JD 6.8 Power Tech Engine

[loggerman]

Hey guys I'm not in the construction business but thought I could get some ideas here anyway. I have a 2000 JD skidder with a 6.8 Power Tech Engine, the engine started vibrating really bad today, it runs well, idles well, no knocking at all, engine mounts are good ect. My conclusion was a poor vibration dampner, does that make sense? any suggestions would be greatly appreciated. Merry Christmas Folks!

[Wulf]

Hi loggerman... when does the vibration occur? At what RPM and when in neutral or when traveling. How many hours on the engine? How about the output end of the engine such as drive shafts etc?

Engine damper troubles are pretty hard to diagnose other than inspecting them for external damage or removing them for inspection. Once removed a simple test you can use is to roll the damper on a flat surface and see where it stops, if it keeps stopping in the same place its defective, Deere may have a more specific method so I would check with them, also there may be a service news or product improvement out on the component that they may tell you about.

You are right to be concerned... a defective harmonic damper can cause major engine and drive train failure and many specialists always replace them when it comes to rebuilding an engine!

[loggerman]

Wulf, thanks for the reply, the engine has close to 7000hrs on it, the vibration is throughout the entire RPM range, it occurs if the machine is in neutral or not. Other details: 8 speed power shift transmission, continues live winch, it does not appear to be a drive line issue.

[Wulf]

Well it sounds like the damper. Depending on the replacement cost you may want to get your dealer to check it out prior to replacement or just let them handle the job.

[Steve Frazier]

You might want to check that the flywheel is tight too.

A flat cylinder would cause engine vibration as well.

[Diagonal Brace]

I was looking through my JD operation and maintenance manual and it says to change the vibration damper (6 cylinder engines only) every 4500 hours or 60 months. It also gives a method for testing (grab outer part of dampener and twist) and also for checking runout.

[Countryboy]

Welcome to HEF Diagonal Brace! :drinkup