D4 6U Hydraulic Ram Leak

Hi guys. Recently brought a Caterpillar D4 6U back to life. Thank you for all of the information on this forum. Could not have done it without you. I have a leak on my Ram and would like to know if it is possible for me to replace the seals/rebuild. Im a 30 year mechanic. Are there still parts available? I believe i have a # 44 front mount hudraulic unit. Any advice on removing and repairing would be greatly appreciated. Attached is a picture. Thanks in advance.

Looks like the rod is badly scored - might be difficult to stop the leak. Hydraulic shop should be able to fix you up with seals. - cts

Fitting seals won’t stop the leak with those scores in the rod. Hydraulic shop should be able to make a new chrome rod and supply seals. Might pay to hone the end cap to remove any burrs that might damage new rod.

Like everyone wrote, put a new chrome rod in, get a set of seals either from Cat or an hydraulic supply place (or ebay) and you'll be all set. The rod will need to be threaded on one end for the piston and welded to the eye on the other end. Check the other ram - if it's looking suspect, then it would be worth doing both if you can negotiate a "bulk" price for the machinist

I would not bet against that ram working for a hobby machine. It depends on if just the chrome is flaking away or if it feels ruff on your finger running it across the area. All CAT rams similar to that I have been in are V packing rings. The aluminum piece in front is plunger to keep pressing more on the packing as it wears. You start with a gap between aluminum and the steel. Tightening the bolts as it starts to weep.

The V rings are said to be expensive as compared to o rings. I never found out. A case of the right place at the right time. A friend of a friend had given my friend a large stack of them. I think 6 to 8 would be normal amount on each ram. I put something like 10 on each. I did not do a large amount of dozing with my D6 9u. At least 80% farming but the rams and hardnose stayed on all the time. No leaks in the years I ran it. Unfortunately, that 9u needed transmission work. And other 9u's started following home almost. So it has sat to long, and I got to old. Maybe the SIL and grandsons will fix it.

The friend with the V rings had a shop fire about a year later losing many hard to find little pieces.

But yes for more use a new or rechromed rod is the proper way. But that vintage hydraulics is far more forgiving than newer higher pressure systems. The Cat pumps of the day ran 1000-1200 PSI, a far cry from 2000 on up for more modern things.

I did not look at picture enough. I see BeGe hydraulics pressure could be even lower.

Looks like you still have shims behind the packing gland, you could try removing some (originally had four) but not likely to be a long term fix with that rod condition.

3F9609 IS the part number for the V packing stack, i got a few sets on ebay for $16 each, fixed my leaking rams on my 7U D4

and not the D4 in my profile picture, it was one that had same Cat cylinders as yours

My
D2 is definitely in the hobby machine category. It is just used for small projects several times a year around the farm. Anyway, after I first bought it, I had an excellent local farm shop put a new master clutch in, replace the tracks with a used set I had, and go over the machine. The hydraulic rods were scored similar to those shown. He filled them in with a JB Weld type epoxy and sanded them smooth. I don't know if it was JB Weld or some other material. Knock on wood, but they have held up fine for many years now. It is not exactly a professional solution, but it worked well enough for what I use the machine for.