Bob from Kamiah, Idaho says:
I bought the old D4 last year and replaced both hydraulic cylinders.
It is now apparent that the pump has a small leak.
I would like to either repair the pump ( put in a kit) or replace the pump.
local sources don't seem to know anything.
I have looked on the net and have seen many Youtube movies showing this pump, apparently a common item.
Any ideas? Thank you, Bob.

howdy Bob.
we need to know what kind of pump your machine has. can you post a photo??

I'm having trouble with the fotos.
I'm also having trouble calling ACMOC.

that's ok Bob just keep trying or get a kid to help you ! that's what i do.

does the pump mount to the front of the tractor and run off of the front crank shaft? is the reservoir on the fender of the tractor???

Yes, the pump mounts on the front w/ crankshaft.
yes, the reservoir mounts on the fender (right).

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Bob

sorry the pics didn't work for me but it may be you have a laplant choate set up on your machine. google "Laplant Choate" and see if you can find pics of your set up. open the attachment to see some examples.

www.tractorparts.com/laplant_choate.htm

Pictures would be a help but, I need help to do that so I understand not getting them. But I want to offer encouragement to you as I have used several modern pumps on my old Cats. But not as good a option if you want period correct restoration. But if you are looking for a usable dozer go for it. The biggest problem with a dozer is the old stuff was looking to use a lot more volume than the more modern systems. So modern high volume pumps are not common. But if you want to use your dozer you cannot get by with a lesser volume, been there done that and redid it with a bigger pump. Surplus Center in Neb has good selection of pumps at good prices and sometimes has some of the higher volume pumps.

My reply???
Anyway here it is again:
www.tractorparts.com/images/catcrawler/CAT_D4_7U_10798.JPG

This is what it looks like.