Hello to everyone on the forum! I am a newbie, so please forgive me if I make some silly mistakes. Last year I got serious about getting a track loader for my property to do some tree removal/stumping. I have always thought 973's were the coolest machines to have graced us with their presence, so I started looking for one. After about a year of looking, I came across one that had a good running engine and drive but other issues that made it cheap. I have really enjoyed the process of getting it usable and working again. As I am working on various leaks, there is one that I am hoping to get some of your all's input on. One of the finals is getting filled with fluid from the transmission. It is significant enough that I want to try and tackle the repair when I get to a good stopping place. My question is, is that fluid likely to be leaking from the brakes or the drive motor? Also, am I insane to try that repair on my own? My machine has 23,000 hours, but has obviously been rebuilt a time or two along the way. Serial 86G01240 Thanks for the help!
First question. Have you got parts manual and a service manual for it yet.? A machine from that early generation you are most likely going to need it.
I have both. They’ve already gotten me out of a jamb where the Cat dealer didn’t have complete part diagrams.
I would guess the brake. Does your machine have a brake release pump some machines had them
Mine doesn’t have the built in pump, unfortunately.
there is a way to pressurize brakes with a external pump but you need to have a gage in line so you don't go over 200 psi
Is the external brake release procedure using a volume pump not in the service manual.?
I believe it just gives you a fabricated tool number
So it's not this one.?
Yep
Sorry that’s it.the only thing it has a relief valve to keep you from over pressuring the brakes
I found it in the service manual. I'm somewhat surprised that the OP, who has a service manual, was not aware of it. I wonder if he has a genuine Cat service manual.? For an 86G machine it should be SENR2454.
My manual is from Cat and does have that info in it. The manual has a reference to the early machines with a built in hand pump for releasing the brakes, which is what I thought Pittsburgh Cat Man was referring to. I don’t have anything at the moment that will sub for a good pump, but I can change that. I take it if I rig up a pump and pressurize the system, if the pressure bleeds off, I have a leaking brake. Is that where you all were headed?
Yes that’s what I was getting at I was thinking that an early book wouldn’t mention the pump. Also some of later machines with steel mill arrangement had a totally different pump that was mounted in the cab.If you do put a pump on it remove the line from top of hystat to the constant bleed valve witch is on the frame under cab on upright it is a jic fitting you will need to put gage between constant bleed valve and pump don’t go over 200 pounds it will damage hard parts in brake
Good to know! I appreciate you all jumping in on this. I’ve read some of your posts in other threads, and it’s very generous of you to share your expertise. I’ve always wanted a machine to shove dirt around, but I’ve been surprised how much fun I’ve had doing repairs as well. The next big item on the to do list after this leak is repacking the lift cylinders. Haven’t figured out how I’m getting the 4” nut off the cylinder rod yet.
A 973 will definitely push dirt I’ve seen them in the steel mill lift and load a chunk of slag that a 983 could pick up. A 1 inch impact might get the rod nut loose depending on who put it on.
I would suggest take it to a hydraulic shop and have them bust the nut loose for you. They will have the tooling. I've seen (and used myself) all sorts of home-brewed wrenches for getting piston nuts off. Here's an example of a home-brewed wrench. Sit the rod assembly on a shipping pallet. Hold the eye end down with a wheel loader bucket, and use an excavator bucket to heave on the wrench. The nut did come loose.......
Nige I use your same method on the back of my truck but to get the proper torque when going back together I have a 2000 lbs hanging scale that I put on my crane hook. I have made a large adjustable wrench with holes for a 7/8 shackle every 12" so with my 5' wrench I can go to 10k lbs with some fairly simple math I can get a piston to well within spec very easily. The very first time I tried this was actually for all 4 cylinders on a 973. I torqued them to spec on the back of my truck and then took them to a local shop where I get all of my seals from and had them check all 4 nuts and was within 8lbs of spec. I have since improved how I hold them down to the truck and the truck itself and also made the large adjustable wrench instead of cutting a new wrench out for every size but here is from those very first 4. It is still amazing to me what all I put that old Wilton vice through. I believe the highest torque i ever did wit that setup was rught around 8000 ft/lbs but I still have the ole girl and it is still as smooth as ever.
If we were re-using the same piston, rod, and nut we would do the lazy thing and mark the nut in relation to the rod before removal then simply tighten it back up to the same place.
