John Deere 710 balance shafts

JD710

New member
I have recently rebuild the engine on my John Deere 710 4 cyl diesel engine and when I took off the front timing cover I noticed that one of the lower balance shaft gears were not connected to any of the timing gears so it would not be turning. Is this possible or did it not get put in at sometime?
 

jd110

Member
Sounds like someone forgot to install the lower idler gear at some time. The left balancer runs off of the oil pump gear. The right one has it's own idler. Did the engine vibrate? Is the stub shaft there that the idler should fit onto?
 

JD710

New member
hard to tell if a diesel engine is vibrating as it is old. no stub shaft installed, only the balance shaft and gear on the end inside the timing cover area. Should I hook up this balance shaft? Will it hurt anything?
 

jd110

Member
Personally, I would want it connected. Extra vibration is no good for it. I would think that one shaft spinning without the other might be more harmful than neither one spinning. As long as the shafts are in place and don't have too much bearing clearance, the oil pressure should be ok. I have heard of people removing the shafts and blocking the oil holes after the bearings fail and damage the block around the bearing bores. I wouldn't recommend it, but it has been done.
 

JD710

New member
Thanks for your reply and advice. I feel the same way and will hookup the other balance shaft, figure it can't hurt anything. I will have to install the bearing and lower idle gear. I have it all apart now changing the crankshaft and lower bearings so this is the time to do it.
 

danny

New member
I have a 2630 JD the engine was rebuilt a year or so before I got it I dot think they replaced the blancer bushing . Because the oil pressure gets low at idle when warm can these bushings be replaced without removing the engine ? Also do they need to be line bored thanks for any info.
 

jd110

Member
The engine does need to be removed to properly install the bushings. The bushings don't need align boring if installed properly with the correct tools. If the bushings are worn, chances are good that the shafts are worn also. The timing cover nees to be removed to access the front and center bushings. The flywheel housing needs to be removed to install the rear ones.
 

danny

New member
Thank you for the information, I have the JD manual on this tractor but it does not go into the shafts very deep. Thanks, Danny Chavez.
 
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