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Thread: Questions for rebuilding D8 14A pony engine

  1. #1
    Join Date
    Jun 2012
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    Poway, CA
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    1,885

    Default Questions for rebuilding D8 14A pony engine

    I decided to tear into the pony engine on the 14A to see what it would take to get it back in running condition vs just sticking a running pony in from another tractor. That way the tractor is maintained I believe as it always was without any substitutions made to it.

    I spent the last several days getting it out and torn down. I was able to get the pistons pressed out of the block today and the retired CAT tech from Hawthorne Machinery here in San Diego who was helping me said those were the toughest pistons he ever pressed out. It looks like cleaning and honing will get them back in order. He then measured the main bearings and found the crankshaft has been turned once so now I need to have it turned again to end up 0.030 under. The rod bearings are already turned to 0.020 under but the crank can be polished and he says new bearings the same size as the old can go back in.

    I have not yet checked with CAT on parts. I think they will still have this stuff. Those who have done this before I need to ask is that the way to go or should I try Perfect Circle or some other supplier? Who else can supply these bearings? Obviously cost is a consideration in that this is a hobby tractor.

    Any other "what to watch for" or "lessons learned" would be great to know. Thanks in advance for helpful comments that are always available here on our great forum.

    By the way, those who attend the National Show banquet at Santa Margarita this spring will hear "Scotty", the man helping me today, give a presentation on his adventures in Antarctica working with the LGP D8s including "Mary Ann" whose story is discussed on here fairly often. I would most likely not have tackled this project were it not for his willingness to help me do this!

    JanM

    PS - Chum Duffy- note I am finally getting to this pony engine!!!!

  2. #2
    Join Date
    Nov 2006
    Location
    Pittsford NY
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    4,946

    Default

    Good deal Jan. It's much more satisfying I think to fix something that's already there than to swap in new parts. The pony on my 3J has a cracked block but I had it brazed and have been running it with stop leak and it just about has stopped leaking. Feels a lot better than junking that block. I look forward to seeing that pony start and idle! : )
    FYI - I just priced the full size range of bearings for the 5U pony and from Cat they ran between 60 and 100, so a pair of mains would have run $160-ish. Yours might be a bit more than that being a bigger engine. Do you have two-bearing mains?
    Cheers,
    Neil.

  3. #3
    Join Date
    Nov 2006
    Location
    Corralitos, Ca.
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    15,408

    Default

    Gather up your part numbers and go shopping. I'd start with Florin Tractor then move on to Machinery Trader and Off Road Equipment.

  4. #4
    Join Date
    Dec 2006
    Location
    victoria australia
    Posts
    3,522

    Default Main Bearing Spacer Washers

    Hi Jan,
    when you remove the pony sump check for and keep aside and wired together with a tag to identify them for refitting at the time of assembly the 4 - 2B4219 spacer washers on the main studs that prevent crushing of the main bearings onto the pony crank main bearing journals.

    Have in the past had to fit several of these after clients rebuilt their own ponies and neglected to refit the spacers.
    The clients mechanics had luckily found their ponies tight to turn and embarrassingly had the Dealer check further.

    As I do not have the relevant engine SRB, the scans below of different model ponies should show what I speak of.
    Cheers,
    Eddie B.
    Attached Images Attached Images

  5. #5
    Join Date
    Sep 2009
    Location
    Asotin, Wa
    Posts
    2,167

    Default

    Jan, don't rule out your local Cat dealer for parts. I've been rebuilding an RD7 starting engine, I was pleasantly surprised by how many peices Cat still had for such an old timer. Really wasn't to pricey either. What Cat couldn't get me Dana at Florin tractor could. I'm just about finished with it.

    Bruce P
    Holt 45 power unit, Two Ton, Sixty (2), Diesel 40, No.11 AutoPatrol, 4G D4, 9U D6, 17R D6C, 9G D7, 7M D7, DW20.

  6. #6
    Join Date
    Jun 2012
    Location
    Poway, CA
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    Default

    Quote Originally Posted by edb View Post
    Hi Jan,
    when you remove the pony sump check for and keep aside and wired together with a tag to identify them for refitting at the time of assembly the 4 - 2B4219 spacer washers on the main studs that prevent crushing of the main bearings onto the pony crank main bearing journals.

    Have in the past had to fit several of these after clients rebuilt their own ponies and neglected to refit the spacers.
    The clients mechanics had luckily found their ponies tight to turn and embarrassingly had the Dealer check further.

    As I do not have the relevant engine SRB, the scans below of different model ponies should show what I speak of.
    Cheers,
    Eddie B.
    Eddie,

    I did read about the washers in the book just before separating the two pieces but it was a bit of a fight to get them apart so the washers eluded me in the process. They are probably laying on the garage floor where it all happened and I will be sure to put them back when the time comes. Thanks for the heads-up.

    Bruce P- Yes I went to CAT today and they do have a lot of what I need but we still got some "discontinued" on the computer screen.

    JanM

  7. #7
    Join Date
    Apr 2011
    Location
    Smethport in the Northwestern part of PA
    Posts
    162

    Default Atta boy Jan!!!...

    Quote Originally Posted by janmeermans View Post

    PS - Chum Duffy- note I am finally getting to this pony engine!!!!
    Very Cool!!!.....

  8. #8
    Join Date
    Jan 2017
    Location
    Southeast Texas
    Posts
    30

    Default

    What is the displacement on these pony motors?
    SE Tx
    D6C 10K

  9. #9
    Join Date
    Jun 2012
    Location
    Poway, CA
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    1,885

    Default Getting things ready to re-assemble

    Quote Originally Posted by janmeermans View Post
    Eddie,

    I did read about the washers in the book just before separating the two pieces but it was a bit of a fight to get them apart so the washers eluded me in the process. They are probably laying on the garage floor where it all happened and I will be sure to put them back when the time comes. Thanks for the heads-up.

    Bruce P- Yes I went to CAT today and they do have a lot of what I need but we still got some "discontinued" on the computer screen.

    JanM
    It has been awhile since this project started and now an update. I ended up having the cylinders line-bored to 0.040 over in order to get smooth cylinder walls again. When I picked up the block today from the re-builders, only 3 spacers showed up with the studs. I have found many spacers showing up in Machinery Trader Parts so no problem getting the replacement. The crankshaft continues in the chrome vat still building up thickness so that is the only thing still not here. I have gathered gaskets, seals, pistons, rings and other needed items mostly from two sources listed on Machinery Trader- F P Smith and CIS in Tn.

    Maybe within the month I will have it all back together again.

    JanM

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