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D8H Leaking front main seal

Discussion in 'Dozers' started by farmerlund, Jul 3, 2016.

  1. farmerlund

    farmerlund Senior Member

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    D8H SN 46A31476. So I think the front crankshaft seal started leaking fairly bad. I took the front bottom skid plate off and it looks like that's where it is coming from, kind of hard to tell with the fan and pulleys throwing oil every where. It seams sort of odd that it could be dry than start leaking that bad so quick. Am I missing something? The dampener is not loose, every thing seems ok that way. I did notice there is a little end play in the whole crankshaft. does anyone know what that amount should be? I could put a dial indicator on it and check it. This is a good running engine with very low oil consumption and no other leaks.

    It looks like the radiator has to come out to get dampener off, how about the front engine mount? does it have to come off too or can it stay? Any help from someone experienced with these old beasts would be greatly appreciated.

    Thanks, steve
     
  2. nicky 68a

    nicky 68a Senior Member

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    Rad out.
    I'm fairly sure engine mount stays put.
    This is a good time to replace all 3 pulleys and fit new belts.It's not as expensive as you think allthough I use Genuine Cat belts.
    You will be surprised what difference new,matching pulleys and belts make.
    The crank seal is easy and cheap to do do.You can buy a metal sleave to fit on the end of a worn crank seal path and an undersize seal.
    Tony Coates can advise (Chicago Raw hide???)
    You can also bung 2 standard Cat seals in there in the hope it will hold back the oil.
    Your rad will need to be out to give it a proper steam cleaning,if you are feeling generous,it's only another hour to remove both coolers to clean them up.
    The difference will be amazing.
    Poker new tranny pump and suction line on........and you have a new D8!!! ha ha.
     
  3. RBMcCloskey

    RBMcCloskey Senior Member

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    Thank you, excellent advise and fix.
     
  4. GregsHD

    GregsHD Senior Member

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    I would also check your crankcase breather and pipe, make sure it's not blocked up and causing excessive crankcase pressure! The crankshaft end play should be somewhere between .010" and .020"
    You wouldn't want to see much more than .035"
     
    Last edited: Jul 3, 2016
  5. farmerlund

    farmerlund Senior Member

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    Thanks Nicky for the fix list, I was thinking it was about like that. Planed on getting belts. Yep the rad will definitely need a good cleaning.

    I was thinking about the breather system last night and will check it out. thanks for the end play measurements GregsHD.
     
  6. tctractors

    tctractors Senior Member

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    The front Crank pulley will most probably need pressing off, there is pulling threads in the taper section to sort this event, they can be any size from 1/2" to 3/4" as they pull out the threads easily as the loading can be high to effect removal, the crank seal will be common to find with a sleeve fitted to the crank, I have a simple tool that crimps a line into this band upsetting its grip and spins it out in moments,the seal and sleeve should all be pressed home as one.
    tctractors.
     
  7. RonG

    RonG Charter Member

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    farmerlund,you have practically hired the repair done for you.If you have any more questions and can catch tctractors in time it don't even cost a dime to get your answer.Lets get those radials singing.Ron G
     
  8. farmerlund

    farmerlund Senior Member

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    Thanks TC, I cleaned around the crank pulley this AM and found the treaded holes for pulling it off the crank. Also checked out the breather filter and tube was nice and clean so I guess the seal just craped out. Should get it apart on Tuesday and get parts ordered.

    I did check the end play and it is .024-.025. Is there a torque spec for the big bolt holding the dampener on?

    I wish it was that easy RonG, ha. its hard to be working on a dozer when could be flying that's for sure.
     
  9. DPete

    DPete Senior Member

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    I think I have a damper puller made from a front U-joint flange for an early 235 hp 8H, ( not sure the 270 hp is the same) I can post a pic or even send it to you if you have trouble getting it off. Big flanged bolt needs to be tight, trouble is holding the engine from turning, I think we made a socket and welded on a bar to strike with a hammer to tighten. We had one get loose and ruin the crankshaft taper trying to tighten with a wrench. If it's the same as a low horse the small 15/16" lock bolt is left hand thread.
     
