torquing main bearing caps

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by stonefly4, Jan 18, 2020.

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  1. stonefly4

    stonefly4 Light Load Member

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    I need to replace the bearings on my 12.7 series 60.

    I don't have a big torque wrench and I plan to, hope to, torque down the main bearing caps using an alternative method.

    Years ago, a mechanic with a lot of experience rebuilding Detroits told me how he torqued the bolts, and it sounded like good advice, but I forget important details.

    He used a smaller torque wrench to tighten to 100 or 200 ft. lbs., I forget which, and then he turned the bolts one or two more flats, again I forget which. He told me that is the way he always did it and it never failed.

    I saw a youtube video where the bolt gets torqued to 100 ft. lbs., and then turned one flat. Done. But that was on a Caterpillar engine and the torque specs might be different.

    Anybody here have any experience torquing Detroit mains using this method?
     
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  2. Rideandrepair

    Rideandrepair Road Train Member

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    Go buy a torque wrench, they’re not that expensive. You’ll use it more than you think. Even a cheap one is better than nothing. My Harbor Freight wrench checked out accurate against my Uncles expensive one. Just store it with cap loose, no load on it. Proper torque values should be easy to find, I’ll look them up if needed, not worth the risk.
     
  3. Dino soar

    Dino soar Road Train Member

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    Please do yourself a favor.

    Buy the right torque wrench that you need. Harbor Freight has a torque wrench that goes up to 300 foot pounds that's not expensive.

    If you do not torque them tight enough and those bolts come loose your engine is done.

    If you over tighten them and you stretch the studs they can break and then your engine is done.

    That is one thing that you need to have the exact correct perfect torque with a torque wrench.
     
  4. stonefly4

    stonefly4 Light Load Member

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    I hear ya, but it's not only a matter of expense. It's tight under there, and I ain't young anymore, and also, I don't think I could do it by myself. In fact I'm sure I couldn't.

    From what I have gathered, the method I described, of torquing to a lower value, and then turning the bolt a fixed number of degrees, is a tried and true method of torquing.

    The cam bolt on a series 60 is properly torqued in this manner.

    I'd sure like to know that I could crawl under my engine with an impact wrench and in a few minutes have all the main bearing caps torqued down.

    But I need the details.
     
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  5. Rideandrepair

    Rideandrepair Road Train Member

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    I see what you mean, torque values are 347-391 ft lbs. I had no idea they were that high. That’s a big torque wrench!! Lol. Good Luck, Maybe you can rent one?
     
  6. stonefly4

    stonefly4 Light Load Member

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    It's a big torque wrench and it's a lot of work. The fellow who long ago told me his method was no dummy. He was experienced. I wish I remembered the details.
     
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  7. Dino soar

    Dino soar Road Train Member

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    EBay used to have a torque wrench that was 600 foot-pounds that was not that expensive. You can use that for your lug nuts also.

    If you can't do it hire somebody to crawl underneath and do it.

    It's not hard to get a 600 pound torque wrench to click on 400 lb. It is easier to torque it with a regular torque wrench than attempt to go an extra turn or however far with a pipe or whatever.

    The method that you are talking about torquing to a certain torque and then going an additional distance is something that is only done if the engineers tell you to do that. Otherwise you need the actual torque wrench.

    If I knew somebody torqued my bearings like that, I would not be able to sleep at night and I would be terrified every time I started it and every minute I was going down the road.

    Whatever it cost you whatever the aggravation is, it is worth it to know your engine is not going to come apart.
     
  8. stonefly4

    stonefly4 Light Load Member

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    That's why I started this topic. I've already decided which method I want to use. I only need some details.
     
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  9. Michael 247

    Michael 247 Light Load Member

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    Can you use a 1/2 in torque wrench and torque multiplier tool ??
     
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  10. Rideandrepair

    Rideandrepair Road Train Member

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    The manual I have online doesn’t mention a torqu/ degree method. I torqued flywheel that way, with my big wrench. I forget the lbs. but it was 60 degrees extra after that. On One flat on a 6 sided bolt. Recently saw a Torque wrench with the degrees guage on it also. They make torque multipliers, that are kin to an extension w/ a gear in it. They’re expensive though, but will make a set torque wrench, x 2. Don’t know how accurate they are though.
     
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