My nephew's 1970's-era John Deere 650 has been stored at our place for the last year until he finds a place he can use it, and we've put maybe 10-20 hours on it, finding it runs well, despite the usual dings, rust, and some minor repairs needing done. The other day when it was super-cold, we started it to plow snow, and he was shocked that the hydraulics "wouldn't work". As a novice to the farm-tractor world, I'd read the manual when we adopted it, and knew there was a bypass-valve which you could turn to warm-up the fluid when the weather was cold. He'd never heard of such a thing (we'd also known it from when we had a bulldozer a few years ago with a similar feature). Anyway, we went to let it idle and warm up awhile with the bypass on, and were ready to use that time to dig out the scraper-blade from the frozen ground it had settled in to. My nephew, still bothered that something must be wrong with his tractor due to the hydraulic 'not working' right at startup in the zero-degree weather, decided it was silly to have to pick-axe the rear blade out of the frozen ground, and
just told my son to 'pop the clutch' to jerk the blade from the ground. Having heard (dunno if true) horror stories when we had the bulldozer of dozers being damaged majorly if their tracks were frozen into the ground and someone tried to 'drive' them loose, I started to tell my son not to do so, but it was too late, and there was a loud 'pop' noise, then a repeated 'klunk' every half-second or so accompanied by a jerk of the whole tractor, until I reached over and shut off the ignition. We
hoped it was just a clutch with surface rust or ice causing it not to slip appropriately, but now I'm not so sure.
We DID still have to pick-axe the rear blade loose before the tractor would move, so I guess I was right about not trying to force equipment to move if it is frozen-in, at least in terms of it not working anyway.
Was I also right about it being potentially damaging to the tractor...?
The machine since then runs fine, shifts into all ranges ('hi' is 2wd, and 'lo is 4wd) and gears ok, but there is a decided 'klunk' you feel and hear approximately every revolution of the rear wheels. It
seems to be from the left side, but that's hard to tell. It isn't too noticeable if you're on soft ground or going slow pushing a bit of snow, but on pavement it is really a hard jerk and loud noise, regardless of what gear or range you're in.
I'm thinking a tooth may be off some big gear in the rear differential, but I know nothing at all about tractors. The tires are old, starting to get fine cracks, and the rims have rust around the valve-stem hole made worse I expect by the calcium chloride solution I'm told they weighted the tires with. The tires flex similarly throughout the revolution, so I don't think the solution froze, or that there is merely a tire defect we're feeling - the noise is too hard and metallic for that. The only other thing I could think of was if a shear-pin somewhere had sheared, but I'd think all that would do would be make one wheel not have power (I haven't really figured out how to 'test' that; both seem to spin a bit on slick ice if the bucket hits deep snow).
Is this something we could inspect ourselves and at least diagnose without renting a trailer and taking it to a dealer?
Suggestions welcome.
Any ideas?