I have a d4 serial # 7u 16248 with a serious leak in the front mounted hydraulic pump. After reading previous posts I think I know how to remove the unit just thought I would check with people who have done this before to make the job less complicated. I assume that there is a bad seal, is that the most likely source of the leak?
I will post a couple of pictures to show everybody what pump I have. Thanks for any advice it is much appreciated.
Bulldozer3
Steve Crowson
Monroe, Oregon

Once you get it unbolted from the radiator, it should just slip forward and off the shaft. Make sure you've got good blocking under it. .it's a heavy bugger. Then lay it on it's front and you'll see where the seals are. As I recall, when I did the last one I put a pair of seals in.

Thanks for the reply. I hope to have it off before the day is over. Do I need to go to a cat dealer to get the seals or can they be found at a parts place?

"BULLDOZER3" wrote:

Thanks for the reply. I hope to have it off before the day is over. Do I need to go to a cat dealer to get the seals or can they be found at a parts place?

NAPA had replacement seals and like OG I put 2 seals in
Good luck
Dennie

I got the pump off the machine and the seal removed. Carquest could not match it so will try Napa tomorrow. It is a handful, I will need more help putting in on than I had getting it off. My Dad bought this cat in 1965 but it hasn't been used since 1986. It has been sitting inside and started every year but not moved because of the junk sitting around it. The pony runs good with a slight oil leak around the crank and the big engine runs well. Steering clutches work fine which surprised me after sitting so long. When I get the hydraulic leak fixed I will service it and take it for a drive. I plan on using it very little and mostly just like to hear it run. Music to my ears. I will post more pictures when I get it cleaned up and the blade back on.
bulldozer3

While you're at NAPA, ask 'em for an old CR seal and bearing book. .having one in your library can save a lot of time when you go to get stuff. My method is to measure whatever I need, bearings or seals, and find 'em in the book first, then go get 'em. Beats going in and telling 'em what you need is for an old Cat and getting a blank look:lol:

That tank can be manhandled back into place by yourself, just gotta have lots of various sized blocks, shims and a few prybars. Just go slow and plan each move ahead of time and watch the fingers. .did I mention that thing is a bit on the heavy side?

I haven't had a chance to find a seal for my hydraulic unit yet. The seal that came out of it is a c/r 5f4721 which is actually two seals in one. When you mention putting two seals in I assume that you have found a seal that fits so you put two in, one to seal oil in and one to keep dirt out. Just wondering if I have the right idea before I go shopping for a seal.
Thanks
bulldozer3

That's the general idea. .by using a pair of 'em, you'll also have a seal on an unused portion of the input shaft. By the time the original seal started leaking, it probably also wore the shaft a bit where it rode. If the wear is too bad, you might consider a speedy sleeve.

Little late to mention this, but a pencil sketch would be a wise thing to do before pulling the pump parts out of the control unit, if you go that far. My pump was toast and by the time I got around to putting it all back together, I accidentally put the rotor with the vanes in backwards. With it not working, it took a while before I figured what I had done wrong. Remove and replace again. I also fastened a lifting attachment as suggested by the Servicemen's reference book, located on the top of the hydraulic control unit. I dangled the pump unit from my JD front end loader to re install it back onto the front of the D4. The "Servicemen's Reference Book for Caterpillar Hydraulic Controls and Equipment" has a lot of good information. When I was done following the directions, my hydraulic control unit was like new again.

Thanks for all the helpful hints. I have a 4020 John Deere with a loader so I sat it in the loader to reinstall. Didn't work as well as it could so next time I will dangle it with a chain from the loader, I think that would be much easier. I ended up getting the seals from Carquest. The number is (481837). I did install two seals as suggested with good results. Fortunately I did not have to remove any thing but the shaft. It was in great shape so problem solved. I say next time because when I got it running again I discovered that the engine oil cooler is leaking so I may be taking it apart soon. So my next project is fixing that leak or can I just plug if off. I really would like to fix it like it should be so I assume I will get to remove the hydraulic control and radiator. Dose that sound correct?
Thanks for any advice
bulldozer3