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Discussion Starter #1
Have a 9560 Sidehill and when the engine is running, it has got a funny noise I know it is hard to explain or diagnose with out being there in person. I was wondering if it was somthing common. It has a 6.8L 24 valve engine. It sounds fine when it idles but then the sound changes pitch off and on with really no consistancy almost like a small load is put on it or like a slight speed up. It dosn't sound like a miss or really run rough. It does the same thing at mid idle. Didn't try it at high idle. Didn't notice it yesterday when I had separator and feederhouse running. That is the best way I can describe it. No codes show up either. Won't really be able to run the maching again untill I get the other work done and get it out of the shop. Didn't know if on these engines that there needs a good load on it to make this go away. Any help would be great. Thanks
 

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Are you sure you are not hearing the pilot injection? Also the 6.8 have a wierd front gear train noise to them. Almost like a pinging noise to them.
 

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Discussion Starter #3
Pilot injection? Could you tell me a little about that please, and what it consists of. It isn't really a pinging noise. Almost like it surges then quits, then surges then quits like if a small load was put on it.
 

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Here is a DTAC case describing pilot injection:

Solution Number: 69498

Solution Summary: 4045, 6068, 6081, 6090, 6125 6135 Pilot Injection cycles cause diesel rattle or rap

Publication Date: Feb 4 2009


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**Paper copies of solutions may not be the most current solutions**

Complaint or Symptom :
The engine runs quiet at startup and then develops a diesel knock, rattle, miss, diesel ping or flutter.

Problem or Situation :
Tier 1 & Tier 2 engines:
The Tier 1 and Tier 2 engines (4045, 6068, 6081, 6125 engine models) with HPCR fuel injection system have pilot injection when they are started. Pilot injection acts as a pre-injection to aid in combustion during cold-start conditions, thereby reducing white smoke at startup.

The engine will sound different when the pilot injection switches from on to off.

Technicians have described the transition from pilot injection as sounding like a rattle, miss, knock, or ping.

For tractors, an additional variable was added after reprogramming for the PIP 03RW281. If the engine ever drops below 750 rpm, pilot injection will turn on. This may be noticed when starting from a stop at low idle. If pilot injection turns on under the 750 rpm and it is objectionable, you can adjust the default starting gear to a lower selection on your tractor.

Pilot injection is controlled by three variables:

Time

Coolant Temperature

Load

Pilot will turn off when one of the three variables is met:

Pilot turns off when the time from start up exceeds 10 minutes.

Pilot turns off when the coolant temperature exceeds 167°F or 75°C.

Pilot turns off once a load is applied to the engine.

Tier 3 Engines:
The Tier 3 engines (4045, 6068, 6090 & 6135 engine models) pilot injection option is always active. On Tier 3 engines the pilot injection will cycle on & off whenever the engine is operating. The customer will most often notice a flutter in the engine at low idle without a load.

Solution :
This is a normal operation of the engine. No repairs should be made. This pilot fuel function is utilized to reduce white smoke during start/warm-up.

To verify if pilot is on or off, use Service Advisor or DST and refer to the Pilot Injection parameter in the Data List. The display will say either "On" or "Off."

Additional Information :
Ping, Rattle, Rap, Pilot, Tier
 

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Discussion Starter #5
Pilot injection is what I was hearing. I believe is is a tier 2 engine. It kept doing it at idle but when I put a slight load on it such as swinging in or out the unloading auger it quit. It still did it when water temp was above 167 degrees (address at cornerpost display). But I drove down the road and up some good hills and temp got to say 180 I ran it a low idle and didn't hear it then. I think I was just being over cautious and not to familiar with high pressure common rail systems. By chance the pilot injection don't quit on a tier 1 or 2 engine when all 3 variables are met, what would have to be done? Thanks for your help.
 
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