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  1. #1

    Default volvo heat exchanger

    i have a 1985 bayliner 4cyl volvo engine with volvo penta i/o. Can anyone please tell me how does a heat exchanger work? Like give me a website, or an article about heat exchangers. When i turn on the ignition for a while it over heats, but its not on the water its in front of my house. Is this why it overheats? Im wondering its overheating because it is not running in the water? thats why i want to learn more about heat exchangers? My dad is a mechanic, and he wants to know how the cooling system works, so he can fix it. Any websites or articles would definity help. thx

  2. #2
    Chief Petty Officer
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    Default Re: volvo heat exchanger

    Do you know how a radiator in a car works? Its very similar to that except its a water to water exchange instead of an air to water.

    Do you have muff's hooked up to the outdrive when you are running the engine at your house? If you do not then yes, this is why it is over heating. The water from the lake cools the engine. The water from the lake passes through the exhanger and cools the coolant thats running through the block.
    1990 Stardust
    -Dual Chevy 305's with Volvo DP's

  3. #3

    Default Re: volvo heat exchanger

    thanx alot jeepster...thats what i needed. i didnt had the water running thru the muffs, thats why it overheated...thankyou!!!!

  4. #4

    Default Re: volvo heat exchanger

    It goes the same for the ocean too right?

  5. #5
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    Default Re: volvo heat exchanger

    You'll need a new impeller if you've been running without muffs. You need to have the muffs on at all times when running!!!

    The impeller is up front in the small round brass housing. You can get the impeller here on Iboats or at a local dealer or even an aftermarket impeller from Napa. You need to know the engine model number. If you know the engine model AQ125 or aq131 or ..., you can download manuals.
    '88 Baretta Success 200
    Volvo Penta AQ260/275

    '96 Weeres Suntanner 24
    '01 90hp Johnson

  6. #6
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: volvo heat exchanger

    Quote Originally Posted by layzeeboi View Post
    It goes the same for the ocean too right?
    Yes, ocean, lake, river, whatever the boat is setting in. aka Raw Water

    Along with burning up the impeller when running with no raw water to the engine (muffs), you may have burned the inside of the big hoses that hooks the exhaust manifold to the exhuast pipe. The water keeps them from burning. When you replace the impeller, you will need to find all the broken blades of the impeller.
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  7. #7
    Petty Officer 3rd Class tbear1964's Avatar
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    Default Re: volvo heat exchanger

    Here are some pics of an '83's impeller housing, for reference. AQ125A. Yours will be similar
    Attached Images Attached Images


    Some Beach Too
    1985 Cobalt Condesa
    5.7L/Alpha One

  8. #8
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    Default Re: volvo heat exchanger

    If you go back to the beginning of this section you'll see an "Adults Only" thread and an "Information for DIYer's" section. Look through those to find a manual for your engine. The manuals aren't tutorials but will go a long way toward getting a better idea of how things work.

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