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Exaust manifolds cracked. Oxy/acet melt fix?

Discussion in 'Truck & Equipment Repair' started by terrapro, Sep 19, 2012.

  1. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    I have a set of heads in the machine shop being rebuilt. While I have them off I have a crack in my drivers side exaust manifold, can I melt the crack back together with my oxy/acet torch with success or should I just replace it?
     
  2. Morrissey snow removal

    Morrissey snow removal PlowSite.com Addict
    Messages: 1,799

    are they cast or steel i would weld them up unless they are totally rotted
     
  3. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    No they are solid, just typical crack chevys get. They are stock cast not steel tubing.
     
  4. TJS

    TJS PlowSite.com Addict
    Messages: 1,342

    Nope. Cast iron. Forget it. They are cheap on ebay.
     
  5. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    Forget welding them manifolds don't weld worth crap not even 99.99 nickel will bond them. The expansion and contraction will cause even brazing to crack.
     
  6. Morrissey snow removal

    Morrissey snow removal PlowSite.com Addict
    Messages: 1,799

    never realy thought of that good point
     
  7. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    Well I broke off a stud on the exit side so I had to blow it out with the torch and I keep breaking and dulling drill bits trying to drill a good hole so I might as well buy new I guess.
     
  8. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    Can these be replaced with a set of flowtech headers?
     
  9. Holland

    Holland Senior Member
    Messages: 605

    Help to know what truck you're talking about
     
  10. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Look on the Internet for them. I picked up a pair for my Ford 5.8 for $105 dollars. With free shipping! A bolt - stud kit from NAPA was $20. The cheapest manifolds I found around here were $180 a pair.
     
  11. Builder630

    Builder630 Member
    Messages: 64

    I replaced the passenger side exhaust on my 89 gmc3500 5.7. I had like 3 snapped studs... I welded a nut onto the stud with an arc welder( my MIG wasn't working). After a little lube I backed out the studs with the welded on nuts with no problem.
     
  12. Builder630

    Builder630 Member
    Messages: 64

    Btw I did try welding a crack on the cracked manifold I was removing, and there was way too much distortion. The bolt holes wouldn't line up around the welding.
     
  13. DIRISHMAN

    DIRISHMAN PlowSite Veteran
    Messages: 4,256

    Hey Mick are you say you got Headers or manifolds?/ I have the same motor in my 96 250hd 5.8 .Didnt think the 5.8 had this issue liker the 5.4
     
  14. SnowPro93

    SnowPro93 Senior Member
    Messages: 375

    i just put manifolds on my 02 2500hd. I had an exhaust leak from snapped studs but while there out you might as well replace them. I think mine were about $175/pair for stock replacement with upgraded gaskets and the bolt kit. Headers I believe should bolt in place of stock and most of the time are cheaper just make sure you use a good gasket and not the garbage composite ones or you'll have problems.
     
  15. DIRISHMAN

    DIRISHMAN PlowSite Veteran
    Messages: 4,256

    Yah lookin at headers and will use the best I can find lookin at a set of kOOks
     
  16. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    My Manifolds on the 5.8 for the most part just rusted out. They got cracks when the casting got too thin. I replaced them with OEM style manifolds. The bolts and stud replacement is just the way I do things. I had to drive a 12mm impact socket onto the rusted globs of nuts& bolts.. I got everyone out with a little flame wrench persuasion.
    The truck has been a plow truck it's whole life. This was at least the 3rd set of manifolds. The last bolt I took off had a lug nut for a spacer.
     
  17. DIRISHMAN

    DIRISHMAN PlowSite Veteran
    Messages: 4,256

    Geeze a lug nut what no washers
     
  18. DIRISHMAN

    DIRISHMAN PlowSite Veteran
    Messages: 4,256

    What ya think about headers
     
  19. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    They must of put the wrong lenght bolt in the last bolt hole.
     
  20. DIRISHMAN

    DIRISHMAN PlowSite Veteran
    Messages: 4,256

    Nice one good thing they didn't build them for a living