JD 240 won't maintain rpm / knocks like a jackhammer !

[JD4440]

I have a 240 that almost since new (1143 hrs now) has had this condition. It knocks like injector knock but worse; sounds like your holding a jackhammer to the engine block. It's annoying but the worse problem is during operation it will gain what seems like a couple 100 rpm with no input from the throttle lever. You can idle it back down with the lever but not to the preset RPM. We took it to the dealer when it had 200 hrs on it and they kept it for a week and said they found nothing wrong with it (GRRRRR) Any help is appreciated, Chris

 

[JD4440]

Anyone ?

 

[Tazza]

Anyone ?

Never worked on a JD, it could be so many things. Spun big end bearing will make a knocking sound, fuel detonating can make a knock too. As you say the RPM changes, you may want to check the injectors just to be sure they are not dripping. The govenor should hold the RPM pretty well rite though.
Sorry, thats all i got without seeing it....

 

[dozer]

Never worked on a JD, it could be so many things. Spun big end bearing will make a knocking sound, fuel detonating can make a knock too. As you say the RPM changes, you may want to check the injectors just to be sure they are not dripping. The govenor should hold the RPM pretty well rite though.
Sorry, thats all i got without seeing it....

mine does this as well but not the knocking so much as the random idle jumps. I await any more ideas. DOZER

 

[JD4440]

Never worked on a JD, it could be so many things. Spun big end bearing will make a knocking sound, fuel detonating can make a knock too. As you say the RPM changes, you may want to check the injectors just to be sure they are not dripping. The govenor should hold the RPM pretty well rite though.
Sorry, thats all i got without seeing it....

What do you mean by the injectors dripping? not shutting off between cycles? The rpm jump is major; like 1/4 or 1/3 of the trottle lever travel to return to the previous rpm.

 

[Tazza]

What do you mean by the injectors dripping? not shutting off between cycles? The rpm jump is major; like 1/4 or 1/3 of the trottle lever travel to return to the previous rpm.

With a fuel injector, you have high pressure diesel that goes to it, the nozzle lifts up and squirts the fuel out. If its dirty or has something stuck in the seat it will not spray correctly or not close. Fuel can then form droplets and drop fuel out and not spray it in a mist for ignition. This fuel can burn holes in the pistons. But it usually does cause power loss and shaking of the engine due to that cylinder not firing correctly and black smoke.

 

[skidsteer.ca]

With a fuel injector, you have high pressure diesel that goes to it, the nozzle lifts up and squirts the fuel out. If its dirty or has something stuck in the seat it will not spray correctly or not close. Fuel can then form droplets and drop fuel out and not spray it in a mist for ignition. This fuel can burn holes in the pistons. But it usually does cause power loss and shaking of the engine due to that cylinder not firing correctly and black smoke.

Not sure how the rpm could vary so much. If its not in the throttle linkage about the only other thing that comes to mind is the governor in the the injection pump is gong south. Injection pumps are generally not worked on by "mere mortals" but rather repaired by he gods at a injection pump shop for a ungodly price.
If you shoot me a email I can sent you some info from the manual
ken at skidsteer.ca at = @ of course
Ken

 

[yellowstonepart]

Edited: was an add, not on topic

 

[JD4440]

This condition worsened to the point I had to take it to Deere. It developed a problem of the control levers going full forward and choking the engine when you set the brake. That along with the knock getting so bad 2-3 other employee's came to me wanting to know what the deal was. Took it to Tri-Green Equipment in Hendersonville, TN. Somewhere on here I was told maybe the hydro needed to be centered so I took it in. Turns out I was lucky in that they said all they did was replace the damper cylinders on the control levers and it's good now. Doesn't even try to walk now when the brake is set. As for the knock: Service manager said he smelled diesel as I unloaded it. The injectors were pulled and sent to a diesel shop where they were deemed bad due to fuel contamination. All new reman injectors, filter, adjusting the control pedals, checking the glow plugs, 2 keys and some JD fuel conditioner and $1114 later I have a skid steer that runs better than the day I brought it home new. I'd definitely recommend Tri-Green to someone; I'm even gonna pull off the Consumer Tractor decals and put theirs on haha.

 

[skidsteer.ca]

This condition worsened to the point I had to take it to Deere. It developed a problem of the control levers going full forward and choking the engine when you set the brake. That along with the knock getting so bad 2-3 other employee's came to me wanting to know what the deal was. Took it to Tri-Green Equipment in Hendersonville, TN. Somewhere on here I was told maybe the hydro needed to be centered so I took it in. Turns out I was lucky in that they said all they did was replace the damper cylinders on the control levers and it's good now. Doesn't even try to walk now when the brake is set. As for the knock: Service manager said he smelled diesel as I unloaded it. The injectors were pulled and sent to a diesel shop where they were deemed bad due to fuel contamination. All new reman injectors, filter, adjusting the control pedals, checking the glow plugs, 2 keys and some JD fuel conditioner and $1114 later I have a skid steer that runs better than the day I brought it home new. I'd definitely recommend Tri-Green to someone; I'm even gonna pull off the Consumer Tractor decals and put theirs on haha.

Thanks for the update, it is good to hear the solution to these strange problems.
Skidsteer.ca