Too lazy to search. '67 D4D 78A7177. Need an O-ring number. The lift cylinder hydraulic hoses bolt to hard lines that attach to the cylinders. One of mine leaks at the bolt flange even with the machine setting. This is just a guess, it looks like if the four bolts holding the hose flange to the hard line are removed, the hydraulic tank will drain. If that is so, it might be a good idea to have the O-ring in hand before starting work. Anybody know the O-ring number, not the Cat part number but the O-ring size number, something a hardware store could identify. Thanks. P.S. To anyone interested in a small dozer for farm or hunt land use, aka; recreational dirt work at a leisurely pace. I have finished what I bought this machine for so am putting a for sale sign on it in January. Under carraige is well worn but serviceable for light use. Engine starts well without heaters, shows no smoke. Uses no oil. I am located in the central Peidmont of NC.
Two problems trying to get that information. First is SIS does not recognize any 78A serial numbers, at least the version I have access to. Second is Even if it did the hydraulic system would not be shown under the tractor, that information is almost always considered a separate item as the hydraulics are an accessory that varies from on machine to the next even ones built the same day at the factory. So if you can find a tag on the hydraulic tank with model number and arrangement number there would be a better chance of getting the correct information. Or if there is a number on the cylinder or line going to it that you want to replace the oring in, that might work. Actually the more I think of it if the leaking oring is at a cylinder a nuber off the cylinder would be the best bet as the cylinders would most likely not be considered part of the hydraulic arrangement. I know you would think so but the dozer blade and cylinders are considered another separate component!
Seems to me last time I changed one I just matched it up from an oring kit I had for my 83J -D4D - yellow box kit form cat - don't remember the number on the oring if it had one though... Most of the orings should be the same size just grab one from a different fitting.
They are not a standard O-ring either, probably a square ring. Don't worry about fixing it, just discount it a little when you sell it to me.
Should not loose too much oil if controls are in hold position and you have lowered all equipment and worked controls with engine off to release pressure. Then you should be able to remove the seal and see what it looks like and make some measurements. If it is a standard oring the there most common sizes for a smaller machine would be a 0210,-214 or -219. I'd be betting on one of the first two. It is also possible that it is one of the D-ring style Cat uses but I'm thinking those came out a bit after 1967.
Might be, my my 1978 D4e used D-rings.
Go to a hyd. shop and ask for a dash 12 code 61 o-ring, better yet see if they have a o-ring kit for code 61 fittings Around here they have a small kit with 6 sizes for 20 bucks and these O-rings are right ones for hyd. Bob
Anyone remember the steel backed seal rings that Cat used before the D-rings?
To be honest, that was one of the first things that crossed my mind but I was too lazy to search.
Can't recall any of the part numbers for them but I know there is a assortment kit of them on a shelf in the shop, at least there was the day I retired back in 2015! I doubt anyone there now has the faintest idea of what they are or what machines they fit!
What's up with 78A parts look up? Have run into it several times, even at CAT. Reason I worried the hydraulic tank contents would wind up as weed killer is because the thing was wet after sitting for quite while, like gravity from the tank was at work. I can see clean fluid on the ROPS plate for the front hoop. Guess it could be disassembled with a couple clean buckets in hand. Never worked for me before but there's always a first time. Actually, if the tank drained out there is another hose that could stand to be replaced, the one from the tank to the pump inlet weeps a bit.
Well it might be worth rounding up some clean 5 gallon pails with tops and drain the system and replace that hose and then remove the steel line and see what size and style the seal is in there. Hydraulic tank should have a drain valve that is threaded so you could adapt a hose to it.
The seals used are a Cat #5F1678 which is a (dash 214) NBR Nitrile (70 durometer) standard o-ring. There is no drain plug shown on the tank until you get to Hydraulic Control s/n 62G510-up.
Well that would be a softer version of the 4J5267 which is a 90 duro dash 214. Old Magnet, do you have the Hydraulic control arrangement number or model number?
That would be a 141 Hydraulic Control s/n 62Gxxxx
Could be they expected you to drain the oil out of the plug in the suction line to the pump? Marked it in red in picture below:
That's not the line group that goes with the early Hydraulic Control tank with no drain. It should be a 4K6275 lines group. Slightly different configuration but does also have a drain plug in the suction line.
Okay, as where I worked we had very few dozers I'm not really up to speed on them. The dozer line of Cats seem to have way more options than front end loaders! buying a new dozer must be almost like ordering a pizza. About the only thing close to standard is the yellow paint and even that is not a guarantee! Just looking at the 4K6275 piping I would not want to have a failure or have dirt get in system as it looks like there would be only one way to clean it out, total disassembly! Bottom of tank would never drain!
Thanks O.M., the -214 is just what I need. Should be an easy item to find. K.S.; That last schematic you posted is the one. The 2J1433(?) hose w/double clamps is the one that weeps and should I drain the tank for the O-ring will replace.
You don't have to drain the tank to replace the O-rings on a pressure hose, will only lose oil in hose. Try tightening clamps on suction hose first may stop leak.You will drain tank when you remove tube from pump. Good luck Bob