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  1. #1
    Join Date
    Nov 2005
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    Default Volvo Engine Cooling System

    Your thoughts please?

    After just having had my engine serviced (MD2040) last month, I have discovered a problem with the cooling system. All is fine when firing up the engine in the marina and we begin every trip OK. However, after sailing for a few hours (heeled over), upon starting the engine, no water is being pulled through the cooling system. The only way to rectify the problem is to “prime” the water filter with water (which is empty!) and fire up the engine again. At first, I presumed we had picked up a bag etc over the water intake on the sail drive and “bled the system”. However, the same problem happen the next day - left marina OK but no cooling water appearing after we started the engine to return into marina. The problem does not occur when we fire the engine in the marina, even after leaving it for a few days thus I assume no leak. Also, the bilges are dry which confirms this. I have checked impellor - new a month ago and all is OK. (System works fine other than after we have been out sailing). I can only guess that the water is being siphoned out as we are heeled over. I have spoken to the marine engineers who serviced the engine and they appear a little confused to say the least. Has anyone got any ideas?

    Your comments are much appreciated.

  2. #2
    PCUK is offline Registered User
    Location : Mid Devon
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    Default Re: Volvo Engine Cooling System

    If it was OK before the service then it is something done during the service. A small air leak would prevent the pump priming as the pump should be able to prime from dry regardless of boat's attitude.
    UKIP - For derogated red diesel!

  3. #3
    aztec's Avatar
    aztec is offline Registered User
    Location : Poole Dorset
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    Default Re: Volvo Engine Cooling System

    assuming the pick up isn't "out of the water"

    but as mentioned the pump should prime from dry.

    does it happen when heeled one side and not the other?

  4. #4
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    Nov 2005
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    Default Re: Volvo Engine Cooling System

    Thanks for the response, in answer to your question:

    Pick up is not out of water.

    Will not rum from dry - need to prime water filter to get it to start. This sometimes take a few goes as I expect it is needing to pull water through impellor and into heat exchanger.

    Don't know about which side causes problems as it was only noticed (presumed fixed) after a days sail.

  5. #5
    aluijten's Avatar
    aluijten is offline Registered User
    Location : Dordrecht, The Netherlands
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    Default Re: Volvo Engine Cooling System

    Do you have the correct size impeller mounted. If the width/height of the impeller is not sufficient, air can leak past the blades, beteen the impeller 'compartments', this could explain why it is not self-priming anymore.

    The impeller should have a pretty tight fit in the housing.

    Regards,

    Arno

  6. #6
    Join Date
    Nov 2001
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    Default Re: Volvo Engine Cooling System

    Double check that the pin in the hub of the impellor is actually glued to the outside. I've had experience where the pin spun round - but the impellor didn't.

    Worth a check - its not unknown

    Donald

  7. #7
    Join Date
    Oct 2005
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    Default Re: Volvo Engine Cooling System

    This used to happen on my old boat with a MD6B. After every hard sail I had to "burp" the air out of the system at the thermostat. The problem seemed to get better after replacing the anti-siphon valve, no idea why [img]/forums/images/graemlins/cool.gif[/img]

    Incidentally, the intake was about a foot down from the top of the keel.

  8. #8
    Join Date
    Mar 2003
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    Default Re: Volvo Engine Cooling System

    There is an air leak problem somewhere from the raw water pump itself to the seacock. Number of possible causes: the pump itself wears on the back and front faces so if a marginally smaller than normal impellor (say a pattern one) was fitted, or maybe a jubilee on the pipe to the seacock wasnt tightened properly, or maybe a pipe was bent and cracked.

    All you need to do it to start off at the seacock and carefully go through every inch of the system up to and including the pump itself. Replace the impellor if nothing else works.
    this post is a personal opinion, and you should not base your actions on it.

  9. #9
    nedmin is offline Registered User
    Location : north lincs.
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    Default Re: Volvo Engine Cooling System

    have you remembered to fit the rubber "seal" to the impeller, its like a 1p piece that pushes onto the impeller after you have fitted it.?

  10. #10
    aztec's Avatar
    aztec is offline Registered User
    Location : Poole Dorset
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    Default Re: Volvo Engine Cooling System

    i'd go for a pump/impellor fault or an airleak in the supply side above the waterline.

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