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Thread: Overheating

  1. #1
    Join Date
    Apr 2019
    Posts
    36

    Default Overheating

    Volvo Penta Kad32 been going great guns then recently we've been noticing water in the bilge.
    I put some luminous dye in the fresh water and it was leaking out the header tank.
    Did a 30mile run this morning fine, just the usual small leaking into the bilge...then this afternoon after chugging up the river and then giving it the beans it shat itself big time. Luminous green water pumping out the header tank and temperature gauge on red alert in a very short space of time.
    Have had troubles with overheating in the past which was a bunged up oil cooler but after stripping that off it seems ok.
    Thermostats appear good.
    No air locks.
    Impeller on raw water is good.
    No sign of water in oil
    Any suggestions????
    Cheers

  2. #2
    Join Date
    Dec 2005
    Location
    Live London
    Posts
    3,838

    Default Re: Overheating

    If the heat exchangers have not been cleaned out recently then they will need a flush with hydrocloric acid ( supermarket if you are in Spain e1 for 1.5 lt or eBay in U.K. )

    Remove or replace engine anodes as it dissolves them

  3. #3
    Join Date
    Feb 2008
    Location
    Farndon
    Posts
    3,047

    Default Re: Overheating

    The only few times I have had overheating on the river has been due to something picked up on the intake. After stopping the engine and letting it cool all has been well.

  4. #4
    Join Date
    May 2001
    Location
    Worcestershire/Pembrokeshire
    Posts
    2,392

    Default Re: Overheating

    pickup elbow on the outdrive?
    If its the alloy type they rot and break after a few years.
    Temps all ok at displacement speed as it's underwater but once on the plane then air rather than water is sucked into the cooling system and BINGO overheat.

  5. #5
    Join Date
    Apr 2019
    Posts
    36

    Default Re: Overheating

    Should have said this is a RIB. Got it back on the trailer and ran it in a tub and raw water side runs fine. Checked the elbow just inside engine bay where it picks up as we had the remains of a shredded impeller once but all clear. Nothing in the strainer.

  6. #6
    Join Date
    Feb 2008
    Location
    Farndon
    Posts
    3,047

    Default Re: Overheating

    An obstruction on the intake may have fallen off.
    Check the raw water pump is not worn internally . The brass face may be replaced inexpensively.

  7. #7
    Join Date
    Feb 2015
    Location
    Conwy
    Posts
    4,191

    Default Re: Overheating

    I had a problem a couple years ago where air was being sucked into the raw water pump from behind through the shaft and bearings. Not enough to stop the pump working at low speeds but at high speeds would suck in enough air to create an air lock. Didn't seem credible at the time but once again VolvoPaul was spot on the money.
    Annually I get another issue with similar symptoms. Barnacles and fouling grow in the intake ports of the leg. It doesn't take a lot of them either before they hit critical mass. As you are on a trailer this is probably not the case, but if you left your RIB on a mooring even for a couple weeks you'll be surprised how quickly the little critters can invade and grow enough to do this.

  8. #8
    Join Date
    Apr 2019
    Posts
    36

    Default Re: Overheating

    Quote Originally Posted by jrudge View Post
    If the heat exchangers have not been cleaned out recently then they will need a flush with hydrocloric acid ( supermarket if you are in Spain e1 for 1.5 lt or eBay in U.K. )

    Remove or replace engine anodes as it dissolves them
    Got that off and it's clean as a whistle..

  9. #9
    Join Date
    Apr 2019
    Posts
    36

    Default Re: Overheating

    Quote Originally Posted by tico View Post
    pickup elbow on the outdrive?
    If its the alloy type they rot and break after a few years.
    Temps all ok at displacement speed as it's underwater but once on the plane then air rather than water is sucked into the cooling system and BINGO overheat.
    I shall check it out thanks

  10. #10
    Join Date
    Apr 2008
    Location
    Isle of Man
    Posts
    2,104

    Default Re: Overheating

    Have you recently filled the coolant expansion tank?

    Certainly on early Kad42, the tank was under sized and would chuck out coolant for fun.

    Could be as simple as a coolant cap is knackered too.

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