11/29/20 - Put some more skin on her today. Still got a ways to go but at least she's looking the part a little better.



Pulled the lift cylinders off to fix their pivot bearings. The pegs are quite egg-shaped so they'll have to be machined or sleeved (probably the latter) and then a suitable bearing or bushing solution put into place, kind of like someone posted on here earlier in the journey.

Cat sold make a o ring kits at one time, I think they still do. The kits I have seen had a number of sizes of material and enough to make many o rings. So a bit pricy for your need on this one project. The most helpful part of the kit was a miter box to make your 45 degree angle cut in the o ring material. I have made my own and had good luck with them working free hand. You glue them together with super glue. In this case if you can find a ring longer than needed helps. But industrial supply houses should have bulk o ring material too.

11/30/20 - I realized tonight while cleaning all the hydraulic parts that the retainers had been damaged. Someone has tried to bolt them onto the cylinders without the shims underneath them. This causes the retainer to press on the chevron packing with undue force, in this case enough to bend the flanges on all the retainers as the mechanic (I use the term lightly) tightened the bolts down with what must have been some nasty torque but the packing held firm. I think it's clear the cylinders were leaking and someone thought that tightening down on those bolts would fix the problem. This is also why the cup seals just fall into place now; the bore in which they are supposed to press-fit has been distorted.



I thought about having the retainers machined so the surface that contacts the packing would once again be parallel with the surface that contacts the shim stack. I even priced some new ones and they were ridiculous, of course. I ultimately decided to press them back into shape on my 20-ton press. This took some time and patience, but it worked.


I had to press each of the 'ears' of the flange individually and then measure its deflection with a depth mic. I got all of them to within a few thousands, which is good enough I think.


The bores for the cup seals are back to press-fit condition again, which is a good sign.

I broke down and ordered the big o-rings from Cat so I can get these cylinders back together. I just need the original retainer shims now or a good substitute. The parts diagram calls for a total of 7 shims per side, forming a stack of 0.1076" per side. I also have to get the manual for the hydraulic control because I don't know the proper bleeding procedure after everything is back together, or what kind of hydraulic fluid to use. The stuff that was in there before looked like chocolate milk. Maybe that will work.

Original spec was SAE 10W hydraulic oil, diesel engine oil or engine oil. Comparable to ISO 32 hydraulic oil.
If you prefer to go heavier ISO 46 would be the highest I'd recommend on a well worn system.

Old wrote:

Original spec was SAE 10W hydraulic oil, diesel engine oil or engine oil. Comparable to ISO 32 hydraulic oil.
If you prefer to go heavier ISO 46 would be the highest I'd recommend on a well worn system.

Thanks Magnet. ISO 46 it is then.

The new seals from Cat are different, they dont use the Chevron packs and shims, its just one seal, order the seal pack and you will get the new style, much better. Same with the other seals, order the old number and you will get the updated seals. 1200 ft lbs for the nuts, oil threads when installing, use new nuts also.

I find that on older cylinders with some score marks and bumps and bruises on the rods the old chevron packs are a bit more forgiving than the updated seals. And there is some room for compression when they do start leaking.
I agree with Rome though, if the rods are in good shape then the updated seals are much better.

12/11/20 - Got the cylinder head assemblies completed. I did not order the shims from Cat as they were around $6 apiece and I needed 14 of them per the manual, but the real shim requirement actually turned out a little different. The manual says to put the retainer on the shaft, put the packing in the head and put the head on the shaft, then tap the retainer down into the head and measure the gap between the retainer and the head to determine shim stack thickness.


The standard shim stack size is 2.73mm. The gap I measured was close to this, just a little south of 2.5mm so that makes me happy that it's very close to the factory spec. Now to find some shims...


I rummaged through some stuff I had in the auto shop and found some old crankshaft end play spacers from some job I did a long time ago. They were exactly the right diameter to fit onto the retainer. I just had to notch them for the bolts and then deburr everything. These were then put into place on the retainer.


The manual says after you have measured the gap between the retainer and the head, you should subtract 0.010-0.015" away from that to find the shim stack thickness. This is to preload the packing slightly. The proper combination of shims was selected to satisfy this requirement, and it was all bolted up and put aside for when I get the cylinders done and back on the machine.