing started to overshoot a lot. It had been working OK before that but was really sensitive and somewhat difficult to feather to a stop, but manageable. Just took some getting use to.
Today, while using it for an hour or so, the swing got really sloppy. I can see that the swing chain loses tension during the swing, almost enough for it to fall off the sprocket. When I return the swing lever to the neutral position, the hoe continues to swing in that direction, then stops and bounces back. Overall, the travel is maybe 5 or 6 feet of uncontrollable slop.
I have the service manual and parts manual. I tried to understand what might be causing the swing chain to lose tension all of a sudden, but can't seem to make sense of it.
If you have solved this problem on an old 550 I'd sure like to pick your brain.
Thanks,
parish

 

[DJ54]

Check to see if some of the links, or possibly a pin in the swing chain is/are broken.

If you just got this machine, do check to see if the u-joint on the pump drive off the engine has ever been greased. It is impossible to grease it, unless you remove the front cowl. Our mechanic resolved the problem for me, by cutting a, like 6" X 6" hole in the cowling at that level to easily grease it. It looked like crap, but, at least you could grease it. Apparently something they overlooked in the engineering.

 

[parish]

Thanks for the reply.

Yes, that pump drive u-joint is difficult to get at. I have a 545 also wlth the same configuration. I have a grease gun adapter that I made that lets me work that nearly inaccessible fitting.

No, the swing chain is fine. I'm pretty air has gotten into both swing cylinders somehow.

 

[City Farmer]

I have a 4 stick 4500 and had the same problem. At the back of the swing cylinders, theres a line that goes between the 2. I pulled off the line and oil came pouring out. There shouldn't be any oil on the back side of those cylinders because they're only single acting, they only pull. After all the oil purged, the chain tightened right up. The packing in one cyl. was bad. I replaced it and all is good. I've never looked and 5500 before so I don't know if they're the same.

 

[parish]

I have a 4 stick 4500 and had the same problem. At the back of the swing cylinders, theres a line that goes between the 2. I pulled off the line and oil came pouring out. There shouldn't be any oil on the back side of those cylinders because they're only single acting, they only pull. After all the oil purged, the chain tightened right up. The packing in one cyl. was bad. I replaced it and all is good. I've never looked and 5500 before so I don't know if they're the same.

Hey, City Farmer,
I was just posting a new question and decided to look at my previous posts. When I ran across your response to my question more than a year ago, I was reminded that I should have sent you a thank you note. Your diagnosis of a leaky swing cylinder was 100% accurate. So THANK YOU! Hope you're well, and happy holidays.