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How difficult is to inspect bull gear on 12.7?

I have 2002 12.7 pre-egr. Do you have to take a lot to apart to insect the bull gear? I have 400K miles on inframe which did the previous owner and don't know what condition is the bull gear, if he did it with the inframe or not. There is 1.3mil original miles. Is it a big deal to replace just the bull gear? Do you have to remove radiator? Or what else is good to do it along with, I know it should've been done with the inframe :-(((

Answer this question I have this problem too

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You can take the accessory drive off the right side of the engine and use a pry bar to see if there is any movement in and out. When it starts to develop a problem it gets further away from the engine.

There are other symptoms that can lead you to a problem with the bull gear too like hard starting because it is moving away from the engine. The SRS and TRS sensors have a harder time picking it up.

If your bull gear stats shedding metal you will find it in the oil. Detroit shops will know right away if it is from the bull gear.

Another place that collects shedding metal is the SRS ans TRS sensors. They are harder to remove though because they are behind the air compressor.

I lost my original bull gear when it starting coming apart. Luckily it was just starting to go and we found some pieces in the oil on an oil change.

Detroit recommends starting to check them at 750,000.........mine went at 746,000.

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That is good info., thanks. I knew it had something to do with the accessory drive.

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Your welcome, glad to help.

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If Detroit did the inflame they would have the records. all you need is the vin and a phone.

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I do not believe there is a way to visually inspect it. Probably need to call Detroit factory shop and ask them about this. If the bull gear starts to break down I'm sure there would be evidence in the spin on oil filter if you cut it open to inspect it.

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I thought I've heard the bull gear can be "inspected" by checking for movement in the accessory drive pulley. Sorry I can't elaborate on this more.

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I've heard that you will have filings on your drain plug if bull is going bad...

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the correct way to inspect the bull gear is to take right front cover off where pump fits and remove the plate. Then take a pry bar and wobble the gear inside the cover .if it has any and I mean any looseness have it replaced. The cover is on the front of the engine on the passenger side. it's suicide if te bull gear explodes.

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Front to back movement? Up and down movement? Any kind of movement?

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Any kind of in and out movement (much like checking the crankshaft bearings on a CAT engine).

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Jackie u have the correct way as far as I am concerned

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maek will be eternally grateful.
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