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Help, MAN coolant problem - R6-800

Discussion in 'Engines' started by orlewis3, May 13, 2012.

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  1. orlewis3, May 13, 2012
    #1
    orlewis3

    orlewis3 New Member

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    Shady Side, Md.
    I just purchased a Cabo Express that has R6-800 MANs with approx. 1150 hours on each engine. As we were cruising along the ICW in Georgia yesterday, the port engine displayed an alarm "Coolant Press. Exp. Tank PSI" was low at 2.1 . The starboard engine had a reading of 10. I throttled back and idled both engines for 15 minutes while I researched the problem in the manual. We had been running about 1925 RPM which was about 70% load. We had to slow down periodically to pass slower boats and for speed zones. Each time there was a faint smell of anti freeze in the exhaust. After idling for 15 minutes, the reading improved to 4, which was in the green zone, so we throttled back up to 1500 and continued to run until we reached Savannah. Am now stuck here on a Sunday trying to figure out next step before we proceed.

    Any insight would be much appreciated.
  2. MSviking, May 13, 2012
    #2
    MSviking

    MSviking New Member

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    I have a 54 Viking with the MAN 1550s, I got that warning a few times at around 650 hours. I had planned on doing the 1000 hr service before summer season so I had that work done and they took care of the problem in the service. If memory serves me there was a small leak in the heat exchanger tube assembly. They removed and welded the leak and "refitted" the sealing surfaces on the exchanger assembly. Cost was $2500 for the work on the heat exchanger. I am fairly certain that was the cause of my problem.

    Either way I would contact a reputable MAN mechanic in your area and run the situation by them for guidance

    Good luck
    Robert
  3. MSviking, May 13, 2012
    #3
    MSviking

    MSviking New Member

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    I did a little quick reading on Boatdiesel.com, lots of people with similar issues had sensor problems others indicated that topping off coolant solved the problem, I would certainly check the coolant level and add if needed.
  4. orlewis3, May 13, 2012
    #4
    orlewis3

    orlewis3 New Member

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    Thanks. Apparently when adding coolant, you have to bleed the system and then pump it up with a bicycle pumps to 10 PSI. Any idea how to do this? Hoping to get the boat operational to get us back to Md. where I can have a MAN repair tech look at it.
  5. discokachina, May 13, 2012
    #5
    discokachina

    discokachina Senior Member

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    If you are any where near Savannah give these Thunderbolt Marine guys a call.

    They are on the ICW just South of the Savannah River.
  6. MSviking, May 13, 2012
    #6
    MSviking

    MSviking New Member

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    You only have pressurize the system if you completely drain it, to top it off, just open the coolant cap (regular looking radiator cap) and if you can't touch the coolant with your fingers, top it off. That's all you have to do.

    Robert
  7. CaptPKilbride, May 13, 2012
    #7
    CaptPKilbride

    CaptPKilbride Senior Member

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    Pressurizing the system with a bicycle pump avoids nuisance alarms.
  8. missnmountains, May 14, 2012
    #8
    missnmountains

    missnmountains Member

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    We have the schrader valves on top of the coolers. I was told the same thing on our 900's. If you add any fluid, you must pump it back up with a bicycle pump.

    Ken
  9. Capt J, May 14, 2012
    #9
    Capt J

    Capt J Senior Member

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    I manage a yacht with 1100 common rails, checked the coolant a few weeks ago before a trip and started the engines, the alarm went off with low coolant pressure on the port engine......shut the engine off, checked the sensor connection on the motor, started it, never saw the alarm again......I just checked the coolant again in both motors and pumped it up with a bicycle pump, so shall see.
  10. crackerD, May 14, 2012
    #10
    crackerD

    crackerD Member

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    How many hours on the engines? I have the same engines- switching out the expansion tank caps solved the problem.

    Either way, I wouldn't be too concerned. The engines will "self protect" so run 'em hard and if there is a problem you'll be fine.
  11. orlewis3, May 16, 2012
    #11
    orlewis3

    orlewis3 New Member

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    Many thanks to all that replied. Problem ended up being bad turbo housing. I was able to continue running to Wilmington NC by adding water every time pressure went down to 0 in expansion tank without using bicycle pump. Slowed engine down to idle, filled up expansion tank, cranked back up to 1800 RPM, pressure built back up to 3 or 4 PSI which slowly went back down when engines were throttled back (Decided to run in ICW as a precaution). Had I been able to stay at 1800 RPM, there wouldn't have been any loss of pressure. Made it safely to Wilmington with your assistance. Thanks again for all the help and advice.
  12. orlewis3, May 16, 2012
    #12
    orlewis3

    orlewis3 New Member

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    BTW, the mechanic that is switching out the bad turbo said that the only time pumping the system is required is when completely draining coolant and reinstalling. Pumping is needed to properly bleed system of air. Once that has been done, pumping no longer needed when just topping off system. Open radiator cap, top off system, run engines at 1,000 RPM for 5 minutes, open radiator while engines at 1,000, top off again and re secure cap. His opinion, for what it's worth.