Case 580C quit mid job! Engine won't hold rpm's

I've put in a lot of work into this machine this summer, and gave it it's first real job today (trenching for water and electric to a chicken coop). I bought it recently after it sat for 10 years. It has run many times this summer without any hint of engine issues. Always started right up and ran smooth.

It ran for a couple hours without any issues. Got about 50' of trench dug out. There was some howling from the front - which sounded like belt noise (not saying it was, necessarily). Still ran strong engine wise (the hydraulics seemed to weaken as it warmed up but that is a different issue for a different day).

The engine started to sputter and the RPM's dropped. Usually I can grab the throttle and get a bit more out of it - and it springs back and goes a bit slower (normal for it - maybe others do that, too...). When it's having issues, I no longer get a bit more speed out of it by pulling on the throttle lever.

- Tried pulling the air filter - no change
- If you let it sit for a little while, it will start right up, run at full speed, but then start to drop in RPM
- It got progressively worse - it runs for only a very short time at full speed now.
- Lots of smoke when it does this. Runs rough.
- Took both fuel filters off and drained out what looked like a bit of crud. They otherwise look decent and are pretty much new.
- Plenty of fuel flow out of the secondary filter purge port (after I added some more diesel to get the level high enough to purge the air...)
- I added some Standyne lubricity formula fuel additive this morning for the first time (obviously wish I hadn't now to make the guesswork easier). Heard this was a good idea for old machines, but what do I know.
- Fuel pump is a Roosa Master Model #: DBGFCC 431-64AJ

Video link of it running. Kinda long but I wanted to show you how it slows down a bit at a time.

I'm guessing at least one of you know what kind of pain I'm in for! Thanks for your help!

-Jason

Did you clean the strainer that is on the back of the injection pump ?

Did you clean the strainer that is on the back of the injection pump ? #14

I did not! Didn't know that was there. I'll check that first thing in the morning!

That's the one that got me before. It surprises me how much fuel is stored in the injection pump also. It will run good for awhile till it uses that fuel up in the pump.

Make sure the return line is clear.

I don’t have a case, but it very much sounds like you are starving for fuel.

My guess is that you need to change the fuel filters again. If you ran the tank low or sucked up enough crap, you very well could have a clogged filter. Just went through that myself on my 555e.

Remove #46 in Tinkerer’s pic and blow it out..
BUT FIRST look thru it and see if it has “crud” in it.. regardless, blow it out with compressed air..
And check the threads to see if they’re rusted..

Here are those parts coming out. I took that one guy apart more and did see some crud... along with some kind of magic glass ball in there...

Got it back together. Ran perfect for about three minutes at full throttle, then started slowing down and smoking.
Shut it down for a couple minutes, then start it up - runs great again for about a minute before it does it again.

I made sure to bleed the fuel at the secondary filter. Not sure if I should be cracking it anywhere else after having things apart.

Removed the side cover on suggestion from pumpguy elsewhere. Paper towel was clean - used it as a catch rag for the fuel that poured out.
I have a feeling I know where this is going. I'm just hoping parts are still available?

You got it brother..
SOMETIMES u can lead a horse to water and THEY DO DRINK.!!!
I don’t suggest u try it..
Some do, and fail miserably..
The parts are available.

Yeah, I'm happy to *not* try this one.
My goal: Get this digging job done and my yard back together if that is possible. Then get this pump off and send it out to get rebuilt.

Pumpguy, perhaps you know of someone that can do this?? :wink:

Fuel tank vent plugged ?
Remove the fill cap and see if it still slows down.
Tried blowing low pressure air into the tank thru the line that connects it to the first filter ? Have the fill cap off if you do that.

Yes, yes I do.. lol
I can probably save u some $$$..
It sounds as if it’s breaking up badly..
U cleaned the checkball connector and it clogged up pretty fast..
IF U REALLY NEED TO USE IT..
Take the connector off the pump and knock the glass checkball out of the connector.. blow it out real good to get the spring and glass out and reinstall..
Just be aware that all that plastic and crud is going back to the tank..
One thing to be aware of is:
Once u knock it out, there’s no tell-tale to stop u when things get real bad..
The engine will start to surge in rpm’s when things get real bad.. once that starts to happen, there’s a real good chance that the engine will run away and u won’t be able to shut it down..
It won’t happen all at once.. u will b able to shut it down in the beginning.. but it’ll get worse and worse.. & eventually the key or cable won’t work..
Depending on my work load, I can knock 1 out in a few days..
If I get it on a Monday, you’ll be running by the weekend..
Good luck.

Hi Tinkerer, I did blow out the return line, and got air out of the fuel cap, so it seems to have a clear path back. It started and ran as normal for a couple minutes and then back to starved for fuel.

Pumpguy, Awesome. I plan on sending it to you, then.

I took the checkvalve fitting out altogether and got it to connect back up without it.
Runs great! Got back to a bit of digging.

I do really need to use it, but your warnings are well received! Hopefully it can get through the day without surging, but if it does and if it won't turn off... what is the best way to kill it? Turn off the fuel valve, but that won't work right away and if it is over-revving I don't need a blown motor. Maybe be ready to open the supply fitting at the pump in short order?

Thanks for everyone's help!

-Jason

Shutting off the fuel at the tank will pretty much guarantee a blown engine... it’ll run 1/2hr off the fuel in the filter..
Pull the stop or turn the key and unhook the inlet to the pump..
I’ve gotten in pumps that have “part of” the brass inlet fitting still in the pump.. lol
I asked the guy what happened..
(Like I didn’t know)
He said it ran away and the only thing he had handy was a BFH..
so he just wacked off the fuel line.!!
Lol

If you are worried about the engine over revving you could try removing the pre cleaner next to the exhaust stack and find a stiff ball or something tapered that will plug the intake pipe and will shut off the air supply.
You may want to pre test it to make sure it’s going to do the job.
Make sure it’s stiff or tough enough to not get sucked down the pipe!
The old two stroke GMC diesels had an emergency butterfly valve that could be tripped in a runaway event.

Yup.. pretty much only 2 ways to shut off a run away..
Close off the air..
Remove the fuel supply..closest to the injection pump as possible..

It got through the day without any issue at all - ran perfectly. I had a 3/4" wrench with me in the cab just in case. Thanks for the suggestion on being ready to stuff the intake, too. There's certainly some elegance to these engines when they just go with only air and fuel.

I got the ditch backfilled and shut it down in a good spot. Going to pull the pump and get it rebuilt - found a guy who seems to know his stuff from right here on the forums!