Komatsu D75 S-3

[Mark Meister]

Hello all I figured the forum would be a good place to ask my questions. I just bought a beast of a dozer for clearing about 15 acres of brush and stuff. Its a 1979 Komatsu D 75 S-3 crawler its a 46K lb. beast but my question is when running it the motor lopes up & down not bad but I would like to fix it from doing this. It has a Cummins motor I think its a NTO 202 or 220 at least according to some stats I looked at it is a 6 cyl. 200 horsepower. Its been sitting quite awhile I think the PO has been starting it from time to time but not working it

So I'm wondering does the fuel pump need rebuilt or the governor need to be changed or does it just need run? Another thing it does every once in awhile it will jump out of reverse it won't do in forward gear the PO says it doesn't make a noise it just stops moving and then he just puts it back into gear he think it might be the shifter control valve, when I was running it I couldn't make it do it. So what do you diesel mechanics think? And thank you for anything you can tell me.

Mark

 

[DMiller]

Not much to go wrong with a PT pump, these use a small transfer tank for the fuel side, many times these will garbage up and need removal/cleaning as has been posted on the forum before.

 

[Mark Meister]

Thank you for the reply DMiller . I was just reading about the float tank today that can cause some trouble, thanks again.

Mark

 

[RZucker]

Thank you for the reply DMiller . I was just reading about the float tank today that can cause some trouble, thanks again.

Mark

If it's been sitting for "some time" the bottom of the main tank is probably full of rust flakes and lord knows what else. I would take a good hard look inside and possibly drain and wash it out. Just had to do that with my trusty old 91 F-800 that gets used weekly. Rust? Yep.
Oh, hello from the Files.

 

[Mark Meister]

Thanks for the reply RZ. I know what your talking about I bought a Case 580C backhoe a few yrs. back and it had a rusty tank and like you say the rust flakes are giving me trouble now. I have to take the fuel line off and blow air back to the tank to clear it, you have to pull the motor to change the tank. You mean as in the Fal files?

Mark

 

[RZucker]

Thanks for the reply RZ. I know what your talking about I bought a Case 580C backhoe a few yrs. back and it had a rusty tank and like you say the rust flakes are giving me trouble now. I have to take the fuel line off and blow air back to the tank to clear it, you have to pull the motor to change the tank. You mean as in the Fal fil

Mark

Yep, the Fal files.

 

[Mark Meister]

Well ain't this a small world. I guess I shouldn't be surprised that a heavy machinery mechanic hangs out on a forum dedicated to these machines.

Mark