I'm definitely the new guy here. Been lurking for quite awhile finally joined. I have a rd4 and it developed a problem recently thats got me some what stumped. Haven't run it since last fall and when I went to get it going this spring the main engine crankcase was full of diesel. It had drained the fuel tank. Apparently there is a valve somewhere where the fuel line enters the main body of injector pump but like I said I'm stumped. Any advice would be greatly appreciated. Also, could someone tell me the year of serial #4G4934W, thanks in advance.

Diesel fuel can leak down the shaft of the transfer pump drive and into the engine sump not a big problem too fix, do you have a parts book? regards Andrew

Usually any leakage that gets past the first seal on the fuel transfer pump drains out the tell tale line that drains the cavity between the outer and inner seal. If the drain line is plugged or the seals are really in bad shape fuel can get to the sump.

The more common cause is the "O" ring seal between the fuel tower and the injection pump. These dry out and allow fuel to drain to the sump. You will have to remove the injection pump/governor assembly to get access for replacement.
It's the "O" ring in the upper RH corner of the fuel tower flange shown in the picture.

Your RD4 serial no. 4G4934 shows to be a 1937 year model. 1937 was the year Cat changed from RD4 to the D4 and my book doesen't show ending serial no. for RD4s and starting no. for the D4.
Starting no. for the RD4 in 1937 was 4G3663 and ending no . for D4 in 1937 was 4G 8857 , but book doesen't tell at what no. they changed.

Happy tracks.............Claney

G'day Old Magnet,

I can't find the part no for that o ring, do you know what it is?

It's the one that barely shows up in some of the parts manuals.....on the fuel injection pump....Pt. # 8B4967

Correction:
The 8B4967 seal started with tractor sr. no. 7J819.
Prior to that it is a 2A3854 on the early J models but I do not have a 4G manual to check.

I don't have any manuals for this tractor. I guess I'll have to start at the transfer pump and work my way in. My grand father bought this tractor new and he always claimed it was a 1939. Maybe his memory wasn't as good as he thought. Maybe I'm dense but I can't seem to find a drain for anything but the top of the tower. Does this thing have a D4400 block, 312 cu.in.?

Yes it is the D4400 engine. Check around for the tell tale drain line. The pump drain line is often t'd into the tower vent drain line and or the injector pump tell tale housing drain line. Again I'm going by the 7J1 parts book but I'm pretty sure they are the same.

Thanks for the p/n Old Magnet

OM part number is correct for 4G as well, regards Andrew