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Engine Rebuilding Nightmare

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BayouBlazer88, Aug 3, 2003.

  1. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    It seems the more I try to dig myself out of this hole, the deeper I go. I had just gotten my block back from the machine shop on thursday where they honed the cylinders (didn't bore them out which probably led to most of my problem), polished the crank, and installed new cam bearings. Yesterday I began to put everything back together starting with the crank. I put in the new main bearings, lubricated them well with a mixture of marvel oil and 10w-30 oil, and then torqued up the crank in 3 steps to 80 ft-lb just like the manual said. Spun the crank with my hand and it spun very smoothly. Now here's where the nightmare begins, when I start to put the pistons back in starting with #1, I used one of those ARP piston ring compressors for a 4.000" bore, aligned all the ring gaps according to the manual, lubricated the cylinder wall and the piston rings with the same Marvel mixture and began to tap the piston in gently with a wooden handle. For some reason it was very hard to push in but I eventually got it in all the way to the crank. Then I tried piston #2 which was ridiculously tight but I managed to push it through til it met the crank. I figured the piston just needed to be moved up and down a little with a few turns of the crank to lubricate it better, WRONG! The crank wouldn't turn even with a flywheel turning tool. So I talked to a friend of mine who knew someone that had rebuilt several engines and asked if this was normal, and he said hell no. So then I try to take the pistons back out which is only possible by hitting the rod bolts which I did and put a few notches in the crank journals in the process. I'm going to bring the whole thing back to the machine shop tomorrow and have them put in the pistons and do whatever is necessary to have this thing running right. So basically my first engine rebuild was a complete and utter failure and the only thing I have to show from it is a drained bank account. So does anyone have a clue as to why the pistons weren't sliding well? I used speed-pro cast piston rings that are supposed to be pre-gapped, unless for some reason they weren't. Other than that I have no clue what else could be wrong. And I appologize for the length of this post.
     
  2. TONYP

    TONYP 1/2 ton status

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    1- will the piston slid in without the rings?
    2-did you even put the rings in the check the gap? one min each to check...
     
  3. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    The pistons whould have slid in with just a few taps of a wooden handle. With all 8 pistons you should be able to turn the motor over with a breaker bar on the balancer. Are you sure you didn't get pistons that were .030 over bore?

    85K5 3/4ton,14bolt,10bolt,9"lift,35"boggers,16.5x14 welds, big horse 406SBC/700R4 /forums/images/graemlins/k5.gif /forums/images/graemlins/angryfire.gif
     
  4. Z3PR

    Z3PR Banned

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    [ QUOTE ]
    Are you sure you didn't get pistons that were .030 over bore?





    [/ QUOTE ] That's my thought also.
     
  5. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    to TONYP: No, I didn't try to slide them in without the rings nor did I pay much attention to the gap.

    to rjfguitar: I didn't buy new pistons, I'm reusing the old ones and they were all marked when I took them out so the same piston went back in the same cylinder.
     
  6. fortcollinsram

    fortcollinsram 1/2 ton status

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    My guess is that the ring gaps are hitting ZERO (VERY BAD) and exerting force on the cylinder wall...CHECK THE RING GAPS (insert ring in cylinder squarely and check gap...If the gap is to tight, the rings will expand and the end gaps will butt during operation and you will be screwed...
     
  7. SUBFAN

    SUBFAN 1/2 ton status

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    The next time you need to tap the rod-piston combo back out, get a block of wood, like a 1x2 or something. With new bearings, remove the bearing and put the piece of wood where the bearing was. Now use your hammer to 'tap' the combo out, and be prepared to catch it. A short length of rubber hose put on the rod bolts will help to protect that crank from nicks too.

    If you find anything going together with more than a little effort, then back off, and check it out. Assembling your own motor takes more time than you would think.

    Put each ring into it's respective bore, square it up, and use a feeler gauge to check the end gap. with only a hone, each might need to be filed a bit. To file the rings, use a fine toothed file, and knock a little material off, deburr it, and recheck. Take your time as removing to much will mean getting a new ring. (I know you won't use it anyway, right? /forums/images/graemlins/thumb.gif)
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    Put each ring into it's respective bore, square it up, and use a feeler gauge to check the end gap.

    [/ QUOTE ]

    No doubt. Take every bit of engine building advice you can get, and then take no shortcuts.

    If I had known NOTHING about rebuilding engines, when my block came back from the machine shop, I might have installed my .030 over pistons and rings into the .060 over bore the machine shop screwed up, and buttoned it up, just waiting to come apart when I finally got it running.

