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Caterpillar C18 Engine Problem

Discussion in 'Technical Discussion' started by T.K., Oct 18, 2019.

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  1. T.K.

    T.K. Senior Member

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    The yacht is fitted with two Caterpillar C18 engines. The starboard engine will not achieve an engine speed above 1200 rpm. The local Caterpillar dealer has been struggling with the engine for months with no success and finally the engineer removed a blind plug from the turbo charger and fitted a ball valve in it's place which he left slightly open as seen in the image below. With this solution, the engine now achieves an rpm of 2300. However, I am not convinced this solution of fitting a relief valve to the turbo charger makes sense and cannot be a final repair to the problem. Something must be causing the problem and lack of performance. Any idea what the problem could be and why is the engine now performing as it should with the ball valve fitted to the turbo charger and left slightly open? Thank you.

    IMG-20191018-WA0017.jpg
    Last edited: Oct 18, 2019
  2. Capt Ralph

    Capt Ralph Senior Member

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    Your waste gates are not working causing a bit to much air.
    Or the pressure sensor is messed up.

    If your tech has the proper computer setup, he should of seen the data on his laptop.
  3. T.K.

    T.K. Senior Member

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    Thank you Captain Ralph. They do have the proper diagnostic tools but I doubt they have the ability to use it. We replaced the pressure sensors but the waste gate was not checked.
  4. Capt Ralph

    Capt Ralph Senior Member

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    Your beast have two turbos, in the back and on the side. I think each has a waist gate.
    Good luck.

    BTW
    Dockmaster is currently re-powering with C18s.
  5. T.K.

    T.K. Senior Member

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    Correct, the engine is fitted with two turbo chargers. I will check both waste gates. Should be a simple fix. Thank you Captain Ralph for the suggestions.
  6. T.K.

    T.K. Senior Member

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    I was told that waste gates on Caterpillar engines cannot be replaced and the complete turbo charger will need replacing if a waste gate has failed. Is this correct?
  7. Capt Ralph

    Capt Ralph Senior Member

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    Depends on the failure;
    It could just be stuck. Lil penetrate oil and patience may help.
    The pressure diaphragm should be serviceable.
    The shaft and internal damper would require a new turbo chunk.

    You should be able to move the external lever by hand.

    Has anybody recorded an actual boost pressure yet?
    Would you have any EGT or back pressure readings also?
  8. rtrafford

    rtrafford Member

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    Yes. And if the gates are free, you might have bad sensors even if they aren't throwing a code. I've been down this same rabbit hole.
  9. T.K.

    T.K. Senior Member

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    Thank you Gentlemen for the sound advice. I will have the waste gates thoroughly checked. I am very surprised the local Caterpillar technicians were not able to identify the problem.
  10. DOCKMASTER

    DOCKMASTER Member

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    Please update as you continue to work this issue. What year and hp are the C-18s?

    Also, for what its worth, on some commercial ships that we have installed larger CAT engines and gens on we have had trouble getting local international CAT dealers to diagnose and correct issues. We often have to fly technicians form US to deal with the problem. We haven't dealt with this in your area that I'm aware but it is a regular issue in Far East.
  11. T.K.

    T.K. Senior Member

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    Thank you Dockmaster for your message. The C18 engines are a 2013 model year and are C18 1150. The engine power is 1136.
  12. DOCKMASTER

    DOCKMASTER Member

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    I’m putting same engines in my 54’ Donzi currently. You don’t hear about too many issues with these engines. Hope you find the problem soon.
  13. Capt J

    Capt J Senior Member

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    Also what is load at 1200 RPM's? I once ran a new boat where they put the wrong props on it and the Cat C18's wouldn't let it go over 1200 rpms because they saw too high a load factor and put it in safe mode.
  14. T.K.

    T.K. Senior Member

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    Thank you Captain J. It won't be a propeller problem. She's been running well for the last 5 to 6 years. The deterioration only started in the last few months.
  15. T.K.

    T.K. Senior Member

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    Thank you Dockmaster. I am having the waste gates checked and will revert.

    Good luck with your installation.
  16. T.K.

    T.K. Senior Member

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    Are you familiar with how the waste gate on the C18 Engine is adjusted and at which pressure does it need to start opening?
  17. DOCKMASTER

    DOCKMASTER Member

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    I do not have this info. I would think any authorized CAT Tech would have it though.
  18. Capt Ralph

    Capt Ralph Senior Member

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    Fixed yet?
  19. T.K.

    T.K. Senior Member

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    Still in process. The local CAT dealer is impossible to deal with. We removed the intercoolers and found the seals had failed and the intercooler cores were blocked with salt deposits. We cleaned them. The engine performance has improved and WOT rpm is now over 2250. The engine acceleration to 2250 rpm is normal until the coolant temperature reaches 70degc. As soon as the coolant temperature increases above 70degc, the engines start struggling going above 1200rpm.
  20. Capt J

    Capt J Senior Member

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    Where is the salt that is getting into the intercoolers coming from? That is what you really need to figure out. How old are your aftercoolers?

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