After looking at lots of neglected junk, I finally settled on a nice 1979 966C, a 30K series machine. It looks well cared for - one owner since new and less than 13,000 total hrs. The maintenance records show that it had an in frame engine rebuild about 3,000 hours ago and the centre articulation redone at about the same time (line boring and new pins and bushings). Other than that, past repairs have been relatively minor. Can anyone tell me the differences between the different series of the 966C's? Cat made the 30K, 25U, 42J, 76J, and 78G, and maybe others. Did they come from different plants and different countries? Are parts and repair procedures the same between the different series? I'm wondering too what are the weak points and strong points of these loaders. Any comments appreciated! p.s. If anyone has an extra manual (operators, service, maintenance, parts, etc) for these loaders, please drop me a line.
I think you just answered that question yourself 1979 model, still going strong, recently had some major maintenance work done, not unexpected at those hours. If you have access to the history and are happy with what has been done and it matches with hours recorded sounds like you might have just found yourself a well maintained one owner never raced or rallied yellow puddle maker :drinkup
I am not sure at the time off production of the C series, how many plants there were making them, besides the plant in Aurora, IL. The 30K series was one that you would see in Canada, 76J was in the US, 42J was Europe, 78G was Asia, and 25U was South America, do not hold me to this. If you need any manuals go on ebay, plenty there. A very good machine, basically bullet proof, as long as you maintain it.
It turns out that a parts manual came with the loader. And I ordered the lubrication and service manuals today from eBay. It may take a few weeks for them to arrive, especially with the Christmas mail rush. In the meantime, can anyone tell me what kind of oil the hydraulic system, transmission, and planetaries take on the 966C? Someone told me that the hydraulic system takes engine oil and not hydraulic oil. Is that correct? Thanks for your help!!
We use 15w40 in the engine, aw68 hydrauylic oil in the hydraulic, 15w40 in the tranny, and 85-140 in the axles. We have a 966c for a back up at our scrap yard....she is a trooper.
Thanks for that info. I looked at the Cat website and found info for newer machines. It mentions using TDTO for the hydraulic system and TD/TO4 for the transmission. I think that the TDTO and TD/TO4 specs replaced the older CDTO and CD/TO2 specs. They talk about using straight grade 10, 20, or 30 oils in both the hydraulic system and transmission. But that just confused me more. I'm wondering if TDTO and TD/TO4 is the same thing, if one oil, maybe a 10W, will work for both the trans and hydraulics? A multigrade, especially if it was the same as in the engine would be even better if that won't do any harm. Another question I have is about the seat belt attachment points; the loader doesn't have a lap belt anymore. The seat frame folds forward to allow access to the batteries. Can anyone tell me if the seat belt originally mounted to the flip up seat part (and if so where on that part) or to the floor underneath the seat. If anyone has a 966C and can have a look at this, I would appreciate it. A picture would be even better, but that's likely asking too much.
The hydraulic system is the least finicky. 10W30 diesel engine oil will work fine as long as it fits in the viscosity range per the temperature chart in the O&M manual. Within the first 100 hours or so in your hydraulic system, 10W30 will simply become 10W as the friction modifiers are churned away with the pressure and flow within the hydraulic system. A straight grade 10W Cat hydraulic oil, or commercial 10W engine oil, or Cat TDTO in 10W are also all acceptable in Cat's Hydraulic systems. The AW68 industrial oil referred to above is "ok" but I would sample it - it should have more than 600 ppm zinc for the cartridge type vane pump in that machine. Cat engine oil usually has around 1300 ppm zinc which is why many people just use that. Cat usually recommends industrial hydraulic oils as a last resort only. 15W40 in the trans (mentioned above) is NOT recommended by Caterpillar as modern engine oils are too slippery for wet multi disc transmissions like the planetary unit in your 966C. You definitely want a TO4 rated oil in the trans. In 1979, engine oil wasn't nearly as slippery as it is today.
We' ve got a 76J 966 . The seatbelt anchors are below the seat frame . Always have to make sure they're down the slot to flip up seat . Real backbreaker getting those 4d' s outa there too . All we have is micro fische parts and service specs . Also have local Cat salvage parts yard for used parts when needed . Good luck with yours .
15W40 for engine oil, and in the older machine will work for transmission and hydraulic too. Or you can use straight 30wt in engine and trans and hyd. 85w140 is a bit heavy in the axles and especially the planets. I'd use sae 90hd, but actually, sae 50 TOTD is better.
Those old 966Cs are tanks. Tough as nails. Up here in canada, I run 10w30 engine, 15-40 is fine in the summer, 10w in the hydraulics year round and 30 wt in the trans in summer, 10 wt in winter.
Oils used The oils we would use in the U.K. is as follows - SAE 10 in the hydraulic system, TDTO-TO4 rated 30 for the transmission and axles, 15/40 in the engine, CAT sell the lot in 20 ltr pots job done. tctractors.
Thanks for the very helpful replies. I now spoke with the original owner and found out more about the lubricants that the machine has in it. That raised a few more questions, which I posted under the Lubrication section of HEF. If you lubrication experts don't mind, please have a look at that. :drinkup
When I was working on those old dogs we used 30wt. in the engine and transmission and AW46 in the hydraulics. I used 30wt. engine oil in the axles as well, because they were external brakes. I never had a problem with any of them on that. I wasn't going to carry mulitple grades of oil with all the containers needing storage. We only used the two types and I only had two barrels on the rack to feed their appetites. I could buy them in bulk quantities and get better prices to go with it. When the loaders went to internal wet disc brakes we had to start using tractor hydraulic fluid in the axles to start with. The oil companies came out with a friction enhancer for the 30wt. engine oil so we could use it again. Today the engine manufacturers want you using multigrade oils in the engine and they suggest real strong that theirs in the only oil that should be used. Now there is special transmission oil, special hydraulic oil and special engine oil. They all have a special price to go along with them. I haven't found a single instance where someone using the SAE graded oil meeting API specifications ever caused a failure.