Very Rough engine idle Deere 490D

I have a vintage 1895 490 D. Use it only very occasionally. Three years ago I had the injector pump rebuilt because it was leaking significant amounts of fuel into the crankcase. Reinstalled it and changer the oil and it ran very well until this year. When I started it this spring it ran fine at speed with normal power but when I idled it down (I don't know exactly what rpm) it started to shake until I was seriously afraid the entire machine was coming apart. Quickly shut it down and can find no looseness anywhere - crankshaft dampener is tight when levered with a crowbar and the flywheel and coupling to the pump is tight and in good shape (coupling was replaced shortly after I bought the machine). I just finished replacing the pencil injectors - the originals were tested and were popping about 1000 psi below the 5800psi they were supposed to. The engine now is a LITTLE improved at idle but still shakes enough to make me NOT want to idle it at all. With the reman injectors in place I cracked each nozzle coupling a little and got roughly the same engine slowing (fast idle) from each cylinder.
Any ideas on what might be causing this shaking? Has it happened to anyone else?

Darn dyslexia! 1895 should be 1985 and 'changer' should be 'changed'

Are you using implements at idle and it's shaking or is it just shaking on idle?

Also, if you can find out what rpm the problem occurs at it might be helpful. Especially if it's simply idling too low, though I doubt that's what it is from what you've described.

Not doing anything hydraulically and it doesn't make any difference if the pilot operating system is activated or not. I don't have any way of knowing (or figuring out) what the idle or any other rpm is. The throttle is pushed hard full forward to mechanically shut the engine down and of course it goes through the shake zone when it is stopping. I'd have to have some kind of variable strobe light to measure rpm at the pump driver and I don't have access to one.

My guess would be one of the balancer shafts is either not turning or has lost a weight.

Could also be a spun main bearing, but usually you lose oil pressure with that... not always though.

You might want to pop the hydraulic pump unit loose, pull it back far enough to disconnect from the drive and try it, just may be something in the pumps/gears.

lantraxco said:

My guess would be one of the balancer shafts is either not turning or has lost a weight.

Could also be a spun main bearing, but usually you lose oil pressure with that... not always though.

You might want to pop the hydraulic pump unit loose, pull it back far enough to disconnect from the drive and try it, just may be something in the pumps/gears.

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Thanks, I'll try to check it out.

Done a little more research - According to one of the listings this excavator has a Deere Model 4045D engine. Going to a parts listing shows n/a for balance shaft (s). Therefore I'm pretty sure my engine doesn't have balance shafts but I'll check with out local Pape shop on Monday.

According to Pape the engine in mine is either a 4039 (3.9L) or 4045 (4.0L). According to their parts list BOTH engines DO have balancer shafts. Bummer!

Fourdiesel said:

Not doing anything hydraulically and it doesn't make any difference if the pilot operating system is activated or not. I don't have any way of knowing (or figuring out) what the idle or any other rpm is. The throttle is pushed hard full forward to mechanically shut the engine down and of course it goes through the shake zone when it is stopping. I'd have to have some kind of variable strobe light to measure rpm at the pump driver and I don't have access to one.

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If it shakes as its winding down to stop with no fuel going in that eliminates a fuel system problem and makes it more likely a balance or crankshaft problem.

Should be pretty easy to pop the oil pan on that series excavator I think. If it was me I would eliminate problems in the basement before going much further with it. If there is a failure anywhere inside the engine, you'll want to catch it sooner than later?

lantraxco said:

Should be pretty easy to pop the oil pan on that series excavator I think. If it was me I would eliminate problems in the basement before going much further with it. If there is a failure anywhere inside the engine, you'll want to catch it sooner than later?

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NOTHING is easy to do on that engine - but some are easier than others. You are right though, if something id broken or disconnected finding it sooner is better than later when the machine is off in the woods in a pile of stickers and the motor won't run. Nothing stays put like an excavator with no motor. Trying to figure out which is a better fix: replacing the engine with a 'good' used one, a reman engine if I can find one, or fix what is wrong in place (if I can get at it). Thanks for all your help.

Four diesel what did the fuel look like when you cracked the high pressure lines? Foamy would cause a lower than recommended rpm and those motors shake severely. I tend to think that is in the injection pump seeing that you had it rebuild a while back.
I've been Working on these things for 30years and I've had many rebuilt rotary pumps fail

Aside from a few bubbles which I expected because I had just put in new injectors everything looked normal. No foam and no bubbles after a short while. Each cylinder seemed to be picking up its share of the running load (high idle). Power is normal to the tracks and the bucket/boom so there doesn't seem to be any lack of fuel anywhere in the power cycle.