So my MBN blew a head gasket.....

Discussion in 'Trucks [ Eighteen Wheelers ]' started by Freightlinerbob, Jan 17, 2016.

  1. Freightlinerbob

    Freightlinerbob Road Train Member

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    03' MBN that thinks its a 6NZ, if you get my drift.. speaking in code, bla bla bla. Engine has approximately 800,000 on an inframe. impossible to tell accurately because Western Star did not equip their trucks with odometers in 2003, relying on the dashboard computer to count mileage. Since the ECM was re flashed, it started at zero again. It has about 300,000 on a bearing roll in. Aftermarket manifold and turbo. Generaly, I've been happy with the performance and MPG. I'll know by Monday afternoon how far I need to go to fix it, but in the mean time I'd appreciate your thoughts on the following:

    Is it reasonable to just replace the H/G and carry on? I understand there may be a few liners that will be below spec on deck height, so should I ask for all liners to be pulled and deck height reset to something higher than stock?

    If I decide on a Cat warranty type inframe, I'll have to set it back to an MBN. This doesn't appeal to me at all, so would it be smart/OK to get a genuine rebuild without a warranty? ( a CAT certified tech will be doing the work and is highly regarded in my area).

    I've read about MBN deck height being too low and that combined with 31PSI boost this motor is now capable of, causing the problem I'm having now. Is this accurate information? What can I have done to fix this?
     
    Last edited: Jan 17, 2016
    Reason for edit: Content
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  3. Cat sdp

    Cat sdp . .

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    You have to measure everything up and see how it looks.....if the heights are all ok (which they won't be) you could just do the gasket . If the heights are good .

    With 800k on rebuild if your going to keep it I'd probably do everything . Your warranty issue is a tough one. Some will over look it most won't.
     
    Last edited: Jan 17, 2016
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  4. Superhauler

    Superhauler TEACHER OF MEN

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    Don't just replace h/g. Liner protrution if the reason it went. Insist on .004 to.006 on protrution. Anything lower with HP won't last. I'm in the middle of an out of frame on mine putting my head on tomorrow. I post pic's of what I did to my ne we head that I hope will solve h/g issues. If you can find a head that does not have relief cuts in it that will help alot.
     
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  5. rollin coal

    rollin coal Road Train Member

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    Mine thought it was a 6NZ and the CAT house that did the inframe left that part alone. I told them up front not to change any of that and they were OK with it. I told them I didn't have issues or problems with the "stock" program and really did not want to have to put a waste gated turbo back on it as the one I had on it was just fine. I guess every CAT house is different. I agree with these guys check and make sure liner height is on cause you sure don't want to go through this again.
     
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  6. Freightlinerbob

    Freightlinerbob Road Train Member

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    well, a cracked head and three cracked pistons kinda made up my mind about how much to fix. Platinum here I come. Doing the radiator and oil cooler as well.
     
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  7. kranky1

    kranky1 Road Train Member

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    Deck Height is beyond critical. Your engine i would be tempted to put cylinder packs in and button it up. No point in touching a C15 bottom end at 800k kms. Be an idea to find out if a liner or liners dropped from erosion of the block or if they were just installed at "whatever" height to begin with. I have a BXS that runs 72psi+ of manifold pressure with no gasket issues. Those liners were set at exactly .007. That engine has 1.6m kms on it and the bottom hasn't been apart yet. Runs 57psi oil pressure at 180deg oil temp and still hits 70psi on a cold start. Rotella Rules. =) Hope you get on the go without too much dough.
     
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  8. little cat 500

    little cat 500 Road Train Member

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    any body ever have the spacer plate milled to get liners in spec i know theres a thin an stock plate its been done just asking if any eles tryed it
     
  9. Superhauler

    Superhauler TEACHER OF MEN

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    Yes make sure they have a good magnetic table to do it on. And mic it after to check.
     
  10. Superhauler

    Superhauler TEACHER OF MEN

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    One thing I learned is cat has what they call classic parts and standard parts. Classic parts are cheaper but not as good of quality as standard parts. Stick with the standard parts.
     
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  11. Oxbow

    Oxbow Road Train Member

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    Thanks Superhauler, I wasn't aware that engine internals were even available through the Classic system.
     
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