Can we talk about the Detroit Bull Gear?

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Hanadarko, Mar 27, 2012.

  1. 66truck

    66truck Light Load Member

    Nov 7, 2008
    Ok , this helps me , I know my water pump is driven off the bull gear,so its the old style, its been checked and has no play in it, but with the miles and all the talk about this part it makes me a little nervous. Oh , the serial on my engine is 06R0702846 model 6067BK60

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  3. GrapeApe

    GrapeApe Road Train Member

    Jan 7, 2013
    With that many miles, I'd schedule it to be done ASAP. If you are planning on attempting it yourself, I can email you a service manual. You will need a front seal installer tool, a good torque wrench and a dial indicator. I also recommend a new cam thrust seal and perimeter seal while they're much easier to get to with the cover off.

    If you cannot afford the down time, I would not recommend doing it yourself.
  4. heavyhaulerss

    heavyhaulerss Road Train Member

    Dec 23, 2009
    Well ya don't have to talk about me om an open forum. :biggrin_2559:
  5. 66truck

    66truck Light Load Member

    Nov 7, 2008
    No, thats not something I want to tackle on my own, I have a shop with a good mechanic I use for the more difficult jobs. Thank you and catmechanic07 for all the info, very helpfull.

  6. gator21

    gator21 Light Load Member

    Dec 4, 2011
    Norwich NY
    ok guys...I've just read all posts on this deal.i have a 2002 international w/12.7 dd.1.3 million on trk,300,000 on the inframe.i just bought it 3 months ago.i have all the records from the original was stated at the top of this thread,the bull gear was not touched.nor was the harmonic balancer.i really want(need) to have pdi re-program this slug so it will run good.however,im afraid of the bullgear gods frowning down apon my truck after its been peaked & tweaked.several friends and mechanics have stated "get that thing changed before you have to replace the whole motor".penn d.d. in Pa.says parts are 600$ plus 22hrs labor.d.d. in NY. says parts are 2000.$ plus 33hrs labor @106.00per hr. either way im lookin @ 5 grand plus. :biggrin_2552: Now, I called Pittsburgh power and they said with great confidence,$3700.complete...also diesel power in IN.also said around 3500. So some of you are sayin that if its the newer style have it checked and advise,if its the older style GET IT OUTTA THERE ASAP? pitts power says its a 16hr job.How badly I want to get screwed is a direct result of where im sitting at that moment.would any of you pump up the power if your trk had 1.3mil on it and the bull gear was inspected to be ok?
  7. Cowpie1

    Cowpie1 Road Train Member

    Nov 25, 2008
    Kellogg, IA
    Reviving this thread somewhat. You can get great reman bull gear assemblies at a considerably lower price than new. These folks are top notch.....

    No reason to put off doing a bull gear assembly replacement. A bull gear is the classic example of the true meaning of "preventative maintenance". Airlines don't wait for engines to come apart in the air before replacing. They know the average life expectancy out of their components and replace them on a schedule. That is the true meaning of "preventative maintenance". The average life out of a Detroit bull gear assembly has been shown to be just over 800,000 miles. This is why most experts in the industry, and my Detroit Owners Manual, says replace the bull gear assembly at 800,000 miles. Considering the cost if something goes wrong, compared to the cost of just replacing it on a scheduled basis, it seems like a no brainer.
    tommymonza Thanks this.
  8. leewayg

    leewayg Bobtail Member

    Sep 2, 2015
    My husband is a ex military mech. Been awhile since he did one and he said the last one he did was a Cummings. We are way past due for this as we have rebuilt the motor 2 times and never the bull gear. Would u mind send us your manual?
  9. Prevatt315

    Prevatt315 Bobtail Member

    Mar 20, 2015
    I am having my 12.7 DDEC 2 bullgear replaced right now. I bought the truck not running but knew this was the problem. When the bearing went, it took out teeth on the bull gear and the idler gear. No damage to the front cover or inside front of the engine. Also, the head was not damaged. I felt that was lucky. From what I read in the research before and after buying the truck, a gear going usually takes out the front of the engine. I'm not doing the work myself. While my mechanic is in there, I am having the cam bearings replaced. Would suggest you do the same if you either have high miles or do not know the history of the truck, like as in my case. The hard work is done so getting the cam out is not labor intensive. And, comparatively speaking, bearings are cheap. I am planning to get the old girl back on the road and healthy. After this, we should good for another 750,000 miles. It is a pain and expensive but worth the peace of mind. Your mileage may vary. Red.
    Trugo Thanks this.
  10. krazman

    krazman Light Load Member

    Dec 11, 2007
    So I was looking at a 2007 columbia 120 with 12.7 . 550k. What I get from reading this thread is it is already in need of overhaul or at least replacing them gears .
    Now I am thinking if do not want to buy it. Seems detroit says replace at 800k but since I would be just starting out new business and broke from buying truck , authority etc. . . .
    Last edited: Jun 23, 2016
  11. catwrench55

    catwrench55 Light Load Member

    Jan 5, 2015
    Ddec 5 had a more reliable compact gear train.
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