I recently acquired a 1969 966C Cat Loader. The engine and brakes have been rebuilt and multiple Cylinder seals have been replaced. There are a couple of issues but the main concern is upon shutdown, approximately a quart(or so) of Hydraulic fluid leaks onto the center pivot area and then onto the ground. Initially the Hydraulic tank was over filled but I do not think that is a cause now, as the level is now proper. It seems to be coming from the upper area between the Reservoir tank and the center of the loader. I am partially disabled due to a injury and can't properly investigate at this time. It will be a month or so before I can physically do what is needed. I am hoping that someone would have an idea of a potential cause. I have ordered a manual and hopefully can get some guidance from that. My grandson helps but is too young to do a lot. Myself, it is a task just to get in and out of the loader at present but I will be fine, other than being impatient!
Can I ask under what conditions exactly that you measure the hydraulic oil level.?
Initially when I got the Machine and determined that the hydraulic tank was over full, I drained it and Refilled with 25 Gallons to bring it into the sight window. Since, I add when I see the level at the top of the window, cold before startup, as level as possible. At first the fluid appears to be coming from the area of the drive shaft and the pivot plate but is actually coming from above, perhaps a pint average the last three shutdowns, moderate work. I am unable to get in there right now to be able to see.....it's frustrating but probably not lethal. I do have an operations and maintenance manual but it is limited about subjects like this.
Tighten every single suction hose clamp you can find. Leaks when the machine is not running are usually suction line leaks that have tank pressure pushing oil out. When it is running, they rarely leak, but severe leaks may cause the pump to pull air into the system and makes for a noisy, jittery operation.
When I am able to, I will be putting a wrench to all the fittings and/or tool surfaces. The loader came to me with 21 hours since a fairly extensive engine rebuild and other shop work. It has been my experience during the last 10 or more years that almost anything I have ran, from Motorcycle to D7 bulldozer has had some mechanical problem or flaw, usually from having been worked on improperly the previous time. I always find something that I have to tighten up no matter what the machinery or vehicle. Most are obvious, perhaps a testament to the degradation of knowledge base or personal pride in a job. I will find out .
We’re you aware that the hydraulic oil level is supposed to be checked under the following conditions - machine on level ground, bucket flat on the ground, all machine systems at normal operating temperatures, engine idling with the transmission in neutral. It is possible that the implement hydraulic tank is slightly over-full.
Now there are a couple things at least that the manual neglected to mention. I have operated a 966C many hours but it was a company with quite a few pieces of equipment and there were 3 oiler/mechanics checking most fluid levels and topping off each shift. We just shut down long enough for them to do their thing. it was a break and the coffee was hot. Probably should have been paying closer attention. Thank you for the info, I am going to write that down in the manual now. Hopefully the manual I have coming is the one I need, this one is next to useless I see now. When it is your money, or even if it isn't... maintenance is critical to a long and productive machine life.
If you supply a Serial Number I can look up the reference of the appropriate Operation & Maintenance Manual for it as confirmation that what you have coming is the correct one. Even a brand-new one from Cat is only around $50 for an electronic version or $60 for a paper copy. Maybe another suggestion would be to observe the oil level from the time when the engine is stopped and see what happens when it is started. Then after running for a couple of minutes shut the engine down and again watch what the oil level does.
How old is the grandson? Just thining that anything over five years old he should be able to do a lot! Any chance he has a cell phone and could take some pictures of the oil as it is leaking? Just remember oil runs down hill so have him keep looking up till he can get a picture of where it wet stuff starts. Also any chance of some picture of the machine from both sides and maybe looking down from above behind the cab. I worked on many 966C over the years and had more tha a few right down close to a bare frame but I'm draying bit of a blank on some details. One more thing please post a full serial number as it will give access to online info many here have.
Just to add a little more to what Nige is saying here is a direct copy and past out of the manual for a 966C:
The Serial# is 76j2480. I am still having to struggle to get mounted and dismounted, will be this way for at least 3 weeks but barring any more snow storms, I have things in shape for spring run off. The Manual I have ordered should be here soon. I ordered the Hard copy, I function better with a manual with some greasy fingerprints on it! I ordered something today that may be very useful for things like this, don't know why i haven't already done it. I am getting a Snake Light/Bore scope/endoscope. I got references and didn't order the cheapest one either! I should be able to sit in the operators seat and look at several things while in operation that are barely visible under normal inspections. Extended through the right spot in the floor plates, the scope may be a very useful tool!
The correct Maintenance Manual for that Serial Number is Caterpillar Publication Reference GEG00180. Covers all machines from first built up to 76J4143. $30 for a download or $35 + S&H in paper form.
