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Bull gear on mp8 engines

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Leased on with a guy's company; he has a 12 model Volvo that the bull gear bearing retainer backed off; I have a 12 model Chu & wondering how I would know if my truck falls under this same problem; & what I should do

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Double idler gear failures are not uncommon. Starting in 2010 the oil temperature was raised to 238 degrees and the hotter oil was causing the retainers to loosen, originally the retainers were installed with Loctite and not staked in place. After a rash of failures staking the retainers was put into production can't remember exactly when. There was a campaign to "pin" the retainers for a while, haven't done it in years, You could ask your dealer about it and see if they would be willing to do it for you. It's possible the gear in your engine has a staked retainer already.

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My dealer not going to do anything for me

wonder if VIN # could tell anything? 

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I can't help with the VIN, the pinning campaign was PI0785 and was issued in May 2102. You can check your trucks build date it's on the decal inside the drivers door jamb, you could also contact Mack to see if your truck was part of this campaign and whether it was already done. Another thing to look at is to see if a plug is installed in the top of the flywheel housing next to the crank sensor, the plug is put in after the pinning is done.

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Built 09/2011

I'll check with Mack & see what I can find out; also check for the plug

thanks for input

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It would be good to check  with them we have had a couple of these slip thru the pin campian cracks  it happens on MP ten as well, ( No campaign on these) if you have a clattering sound coming from your engine or your compressor comes loose you better ask why! or you may be out 20-30 grand. depending how catastrophic !

Edited by fjh

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On October 8, 2016 at 1:05 PM, Macktech689 said:

I can't help with the VIN, the pinning campaign was PI0785 and was issued in May 2102. You can check your trucks build date it's on the decal inside the drivers door jamb, you could also contact Mack to see if your truck was part of this campaign and whether it was already done. Another thing to look at is to see if a plug is installed in the top of the flywheel housing next to the crank sensor, the plug is put in after the pinning is done.

My truck was built in 11; looking at flywheel housing there's no plug; I've watched the u-tube video & my flywheel housing doesn't look exactly like 1 in video; the line they tell you to remove is in different spot; just wondering if this maybe a tell tell sign of updated engine; having to r&r clutch & was going to pull flywheel housing off to check bullgear; but didn't want too if it had updated gear; research with Mack has been no help; also was wondering if you could see with camera from top or bottom 

thanks for any help in this matter 

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There was no change to the flywheel housing when the staked idler gears were installed, removing the housing is no small job the back and bottom of the engine needs to come off. You can check the idler gear through the PTO cover at the top of the housing on the right side to see if it is loose, if it is you will also see where it's rubbing on the housing. The video you mentioned may have been of a MP-7. A good picture of the top of the housing would be helpful, a pic of the bottom won't show anything.

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2 minutes ago, Macktech689 said:

There was no change to the flywheel housing when the staked idler gears were installed, removing the housing is no small job the back and bottom of the engine needs to come off. You can check the idler gear through the PTO cover at the top of the housing on the right side to see if it is loose, if it is you will also see where it's rubbing on the housing. The video you mentioned may have been of a MP-7. A good picture of the top of the housing would be helpful, a pic of the bottom won't show anything.

Pulled flywheel housing off; nut seems to be tight; just going to stake it up; not much meat there to stake; everything looks good; can't find socket to check torque but can see the loctite & looks as nut hasn't moved 

any suggestions

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Drill it and drive a roll pin in! make sure your not to close one of the nut drive lugs  when you drill and it will be fine.close it back up

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