That’s a clever use of the crane, and it’s amazing the vice put up with that! I will at least attempt a home brew method of getting them off, but I found a local hydraulic shop who will torque them down for me. I would like to have a 1” impact, but I just don’t have the air supply to make good use of one. Ingersoll Rand makes a cordless one that I hear is seriously stout, but its price is pretty stout, too. I may end up with one eventually, but my list of tool wants is bigger than my budget. Oh, well… I’ve got a hand hydraulic pump on the way, so I will give you all an update on the brake test in a week or two.
I think I would see how much the cost of them putting the head seal on and the nut on and off might save you a lot of grief it doesn't take long to put head seals in
Without knowing your experience level with rebuilding cylinder but the top or flat pat part of the seal always goes away from what you are trying to keep in or out. So on your wiper the lip goes out or faces away from the piston nut and the pressure seal goes the opposite with the lip towards the pressure and the flat side away from it. Same applies for buffer seals. The backup ring always backup the seal so it is away from pressure. I have tried grease and oils and all sorts of other lubricants for assembling cylinders but the very best I have found is Lucas Assembly Lube. It is a green super sticky slimy snot and reminds me of the old cat cam lube but I use it on everything from filter seals to piston seals. If you have to drive the rod into the barrel with a bfh make sure you install the pin through the clevis. Try to avoid hitting the ears if at all possible but if you do by accident keeping the pin in will make sure the pin pores don't get egg shaped
I’m really new to working on heavy equipment and hydraulics, but I’ve watched a lot of C&C Equipment. lol I‘ve worked on a lot of cars over the years, so I at least feel comfortable around mechanical stuff. I really want to do as much of this myself as possible just because I enjoy the work and am looking at it like getting an education. Even if I have to redo something, it’s not the end of the world. I didn’t ask about just doing part of the job, but the local shop wanted $800 a cylinder for a repack. Any tips/advice is appreciated, so I will keep that in mind about the assembly lube. I actually have some sitting around.
My tip would be regarding parts and getting the correct ones for the actual cylinders you have on your machine. The problem is that unfortunately the as-built information no longer appears, so you have to look for physical evidence. There are 5 different types of lift cylinders from what I can see, and at least 2 different types of tilt cylinders. Look on the cylinder barrels close to the head joint and hopefully you should find a plate. If it is there it will have the Part Number of the cylinder, e.g. 3G5949-00, or -01. Something like that.
Continuing on.... Check the head of the lift cylinders, Ref #9. There should be a Part Number cast into it. Is it 6E-5526..? While you're at it, look for a Part Number cast into the head of the tilt cylinders as well.
Sorry for the radio silence. It’s been a busy week with bad weather, too. My pump did come in, so I will share the results on the brake test soon. I’ll get the numbers off of the cylinders as well.
Paid to have 5 of my cylinders repacked,on my Case580k over the years,not cheap!Then I decided to give it a try myself,bought gland tools,seal install tool 3/4 impact ,have done 3 since and have no problem doing them, I leave the barrel on the machine,and heat the bolt on the piston to loosen it.
Leaving the cylinder barrel on the machine is a good idea if it is feasible. In the case of this machine it’s a nyloc nut that holds the piston so the application of any heat would destroy the locking properties of the nut.
That makes sense,plus im guessing getting that nut on the piston loose is going to be a little harder than my little 580 lol.
Something to keep in mind on your 73 is to make sure the bucket stops are where they should be the one i did both bucket cylinders were mushroomed from bottoming out the rod in the barrel instead of bottoming out on the stops. Makes for a real treat getting the nut off.
I’m back! I finally got to give the 973 some attention. I have the hand pump for testing the brakes. Now it will just take a trip to the hydraulic shop for some fittings to hook it up. Here are the numbers from the cylinders: Boom - 3G 218 I’ll attach a photo of the data plate, since it only being 5 digits seems weird to me. Tilt - 3G5949 @1466IH I wouldn’t have thought to look at that, but the owners before me apparently knew about it. They welded some 1” plate onto the stops. I hope they did that soon enough to prevent any damage. It seems like the people who used this machine tried to take good care of it.
make that 3g0218
Here is the parts breakdown for the 3G-0218. A complete seal kit for the cylinder is Cat P/N 245-0606 (or the aftermarket equivalent)
Here is the listing for the 3G-5949. There is no kit listed for this one.
Thanks, Nige!