Repairing cracked T4 heat exchanger

Discussion in 'Mech Tech' started by orwell84, Nov 20, 2020.

  1. 9CA50E03-EA34-41C9-9ACE-7873A7595A60.jpeg B5AA9BCF-0815-49D1-96C5-A9C43A6B4FFB.jpeg Hello,

    I am repairing a set of Type 4 heat exchangers. I have all the tins welded up but after blasting the headers found a crack.

    I think they are cast iron but I’m not sure what type. I was considering brazing or MiG welding them. The pipes are still quite solid so I am basically plugging the hole. I think at one time they may have been run without the rear support mounts installed which might explain the crack.

    Any thoughts?

    Thank you
     
  2. Brazing might be best if you've got the gear.
     
  3. Faust

    Faust Supporter

    I would weld a band all the way round it as it looks thin all over ...either that or get some decent second hand ones .
    I can see why you wish to repair as they are original, judging from the sharper longer fins .
     
  4. Any idea what they are made of? Cast iron or cast steel?
     
  5. davidoft

    davidoft Sponsor

    the pipes just steel tube, the ends seem to be cast , you can weld that bit, I would plug a plate around the whole thing
     
  6. Just be careful , if they have corroded through where you can’t patch them you will get fumes blown on to van if you use heating
     
  7. Ok, that makes sense. If they are just steel, they should be easy enough to MIG weld up.

    I will test them for internal leaks by plugging the ends and blowing through them or using compressed air.
     
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  8. mikedjames

    mikedjames Supporter

    Once a welder goes near that you may find more of the tube needs patching, as there are some other places along that tubing that look thin. A simple way to find out is to tap it firmly with a ball pein hammer. If the surface gives way, it was pretty thin and needs patching.. In the end you may find it easier to fabricate new tubes and weld those in instead.
     
  9. I am also going to make sure the sealing surfaces to the heads are flat with a machinist straight edge or a surface plate as well as torquing them to the heads in the bench and test them for leaks. I always forget to retorque them again after driving for awhile. Usually I end up doing it after I get a leak and end up squashing the copper sealing ring after it has shifted.
     
  10. Yeah, I know what you mean...metal vanishing as soon as the wire hits it. That’s how it usually goes. Since it’s steel, I will cut it back to good metal and weld in a patch. I have a spare somewhere I will also have a look at.

    Worst case scenario, I have to scare up another used one. It’s usually the tins that are in bad shape, the inside is usually ok. Since I’ve already got good tins...

    I got all winter and plenty of other things to do.

    Thanks again.
     
  11. I Mig them, but that looks pretty well shot.
     
  12. Yeah, that one’s shot. It also leaks where the pipe meets the flange to the the head. Not to mention it’s really pitted in many places. But the pipes seem to be steel and weld as such.
     
    Last edited: Nov 21, 2020
  13. Zed

    Zed Gradually getting grumpier

    That part of mine was ok but an inch of the other end and the plates needed replacing.
    P1010111_zpsfzwnmkqa.jpg
     
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  14. davidoft

    davidoft Sponsor

    that’s barely a scratch
     
    Zed likes this.
  15. davidoft

    davidoft Sponsor

    that’s not bad at all almost couldn’t be better , can weld that easy peasy
     
  16. Yeah, I know you Redcoats don’t run away from rust. The other problem with this one is that it leaks where the pipe meets the header flange. I don’t know how the factory sealed these up. F4BFE3DD-0B8E-431D-9191-3600B393F606.jpeg
    I have another one with good pipes to the heads but the silencer end is shot. I cut some flanges and pipe sections from an old EMPI collector.

    39B5BCF9-ED24-4EB4-AFF7-2923CCE2017F.jpeg
    And my ex wife called me a hoarder. That’s some fine Chinesium steel right there boss. I will need a tetanus shot before the Covid vaccine.

    I don’t really need the heat that badly as I have a BN4 heater and some good j-pipes. I guess I am doing it for sport. That and my Herr Doktor Suess heating system that I just have to try.

    891A693F-D35A-40FC-A564-A454BD3FFEB9.jpeg
    ...or giant steampunk crack pipe...a Beluga kazoo...The blower fan will draw air from the original heating vent behind the walk through. I have already pulled out the Y pipe and put it through the blast cabinet and hunted down or made various bits and pieces, so I am too far in to quit now.
     

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  17. Good news! A friend of mine received a pair if decent looking heat exchangers from a guy whose bus he was working on and offered them to me. Tins are rough but I’ve got good tins. Worst case I know I can weld up what I have. His friend with the bus was looking for a 009, which I offered him from my parts stash. Decent one from the mid 90’s barely used. :)
     
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