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Time for a rebuild.Im at a cross road. need advice

Discussion in 'GM 6.5 Diesel Engines' started by My6.5, May 12, 2018.

  1. My6.5

    My6.5 New Member

    May 11, 2018
    Been a long time researcher but this is my first time posting here.

    It looks like I'm going to need a rebuild. Not sure what is wrong but I'm thinking crankshaft.

    I'm at a crossroads though. I can pay my guy around $3000 for a rebuild give or take. Or I was thinking I could get a donor truck (1997 gmc) with 95000 miles on it for $1500. The plus with the donor truck is it has new wheels and tires. Suspension parts I can use and also the newer double thermostat set up.

    I just installed a new injector pump 3 months ago on mine before engine went out last week so I'm good there. I figure I get the donor truck put new injectors and glow plugs.

    on one hand with the rebuild I know what I got.= peace of mind.
    on the other hand I get an engine with pretty much low miles in diesel years , plus some bonus parts.= crapshoot on not having clear history of engine but lots of bonus parts.

    What do you guys think?

    fyi I have a 1996 z71 6.5 "s" code
    MrMarty51 likes this.
  2. ak diesel driver

    ak diesel driver 6.5 driver

    Feb 7, 2009
    Either option is kinda a crap shoot. I'd pull the pan on yours and see if the block is cracked before paying someone to discover that for you.
    I'm usually in favor of fixing what you have vs buying unknown problems.
    WarWagon, MrMarty51 and Jaryd like this.
  3. MrMarty51

    MrMarty51 Well-Known Member

    Aug 1, 2017
    Miles City, Montana
    Teds Trucks has some mighty fine options too.
    You can find him on ebay and also on the banner add when it spins around to his name.
    Welcome My6.5.
    WarWagon likes this.
  4. WarWagon

    WarWagon Well it hits on 7 of 8...

    Nov 15, 2009
    Doesn't hurt to post up symptoms before assuming the worst. Broken flexplates or failed harmonic dampers make a lot of noise...

    These engines are throwaway engines and consitered scrap in the engine rebuilder world. Mainly due to main web cracks. A used Optimizer is worth a rebuild because the blocks are better.

    Doing it yourself anything goes. Some of us like to see how far they can go frugaly.
    MrMarty51 and Jaryd like this.
  5. My6.5

    My6.5 New Member

    May 11, 2018

    Well truck ran fine no issues then at a stop light it got super loud. Step on the accelerator and super super loud. Like I threw a rod. It was so loud I decided on not limping it the rest of the way home. I noticed the oil pressure dropped some as well. I did notice a slight knocking sound the past few months but it would come and go. I thought about it being possibly harmonic balancer.

    Fortunately the mechanic I deal with loves these 6.5 diesels. He hasn't seen it yet but we talked about options a few days ago. I wish I could wrench on it myself but I don't have the space or the time to rebuild it myself.

    Thanks for the advice on the flexplate or harmonic balancer. I thought when balancer went out it automatically meant failed crank on these engines. I will look into that and keep my fingers crossed.

    The donor truck is actually a truck that still gets used on occasion. I think the owner has one too many trucks and doesn't want it anymore. I could buy his truck and call it a day if I wanted. I just like my truck better.
    Last edited: May 13, 2018
    Will L., btfarm and MrMarty51 like this.
  6. btfarm

    btfarm 330,000 Worth and counting Staff Member Moderator

    May 12, 2008
    Sandwich, Illinois
    Welcome To the Truck Stop. There's enough 6.5 expertise here to either walk you through a rebuild it yourself scenario or if not they DEFINITELY will keep your mechanic honest. So be sure to keep us involved.
    Husker6.5, n8in8or, WarWagon and 3 others like this.
  7. Will L.

    Will L. Well-Known Member

    Jan 25, 2013
    Boulder City Nv
    Well tell him too sign up here and say hi too. This is a good home for 6.5 fans. Always nice to meet more people with the same addiction- haha.

    I would say have him drop the pan and flywheel cover to see what’s going on, and make a decision from there.

    As for the 97 for 1500- Thats a smokin deal if it runs good and is a half decent rig imo. Guessing from Cal it isn’t a rust bucket, most aren’t. Around here if it is a 2wd that would fetch $3k, another grand for 4wd- provided it looks ok and a/c works.

    I would be tempted to buy it before the deal gets away, and if needed then use the engine. If yours turns out ok for simple fix then sell the other for a profit and pay for the repair of yours.

    If you do rebuild yours or use the take out, I suggest pop in new bearings and gapless rings while it’s out. Depending on cash availability, there are other things to think about inside the engine - but it all hinges on cash being available.
  8. Rodd

    Rodd Recruit

    May 5, 2008
    Antelope, CA
    Welcome! What part of Cali are you in? There are guy's up north and south here. Mine made a loud noise too but it ended up being the harmonic balancer. It did sound like a rod and vibrated like heck. It sheered off the key and tore up the keyway but with a little Jb weld to hold the new key in and red locktite on the bolt it's been going for about 20k miles now. It's an easy diagnosis. Turn on the truck and look at the HB. If it is the culprit it you will see it.
    Will L. likes this.
  9. My6.5

    My6.5 New Member

    May 11, 2018
    what am I looking for in terms of the behavior of the harmonic balancer when I turn it on. Will it be wobbling or something?
  10. Jaryd

    Jaryd Oh the sound a 6.5 makes

    Nov 27, 2016
    Hodges, SC
    Yes it will be wobbling.

    Before you try to crank it I would climb under the truck and try and move it by hand. Give it some good jerks and if it moves ANY then I would replace it.

    Welcome to the forum. Good folks around here.
    n8in8or, WarWagon and Will L. like this.
  11. NVW

    NVW Well-Known Member

    May 5, 2008
    Castor, AB.
    Welcome to TTS, all good advise given.
  12. My6.5

    My6.5 New Member

    May 11, 2018
    I didn't have time to do it today because of mothers day but Im going to check it out tomorrow. If it is in fact the harmonic balancer do you think there is a good chance that's the only repair? Or wishful thinking.
    Good deal thanks
  13. NVW

    NVW Well-Known Member

    May 5, 2008
    Castor, AB.
    Without dropping the pan you won't know if the crank is the problem. Six bolts on the bell housing lower inspection cover and one or two on the brace rod will let you inspect the flexplate or flywheel, depending on auto or standard trans.
  14. deejaaa

    deejaaa Diesel Beginner

    Sep 19, 2008
    removing the belt will make it easier to move by hand.

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