I just bought an old 4500.While test driving it the steering worked fine. Once I got it home we let it off the flatbed and then it was really hard to turn left. Great power steering to the right. I got it parked and the next day cranked it up, same issue. I lifted the front wheels off the ground with the loader and turned the wheels, easily, full stroke left and right about three times. I then put the wheels back on the ground and turned the wheels full stroke left and right. This time the power steering worked in both directions twice. Then it was hard to turn left again. I repeated this process two more times. After this I headed inside and did some research. I found this forum and some posts dealing with the 4500 steering issues. This topic HeavyEquipmentForums was very informative telling about adjusting the turnbuckle on the cylinder as well as talking about getting rid of play in the system. The next day I went back to the tractor and started looking for play. This is when I discovered that the pin that goes through the base of the cylinder does not have the nut and cotter pin on it. I've gotten a new nut. Its a 3/4" fine thread but the threads on the pin are a big buggered. I want to attempt to chase the threads but I haven't been able to hold the pin from turning. I'd like to get the pin out to try to chase the threads but it seems the part the turnbuckle attaches to is in the way that is preventing me from pushing the pin all the way out. Is there a way to get this pin out without pulling the cowl and removing the radiator? I'd like to get a nut on this pin to secure it. It may make my steering come back to life If not I can at least see if there is other play in the steering system I need to get rid of. The pin in question is number 19 in the diagram. The nut is number 20.
bump
BTW my tractor is a year 1965 diesel.
Look into thread files. They will have 8 different thread pitches on a file; you need two files for all the SAE sizes and one for the metric. You figure out the pitch and start filing around the bolt until you get most of the mess cleaned up. It's not as fast as having a thread die and cranking that on the bolt, but you probably can get the threads good enough to get the bolt on.
the tiniest bit of play in the actuating valve linkage will make the power assist act up, if you can get someone to turn the steering wheel while you watch you should be able to see which pin or clevis is causing your problem. We had a 4500 that did the exact same thing, it turned out to be a bushing in the valve linkage.
My steering box and cylinder were shot on my 1968 4500 so I did a full hydraulic steering conversion on it and that is one of the best modifications I have ever done on anything. I reccomend it big time instead of messsing trying to fix the old crappy steering that is still not going to be very good after its so called fix. Here is the link to my mod http://www.mytractorforum.com/20-ford-new-holland-tractors/211740-full-hyd-steering-4500-a.html The parts I chose to use are in the 4th post and not what I listed in the first post.
With my mod the old steering box and all the linkage in the nose and cylinder in the nose go in the trash. Actually the stuff in the nose can stay and just ride around up there not hooked to anything anymore, which is the way mine is.
I had never heard of thread files before. I looked that up and i will definitely be getting a set. That may just allow me to get that nut on without pulling the beast apart. After i get the nut on i can get someone to work the steering and see where the play is. Davo727 i read your thread and that's a great job you did there. I'm going to see if i can get the original steering runn9ng without too much hassle. If not then i may do something lke what you have going on there. Its been raining here for about a week. Its supposed to keep raining the next few days. Probably wont be getting around to this til next week.
I tried using the thread file. There's just not a lot of room in there. I can get the file on the threads but it seems like I can't get it to dig in good. When it does try to bite the whole bolt want s to turn and I can't get a hold on it to stop it from turning. I did some research and found sliponlocknut.com. No I am not advertising. I feel like if someone else has this problem there product may be a good solution, at least for temporary. I got two of the 3/4-16 nuts. it went on without a hitch and I managed to get it tight. However it is so thick I can't access the hole to put in a cotter pin. I may take my wire welder and tack a spot on it that I can remove later just so it won't loosen up. Maybe not. Either way my steering now works great. I had my wife turn the steering and then I yanked and pried on everything. Its all tight and all good. I'd still like to eventually get that bolt out and repair the threads as I consider what I have done as a patch to get by on. What has to be done to get that bolt out? It looks like I may have to pull the cowl, radiator and disassemble everything just to get it out. It won't push out all the way as it is because the top bumps into some of the linkage before it clears the hole it is sitting in.
Maybe some green lock tight on the taper will hold the shaft for you, clamped in while drying.