Serial# is 76j2480. the manual I have is not the same, I can tell from the watermarks on the Copy/paste from yours and the illustration.
Ignore the watermarks. They only appear when downloading an image from the online system. If the illustration is not the same as the one in the manual you have that’s a totally different story…..
SERIAL#76J2480 1969 966C Looks like the Grandson has been taken back by my Daughter...something about school and wrestling and lord knows what else, she is intentionally vague about those things sometimes, Lol. The manual I have is not the same one you did the copy/paste from. I can see the Watermarks on yours with the manual/media number and others. I do not have that and the copy/paste is not there. It is looking like it may be an individual Cat dealership rendition, missing details such as bucket flat on ground, engine idling, etc. I ran into something similar trying to get info about the #24 cable control unit on my D7 17A. I finally got it straight from the old guy in the back of the shop, cleaning parts and waiting to retire or die, whichever came first. He Knew everything the guys up front thought they did. I am going to obtain a Borescope/endoscope, have a decent one on order. I can see extending it through the floor in the right place and being able to see things instead of just wondering about them! Why, it's almost like magic! Ha Ha, we will see, it is an interesting Idea though. I used one on my septic system and saved myself some troubles but I have never thought about using one for this purpose. Can an old dog learn new tricks/ Are the tricks worth learning? I see that Nige has posted a manual reference. I appreciate the help you guys are giving. It is something that Is no longer common with the changing world.
Thank you Sir! The manual I have is quite a bit different, I suspect that it is a singular Cat Dealers rendition. i greatly appreciate the time and trouble you have taken to put things in order.
Now that looks like a manual! I think I will have to ask for a refund, it's worth a try. I will keep the thread going as I find out what the deal is. It is important that the knowledge continues and grows. It is something that each of us can do without interference from Government or outside malicious entities. OK, the pain killers are kicking in, time for bed! Thank you and Good Night
The manual that I referred to above is a genuine Cat manual. Accept no substitutes, especially at that price……..
Finally had a chance to locate the leak. It is at the final connection for the return line from the left lift cylinder. Been too cold for me to do anything about it but at least i know where to start now.
Sounds like you're on to it, the help on this site is priceless. If nothing else the guru's on here will talk you in off the ledge and that usually gets you to a solution in the end.
Not sure what you are calling the "return line form left lift cylinder" or do you mean the line that goes to the head of the lift cylinder?
Not sure if this will help but this should be the page out of the parts book for the lines to the lift cylinders of you machine.
It's not a return line, forgot it's not my Farmall 966. Been too cold for me to do anything. After 50+ years in the Oilfield, my fingers have been frozen so many times that I have limited feeling in them, have to be careful not to let it go too far. I'm surprised I haven't lost any yet. I drop tools a lot, can't feel them very well. Toilet paper is the worst, not sure what is going on there sometimes! Lol The Hydraulic line is the one that goes to the Far left/upper port on the Hydraulic tank...front/forward side. The leak is at the union, between the Pivot and the Transmission. I found a home made brace/Bracket lying under it with a bolt through it, the bolt that should be in the union. I'm not sure what the brace is for but I suspect it is to eliminate flex in the Hydraulic Hose/line from the Pivot action. I am going to try to attach a couple pictures of it.
It was a particularly ugly winter here, almost doubling the effort needed to do something like this. I do not have a shop big enough for it so it is frozen fingers one more time. The ice and snow are gone, I have gotten most of the feeling back in my fingers. I'm checking the torque on that in a little while and going to work. barring numerous visits by Murphy, I should be able to complete the second part of my project and start building up the infrastructure again. The State Dot collapsed my septic drain field, ruined my main runoff drainage and a couple of other things. To add insult to injury, they are trying to avoid paying for about 30 Prime Rocky Mountain Junipers that were not on the Right of way. I have 4 different types of pictures, including Google earth. This is one time they are going to pay.
The diagram was helpful once I turned it upside down! Lol I was looking at the overall system upside down in the beginning, that was the only way I could see it all at once. I added 4 very bright LED lights......now I can go into town and crush cars at night! Lol Thanks a lot guys!
I haven't had to add hydraulic fluid for months! In the end of this project I must report that the shop that did a $17,000 rebuild in 2009 did well with the engine and Line boring but failed to complete the proper assembly of the Hydraulic transition from hose to hard line behind the pivot. Only one of the four braces was tight, one had not even been installed and was lying on an adjacent cross member with the bolt and washer still on it. The loader had been operated less than 20 hours since the rebuild, when I got it. It took me a while but It runs like a 966C should, squeaking brakes and all!