    I'm glad I've taken as much time on my motor as I have, (although 3 years is excessive lol) and not rushed it. Triple checked everything. Hopefully I missed nothing. (because I sure found lots of little quirks and problems)

    I've got too much money invested in this thing, and besides, I don't want to be pulling it back out! I'm sure most feel the same way.
     
  9. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    Just finished talking to the guy at the machine shop today and just when I thought things couldn't get any worse, they do. Turns out I have a cracked block (in the oil galley right where the wall separates it from the coolant passage. He said he would look around for some rebuildable 1-peice rear main seal blocks, but there aren't any garauntees. I've heard of people patching cracked blocks with JB Weld. Has anyone tried doing this or know someone who has? Does it work well?
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Did you have the block fluxed??

    JB weld won't hold up in anything that flexes. (don't care what some people might claim, been tried on aluminum t-case output shaft housings, and it failed) If it *doesn't* need to flex JB Weld might work, (such as plugging up a hole that doesn't see much pressure) but engines vibrate AND flex, plus they are expensive to replace, so I'd not even try it. That'd be throwing good parts to waste.
     
  11. Hardcore

    Hardcore 1/2 ton status

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    You'll need to put the rings in the cylinders and check the gap and grind them to spec. If you need some help (once you find another block /forums/images/graemlins/rolleyes.gif) let me know!

    Corey /forums/images/graemlins/thumb.gif
     
  12. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    What does having the block fluxed mean?
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Magnafluxed. Basically its a test for cracks in the blocks, even ones that you may not see with the naked eye.

    Then when you find out your block is cracked, after you spend all the money on it, you can "negotiate" with them. /forums/images/graemlins/smile.gif
     
  14. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Speed-Pro's rings for pistons with a 5/16" ring grove and a 4 inch bore should be E-251X for cast rings, and E-251K for moly rings. Just after that number on the box there maybe a small set of numbers such as 030 or 040, thats the oversize, if any. I usually drop just the top ring in and look for a gap of around .016-.018 before assembly.
     
  15. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    He said he would look around for some rebuildable 1-peice rear main seal blocks, but there aren't any garauntees.

    [/ QUOTE ]

    Is there a reason you need a 1 piece rear main seal block? The two piece ones are a dime a dozen.
     
  16. MOABDADC22

    MOABDADC22 1/2 ton status

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    Just a thought.......Check the casting # on the block (Stamped on the block above the timing cover). Alot of machine shops will have a bunch of SBC's around the shop and just use one of those engines for your rebuild (Usually an acceptable practice, unless you have a #'s matching high $$ car). Check and see if the last 4 digits of the VIN are stamped on your "cracked" block.

    If they are not. I would question the machinist as to whether or not your original block was cracked or not. If you can prove that the damaged block was not the block you dropped off........ /forums/images/graemlins/thinking.gif /forums/images/graemlins/thinking.gif The machine shop should make it right with you. /forums/images/graemlins/thumb.gif
     
  17. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    I bought the new block from a different machine shop than the one that was going to machine the old block. So why would they lie about the block being cracked when they only get $50 for a magnaflux rather than $400 for a complete machining. And I saw the crack and it was the same block that I dropped off. Thanks anyway.
     
  18. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    Is there a reason you need a 1 piece rear main seal block?

    [/ QUOTE ]

    Crank, flywheel, chance to use stock roller cam, less leaks. /forums/images/graemlins/smile.gif

    Only reasons I can think of. You are right, two piece main blocks are a dime a dozen though.
     
  19. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Not every one piece motor has a roller cam. My truck has a 1 piece RMS motor in it with no roller cam. I suppose it'd be nice.

    I notice you said less leaks, not NO leaks. I'd rather have it leak more often where I can pull the pan and fix it though rather than seperate motor/tranny all the time.
     
  20. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    Not every one piece motor has a roller cam. My truck has a 1 piece RMS motor in it with no roller cam. I suppose it'd be nice.

    [/ QUOTE ]

    I didn't say it came with one, but that "chance to use stock roller cam". I know the trucks didn't go roller until later ('96) but the block castings were the same, and the spots to bolt in the lifter retainer are there.

    [ QUOTE ]
    I notice you said less leaks, not NO leaks. I'd rather have it leak more often where I can pull the pan and fix it though rather than seperate motor/tranny all the time.

    [/ QUOTE ]

    I'd rather have a motor that goes 100,000 miles that doesn't involve me worrying about leaks before then.
     

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