D3 Dozer, any help appreciated!

[Skirty]

Hello everyone

Just looking for some insight on a 70s Cat d3 Dozer or "Tractor" I just bought. I have recently just bought it though auction and I say 70s because I'm not completely sure the year. I just know from what I have looked up on here that it was before the d3Bs that started production in 79. It has more then a few issues to put it lightly and is in need of some TLC.. The serial number is 79U1141, some of the Issues include right brake clutch wont brake the track so you can only turn left or reverse and brake to turn right, also seems like you really have to push to get it to brake. it was having to be jumped to get going, and looks to have recently had a starter replaced, says 12V on the starter. multi meter shows the alternator pushing 29.1. wondering if they put the wrong starter on it and its a 24V system? Is the clutch wet or dry? I really need a manual and I've seen a few on e-bay I just don't know if I'm getting the right one. Would it be a "D3 Tractor" and have the prefix 79U on the front page? any help is greatly appreciated!

 

[Jimothy]

I don’t know but I like the look of the thing congrats!

 

[Nige]

really need a manual and I've seen a few on e-bay I just don't know if I'm getting the right one.

The correct service manual for 79U1141 is Cat Publication REG01357.
Here's one on eBay that appears to be complete but you should always ask the seller the question. The first page in the buff-coloured binder should be an Index of all the individual documents contained in it.
FYI a new one in paper format is currently priced at $530 + shipping.

 

[Welder Dave]

It's supposed to be 12 volt. I'd say your alternator is the issue. In order for the brakes to work the steering clutches have to release. I'm not real familiar with a straight D3 but it would have valves to operate the steering clutches. If you are driving and push both brake pedals half way down at the same time does the machine come to a stop or does the right track want to keep driving, essentially turning left? On D3B's there are rollers on the valves that get flat spots. I had 1 that developed a leak and needed the spool rechromed as well. Start with the steering clutch valves. May need to check pressure but if the left side is working it's more likely another issue. If the valves are good may need new steering clutch plates. Brakes may just need adjusting but start with the steering clutches (valves) and adjusting them first. Oh, it's most likely dry clutches and brakes. I don't know if wet clutches were even an option on D3's.