Help With Cat 3406B Issues

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by OldRed98, Dec 26, 2020.

  1. OldRed98

    OldRed98 Light Load Member

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    I just bought an old Dump Truck from the equipment auction. I got a good deal but unfortunately I don't know any of the trucks history.

    Its got a Cat 3406B. The first day I started it up, It smoked a lot of white smoke on cold start but the engine seems to idle smooth. I put some Amsoil Cetane /Diesel clean in the tank and dumped out the water fuel seperator. After idleing for an hour it really cleared up. But as it warmed up I got more smoke coming from the blow by tube. I started the truck again today and the smoke issue is still there but its much better. After idling for an hour, the smoke was almost gone (except for blow by smoke)

    Issue #1: After bringing truck to full operating temp. my oil pressure seems low. about 15-18PSI @ 600RPM and 40PSI at 1000 RPM. I've seen the bottom of spec range is 15PSI. Should I worry about this before driving the truck anywhere? Maybe an oil pickup issue or pump.

    Issue #2: I have some side to side play in the turbo shaft. It looks like the turbo has lightly scraped the side before. Could a bad turbo also be causing my smoke and blow by? Should I be ordering a new turbo ASAP? I don't want to break a blade off. If so, what Turbo would you recommend for replacement?

    I appreciate any advice. Its my first CAT motor and I'm trying to think through repairs on this truck. I got it cheap enough that I can afford to do some repairs and upgrades.

    Thank you
     
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  3. OldRed98

    OldRed98 Light Load Member

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    11B727F1-1E30-4729-A6C8-1DCED05DAF35.jpeg Here’s a pic of the turbo inlet.
     
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  4. PSM379

    PSM379 Light Load Member

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    I’m not a professional, the smoke wouldn’t be caused by the turbo as far as I know though. The smoke could be caused by bad timing advance, and the low oil pressure could be a few things, start with gauge that’s the cheapest, is there fuel in the oil, oil pump etc.
     
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  5. OldRed98

    OldRed98 Light Load Member

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    I forgot to mention, I'm sending an oil sample off to Blackstone for an analysis. That would hopefully tell me if theres fuel or coolant in the oil. Oil looks and smells clean though. Clean looking oil can also be because theres a bunch of fuel in there. Its almost too clean looking for an old 3406B. Deluted oil could cause low oil pressure. Hmmmm.
     
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  6. baha

    baha Road Train Member

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    Next time you get eng. warm drain the oil, and change the filter, when the sample comes back it may tell a lot, the truck was idle a lot while at sale lot, fresh oil should bring oil press. up? You may get a table spoon full of the old oil and hold a torch under it to see if it crackles when it burns that can tell if fuel is in oil the old way?
     
    Last edited: Dec 26, 2020
  7. OldRed98

    OldRed98 Light Load Member

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    Thats a good Point. I have no idea the last time this oil was changed. I'm hoping to avoid pulling the oil pan and checking the pump. I had a leaking oil pickup tube on my N14 cummins and it caused low oil pressure.

    I just hope I can get away not doing an inframe on the CAT 3406B yet.
     
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  8. AModelCat

    AModelCat Road Train Member

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    I wouldn't throw an oil pump at it for the sake of trying to cure an oil pressure issue. Worn out bearings on the crank and cam are going to give low oil pressure too. As will diluted oil. Cheapest thing first would be to send an oil sample off and see if its dilluted.
     
  9. Brettj3876

    Brettj3876 Road Train Member

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    Turbo's on its way out. Shouldn't be scraping the side like that
     
  10. AModelCat

    AModelCat Road Train Member

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    Caterpillar reuse and salvage guidelines indicate any contact between turbine/compressor wheels and housing is grounds for replacement.
     
  11. OldRed98

    OldRed98 Light Load Member

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    Thank you!!! I figured that might have been the case on the turbo. I will start looking for a new turbo and work on getting my oil sample done.

    Someone has done some work on this truck before. several hoses and coolant lines are new. And it has almost no oil leaks. Wish I knew the history.
     
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