631D's Purchased - What to Watch For?

[631G]

We recently acquired 3 631D's and a D9G to push load with in an effort to get more competitive on our per yard cost. Generally speaking the machines are in decent shape, but I wanted to ask the forum what things that we should be aware of and to keep a tight grip on while running these units. They're all 24W series and up so all mid to early 1980's models. Hour meters all long ago were broken best I can tell, but the necks are weld free and generally tight. So far I've only had to replace a hose or two, but I get the feeling there could be injectors or fuel pumps in the future on at least one of the units based on how its running. Any input is greatly appreciated.

 

[Dave Neubert]

Ring and pinion are known to go out

 

[Questionable wizard]

Oil sample the transmissions and differential sections. Can give eminent warning of problems. If nothing else, check the magnets on the drain plugs. Hold a running shop vac hose to the fill opening and you can take out the drain plug and lose very little.

 

[631G]

Oil sample the transmissions and differential sections. Can give eminent warning of problems. If nothing else, check the magnets on the drain plugs. Hold a running shop vac hose to the fill opening and you can take out the drain plug and lose very little.

I think that we’ll give this a shot. I like the idea using the shop vac. Will have to give that a shot.

 

[631G]

Ring and pinion are known to go out

Good to know. Was this specific to the earlier models or just a general fact with these machines?

 

[Tinkerer]

Check the wide open throttle rpm's.
I pushed 631D's a lot of miles on haul roads and in dump sites. The mechanics found that several of them were not running WOT because of throttle linkages needing adjustment.

 

[631G]

Check the wide open throttle rpm's.
I pushed 631D's a lot of miles on haul roads and in dump sites. The mechanics found that several of them were not running WOT because of throttle linkages needing adjustment.

Thank you for this info. I have to have the tach repaired on one unit as it stands now so we'll dig into it. before I dig through the manual I bought do you know the correct range of RPM's?

 

[Tinkerer]

I'm sorry, I don't know the WOT rpm's.
I never ran one. I only pushed them.
If I remember correctly the company had a fleet of 12 of them.
The 631C's would pass them all day long.