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Thread: tightening fan belt on caterpillar 12 grader

  1. #1
    Join Date
    Dec 2010
    Location
    Deshler Nebraska
    Posts
    126

    Confused tightening fan belt on caterpillar 12 grader

    Hi guys i am working on servicing my cat 12 and the fan belt is awfully loose. In my operators manual it says 9/16 of play and I have an 1 1/2 of play in the belt between the pulleys. I have removed the bolts and the locks as instructed in my manual and have tried to turn the locking pulley but it has been a long time since it has been adjusted and I can not budge it. I thought about using a block of wood and a shot hammer so i do not nick or tear the pulley up using a bar and hammer trying to spin it towards the radiator. Any one else ever had this problem and what do you suggest. Thanks in advance again guys.
    Cat D6C 76A2045
    Cat No. 12 8T15616

    Caterpillar-Dodge-Lincoln-Stihl-Echo-Craftsman

  2. #2
    Join Date
    Mar 2009
    Location
    yuba city,california
    Posts
    1,338

    Default

    I’ve heated the adjuster and drenched it well with loose juice; you could “gingerly” use an air hammer on very low pressure setting and a suitable shank. It’s possible your pulley is worn and you could be out of adjustment also. Be careful and good luck. JM

  3. #3
    Join Date
    Dec 2010
    Location
    Deshler Nebraska
    Posts
    126

    Default

    Hey JM thanks for the response. I will give it a try. I did a little more looking back on here and found a few other posts to about this on a D6 9U and I didn't think about it but they have the same method of adjustment, duh on my part. Ill see what I can do and report back. Thanks again sir.
    Cat D6C 76A2045
    Cat No. 12 8T15616

    Caterpillar-Dodge-Lincoln-Stihl-Echo-Craftsman

  4. #4
    Join Date
    Nov 2006
    Location
    Gold Coast, Queensland, Australia
    Posts
    4,901

    Default Tool For Job.

    Hi, D2Cody.
    Put the locking tabs back in their slots with the long ends facing out and turn the screws down so that they are finger tight, no more than that, 'cos those adjuster nuts are designed so the screws clamp the nut down onto the threads as well holding the locking tabs in place. Then try tapping gently against the locking tabs in their slots with BIGGG MOBBBBS of loose juice being applied well beforehand.


    Just my 0.02.
    You have a wonderful day. Best wishes.

    Deas Plant.

  5. #5
    Join Date
    Nov 2006
    Location
    Faunsdale, AL USA
    Posts
    4,139

    Default

    The older ones have webs or ribs cast into the rear of the adjustable pulley. These are perfect to jam a short rod, deep socket or short extension between a web and bolt heads etc on the water pump to hold that half of the sheave stationary while pushing or pulling the fan blade to turn the front half.

    I have also heated the rear flange when I couldn't move it any other way. Doesn't do the belt any good, but frequently it's time to get a new one to have on hand when you have to tighten the old one a lot. Tightening a new belt is par for the course, just something to be expected, but tightening an old one is frequently the first step to replacing it!

    The new designs are made for a pin spanner to engage in the holes where the locking tab bolts are removed. There's not much else on the back side of those. I have seen them which were adjusted using a cold chisel!
    D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time

  6. #6
    Join Date
    Nov 2006
    Location
    Corralitos, Ca.
    Posts
    14,915

    Default

    The correct tool for adjusting the pulley is an adjustable pin spanner wrench that fits the recessed holes once the locking tabs and bolts are removed.

  7. #7
    Join Date
    Dec 2010
    Location
    Deshler Nebraska
    Posts
    126

    Default

    Thanks for all of the replies guys I really appreciate it. In about an hours time from when I first posted I finally got the pulley to come free with a little PB and Wd. Then with a piece of round stock from the shop, a short 2 x 4 and a small ball peen I lightly spun the pulley and got her adjusted to recommended tension. I think the threads just had enough rust and grime in them that it was just needing oil and worked back and forth. I will be keeping this thing in operating order from now on so I don't have to deal with that nightmare again lol. But thanks again for the help I would be pretty lost without all the help all the time.
    Cat D6C 76A2045
    Cat No. 12 8T15616

    Caterpillar-Dodge-Lincoln-Stihl-Echo-Craftsman

  8. #8
    Join Date
    Mar 2015
    Location
    north idaho
    Posts
    635

    Default

    Glad you got it working. One thing I will add is when I did my 112 once I got it moving I took the fan belt off and spun the hub back and forth until I could spin it by hand. Then I cleaned the threads and painted them with antisieze. Keeps everything nice and you don't have to fight it next time

  9. #9
    Join Date
    Dec 2010
    Location
    Deshler Nebraska
    Posts
    126

    Default

    Thanks Gary. I really like that idea, I will give that a try.
    Cat D6C 76A2045
    Cat No. 12 8T15616

    Caterpillar-Dodge-Lincoln-Stihl-Echo-Craftsman

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