Hi everyone!  

I recently acquired a D6 9U, which I have begun working on.  I'm starting this thread to document my work, and hopefully get some good advice and knowledge from folks that know these machines much better than I do.  This is the first cat product I've owned, and the first bulldozer.

The good news:

• The undercarriage is in reasonably good condition
• The main diesel appears to run well when pull started
• All gears on the transmission work.  The main clutch between the engine and transmission works

The not so good news:

• It only turns left - and even that's laborious.  The right steering clutch does not disengage.
• The brake on the left side is not great.
• The hydraulic cylinders for the blade are in poor condition.  The seals are destroyed, and the chrome is badly flaked off.

What I've already done:

• The pony motor gas tank was full of holes.  I've fabricated a new tank that fits correctly under the hood.
• The pony motor carburetor was in quite poor condition.  I've got it mostly sorted out.  Funny having to do such fiddly work on such a big machine 
  
• The magneto didn't have any spark.  This was mostly just a matter of cleaning everything up and setting the points.
• As it is, the pony does run and will start the main diesel.  It's not perfect, though.

Next steps:

• Hydraulic cylinders are coming off, and getting moved in where i can work on them this winter.  I'll blank the lines off on the machine to prevent ingress of debris.
• I need to sort out the steering clutches.  I've been reading the serviceman's guide and threads here trying to get a handle on how to approach the problem.
• All remaining fluids need changed out, as well as filters.

If anyone has advice or suggestions for me, I'm all ears.  

More pics coming in a separate post.

I made an attempt at fixing the pony gas tank.  It was just too far gone.



I fabricated a replacement from 18ga steel sheet, with brazed seams.  The fill neck is just a bit of steel pipe, with some straight (Not NPT) threads cut on it.  I machined out a custom gas cap for it.  The tank is sized to fit under the hood, with the filler coming up through the hood in the correct place.

The carburator is made of some kind of pot metal.  The bottom of the bowl took the most damage.



This took a bit of machining to sort out.



And fixed:

This hydraulic steering clutch... assist?  is puking fluid heavily.



In addition, the right steering control has much more free play in in than the left (working) one.  I wonder if something is broken in the hydraulic steering box?

Welcome! Nice project to keep you busy; After you are done, it should give you plenty of operating pleasure and pay for itself.
Did you check oil levels of the steering booster under the seat cushion? Lack of oil would make it difficult to pull back on the steering.
Looks like your fuel bowl had plenty of moisture in it at one time; glad you have the abilities to make new parts/repair.
Keep on sending in photos and definitely ask questions. Thanks, JM

Welcome  nice work you have done!
if it runs and drives I wouldn’t do anything more until you figure out the steering problem first.   Skinner 

dont rechrome the rams just make new shafts and fit new seals. the seals are available from the dealer. when we did ours we did both rams for a little bit more than the price of just the rechroming for one ram.
the existing rod eye is welded to a new bit of chrome shaft after it has been machined and threaded for the piston. you reclaim the eye by machining through the original weld. the eye has a step machined on it that locates in a bore turned in the end of the shaft to a neat fit

now hopefully the ram barrel and piston are serviceable. barrels can be remade by cutting the ends off and fitting a new bit of cylinder tube and hone to size.
the fittings are SAE code61 and are still readily available at any hose and fittings joint. the hose to use with the original clamp on fittings is sae100R2AT this is a non-skive hose with those fittings. if you reuse the fittings fit new grade 5 fine thread high tensile bolts nuts and washers.

hydraulics hoses are measured in dash size a dash is a 16th of a inch for example dash 12 hose and fittings are 3/4 inch bore.

if you dont have parts books get them if you have part numbers the dealers can help you. also so can a google search. there is separate parts books for the machine itself, the hydraulics unit and the blade. if you become a paid member you can access electronic copies of what manuals are in the members library. the list is constantly growing.

I just put new seals in my power steering unit this past summer. The seals are still available from Cat. I replaced the bellows seals first. I then found out I had to pull the unit out and replace the lower seal on the pump shaft. Look here if you haven't already. www.acmoc.org/bb/discussion-d72/30852-19...6-9u-rescued?start=0 

Thanks guys!

trainzkid88 great info on those cylinders. I was thinking I would probably do as you suggested - I had found induction hardened 1045 chrome plated rod is... not cheap, but not as expensive as I thought it might be! I'll have to see if lathe bed is long enough for the machining work.

Dave, thank you for the info and link about those seals. I pulled the seat today and did a little poking around - as it's all accessible now I'm going to pull the steering unit and reseal it.

I did pop the top cover off the hydraulic steering unit, and found that my right side clutch rod doesn't travel as far forward as the left. So, I think my issues are further down in the machine.

This picture is with no levers pulled, just as it sits:

when we priced ours it was 700 bucks each just for the chroming. plus parts plus labour.
the cousin did them i think he just used a normal chrome shaft i dont think it was induction hardened.