D6 Under-Powered

Mtgstuber,

On my D6-9u I was working it pretty hard pulling a scraper, and it too was running out of power in first. When I would get a load , and hit the haul road in 5th, it pulled fine. I changed the fuel filters, and air filters, and it runs great now.-glen

Thanks 7upuller. Two things I'm trying to wrap my head around:

(1) Why do I get power in 5th, but not in 1st? If it's a filter problem, wouldn't I have an issue in 5th too?
(2) The service manual talks about the fuel pressure gauge dropping from good to normal to caution when the filters are clogged. I'm still reading green.

I've got replacement filters and gaskets, but I kind of hate to tear fuss with taking the hood off, cleaning everything, replacing the filters, and repriming the system if it doesn't need it.

My unit is 9U1417. It's already has new oil filters and I tore down and cleaned the air cleaner about 20 hours ago.

Thoughts?

Mtgstuber,

I would still change the fuel filters if you are having a loss of power. Dirty fuel filters will keep a machine or truck running on average pulls. When grunting the engine on a hard pull is when they fail to supply enough fuel thus resulting lost power. It could be something else, but the first place to start is the filters.-glen

When was the last time you looked into or rebuilt the governor. Slow response to throttle and loading is a pretty good sign of governor issues.....assuming you are getting adequate fuel/air delivery. That's also a pretty early serial number, what's the condition and hours on the motor?

The hour meter reads 06538. Honestly, I'm not sure how to read it. It's unclear to me whether that means it has 653.8 hours on it, or 6538 hours.

I bought it about two years ago. I haven't changed the fuel filter, but I haven't run it much either -- probably put around 20 hours on it personally. I'm hunting around the house trying to find the notes from the previous owner as to what he did. To my knowledge, he had had it since '89. I know he didn't put a lot of hours on it either.

With respect to the condition of the motor, I confess I don't have enough experience to say one way or the other. It seems fine to me, but I may simply be clueless. Is there a good way to judge?

I don't believe the governor has been rebuilt anytime in the last 20 years.

Looking through the servicemen's reference it appears that the governor can be worked on in situ or it can be removed entirely for working on it on the bench. Any recommendations? Any thing I should know?

Oh! One other thing. Is the fuel shut-off valve a ball valve, such that I should be turning it 90 degrees? Mine has a square head, so it's somewhat ambiguous what position it wants to be in.

Yes ball valve. Turn 90

Technically it's a taper plug valve but works the same. Seeing as how there are fuel supply questions it might warrant looking at the valve a little closer. It has a square stem (usually chewed up) and some even have a direction arrow on the stem....also have seen the soft brass stem twisted so that indicated indexing can be off.

Overhauling the governor is best done on the bench.....all the parts are still available except the governor spring which is one of the critical pieces.
Recent rebuild cost for a D4 (same unit) about $500...you do the labor.

6538 hrs. is not a lot but these meters are not always reliable. Does the unit smoke? blowby out the crankcase breather? Use a lot of oil? Have good oil pressure?

If you are unfamiliar with engine assessment best bet would be to find someone that knows these old Cat's have a look at it.

It doesn't seem to eat oil. The exhaust out the stack is good and clean. There is a little bit of smoke out of the oil breather from time to time, but not much.

If the governor spring is a critical part, but not available, what do I do? Is it something that doesn't actually need to be replaced during a rebuild? Is there a source for them? Can it be cut down and reformed? (This is what I had to do for the spring on the pony motor to get the throttle working correctly).

Any experts out there that live near Spokane Washington?