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New bad noises from the 3406B!

Discussion in 'Trucks' started by skyking1, Jun 7, 2022.

  1. skyking1

    skyking1 Senior Member

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    When I started home something happened and she started hammering under load. I also noted more of a blowby smell, but that could be me.
    I pulled over and listened, looked around, and it just does not sound bad at idle. It does not sound bad standing next to it and free revving it at the pump either. It only sounds like this when it is making power. It sounds to me like a gasser with a cracked manifold.
    Pressures and temps were normal, oil looks OK. Tomorrow I will give the coolant another look too.
    Here is a video for the sound. i was in stop and go, and it only chugs when making torque.
    I tried embedding it but not go. Click the link and tell me what you think it might be?
    https://youtube.com/shorts/f8LZUTyNjIQ?feature=share
     
  2. 398370

    398370 Active Member

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    Pop the valve covers look real hard at valve train. Missing button on rocker ??
     
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  3. Coaldust

    Coaldust Senior Member

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    It’s half crankshaft speed, so suspect valve train issue. Pop the covers off. Broken valve spring.
     
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  4. JPV

    JPV Senior Member

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    You might crack injector lines first to see if you can isolate the cylinder then look at the valve train. If it looks fine I would cut the filter too see what you see. If that looks good and there are no exhaust leaks (that's kinda what it sounds like to me in the video) I am not sure what it could be.
     
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  5. Coaldust

    Coaldust Senior Member

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    It does sorta have an exhaust leak sound to it. Good thinking.
     
  6. skyking1

    skyking1 Senior Member

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    thanks guys.
    broken valve spring and I might have some contact, or just an ugly leak at that valve?
     
  7. skyking1

    skyking1 Senior Member

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    It is at the truck shop now. We shall see what comes back and I will report.
     
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  8. Coaldust

    Coaldust Senior Member

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    3406B down! If those wheels ain’t turning’ you ain’t earning. Put me on the job. I can fix her up.
     
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  9. skyking1

    skyking1 Senior Member

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    Reporting back with a six broken exhaust studs. Once one goes apparently the other ones are right along the way! Parts are on order.
     
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  10. Coaldust

    Coaldust Senior Member

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    Thanks for the update.
     
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  11. terex herder

    terex herder Senior Member

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    Those cat exhaust studs are the worst I have ever tried to remove. Normally, I will weld a handle on the stud and can back it out with a pair of vise grips. Every filler rod I tried, the weld would break off the stud and the end of the stud was glass hard. I then had to grind out the hard spot before I could drill the stud. I ended up making a drilling plate that would locate on non-broken studs and hold the drill bit on location to drill a pilot hole in the stud. I was then able to remove the broken stud with shop made un-easy outs.
     
  12. Jonas302

    Jonas302 Senior Member

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    Finally someone else that wont use the word easyout lol

    I can't remember the 3406b truck I did being to bad but I will never forget doing a cat loader last summer out in the mosquito filled gravel pit it had those glass hard studs in it 3 days drilling the only thing that would even come close to cutting was carbide bits they would last for half a stud or so

    Did a Mack last week and they all welded and unscrewed on the first try even though the break was recessed in the head quite a ways I was a happy camper!
     
  13. Truck Shop

    Truck Shop Senior Member

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    Cat makes and or sold a drilling template for the 3406.
     
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  14. DB2

    DB2 Senior Member

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    And special Artu drill bits
     
  15. kshansen

    kshansen Senior Member

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    This is what is shown in "Dealer Service Tool Catalogue":
    stud tools.png

    However this does not seem to show the template that I recall the dealer using when we had some broken studs on a 3408. I had managed to remove all but a couple by welding nuts to the broken parts and removing them. Dealer guy also tried that with no luck. He then had a plate/template that bolted to the head and accepted bushings to guide the special drill bits to drill out the broken studs.

    I had a little better luck doing a 3306. Some studs took a few tries to weld on the nut to remove the studs but managed to get them all out.

    One trick that helped on some was to place a 3/8 inch flat washer around the broken stud and weld that to the broken bit and then place a 1/2 inch nut on top of it to weld to it. I think that gave you the ability to get better penetration into the stud and also put more heat into the broken stud so when it cooled a little it would shrink a bit.
     
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  16. skyking1

    skyking1 Senior Member

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    I don't feel bad at all about letting somebody else do this job :)
     
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  17. skyking1

    skyking1 Senior Member

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    It's one of those parts that are more about time and less about miles/hours. On the plane they would rust away. This engine only has 210,000 miles but it's 30 years old.
     
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  18. Coaldust

    Coaldust Senior Member

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    Broken Caterpillar exhaust manifold studs put bread on my table for many years.
     
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  19. heymccall

    heymccall Senior Member

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    ESAB All State Stud Plus welding rods.
    You'll never take below flush broken studs out another way.
     
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  20. Bluox

    Bluox Senior Member

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    Number 4 is the drill guide.
    Bob
     
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