    Last edited: Jul 4, 2016
  10. GregsHD

    GregsHD Senior Member

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    600ft lbs for the damper bolt, smack it with a big hammer then torque it again.
     
  11. farmerlund

    farmerlund Senior Member

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    Worked on getting at the front main seal today. Things went pretty well, took some grunting to get the dampener to pop off. The seal was pretty wore, and the speedy sleeve was almost cut in two. At least it is good to see the problem. Got parts ordered, so we can get it back together end of the week. Thanks to the guys for the tips and specs, made it go smoother. :drinkup


    All cleaned up and ready to go back together. 002.jpg
     
  12. RBMcCloskey

    RBMcCloskey Senior Member

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    You tool sounds interesting, can you post a picture of it?
    Thanks,
    Bob
     
  13. tctractors

    tctractors Senior Member

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    RBM, firstly the kit to pull off the front Dampener is just a flat plate with bolts and a small service press cylinder, these hubs can take some removing? the tool I have for getting the sleeve off the crank is listed in the CAT tool chart, although the tool I use is a home made copy its just a square of tool steel with 2 sides ground smooth, the sharp hard edge cuts into the sleeve when the tool is twisted in the seal location, some times I have to put 2 knick's in the sleeve before the sleeve will spin out as I remove the tool, this takes only a few moments to do with NO damage to the crank or seal location, I think there is photo's in the shop talk Caterpillar Sprocket removal post, I would have removed the fan in the picture to check things past it as failed bolts and hub bearings are the common thing.
    tctractors
     
  14. nicky 68a

    nicky 68a Senior Member

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    Yes Farmer.
    Take the fan off as TC suggests to check the bearings and spacer .
    Those little keeper plates can come adrift allthough later ones have just one big nut that should behave itself.
    Your mounting brackets will have 3 5/8" bolts (on early 46A's)or 3 3/4" bolts on later tractors.
    Replace with new genuine Cat bolts.
    Your tractor looks nice and clean now with a decent looking undercarriage from what I can see from the pic.
     
  15. farmerlund

    farmerlund Senior Member

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    Hey TC and Nicky,

    I am going to check out the fan tomorrow and see what the bearings look like. do you normally just replace them or look and decide?

    Thanks for the suggestion.
     
  16. Nige

    Nige Senior Member

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    Personally if you've gone that far I wouldn't even look at them, simply replace. The replacement bearings/pulleys are not going to break the bank but a new radiator could do if that fan ever falls off ......
     
  17. kshansen

    kshansen Senior Member

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    I'll second that, the price of a couple bearings and pulleys compared to new radiator core or damage to engine from overheating is pennies. Besides 90% of the labor is already done!
     
  18. farmerlund

    farmerlund Senior Member

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    Worked on the getting the D8 going yesterday. I had to make a tool on the lathe for installing the sleeve and seal. it worked good. My worker did a great job straightening the rad fins, they were pretty flat in spots from years of use. We got every thing put back together and ran it for a short time so we could change oil.
    Still have to put some sheet metal back on, and few other things, but looks good so far. new 002.jpg new 003.jpg



    One thing I just noticed is my water pressure gauge, sits at the line between the first two blue colors. Even with the rad cap off and engine off. shouldn't it rest at the bottom or right side normally? I just cant remember. maybe it going bad. I know its not related to the oil leak but just some thing I just noticed.

    Thanks again for the Input guys.
     
  19. nicky 68a

    nicky 68a Senior Member

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    Farmerlund,that tractor will run a million times better now mate.
    The problem with your water pressure gauge is that you haven't blanked it off yet.
    Crimp the line tight without cutting it.
    That remedy has cured thousands of D8's over the years.
    If you have a pressure problem that warrants attention,
    You'll know about it soon enough without that gauge giving you sleepless nights!
     
  20. Nige

    Nige Senior Member

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    It's a wonder that radiator was getting any air flow at all through it with that percentage of fins twisted and/or plugged with oily debris.