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  1. #1
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    Overheating Again

    Hi all, long time reader, first time poster. I'm at a loss, searched many posts, scoured the threads and cant find the solution. Had an '88 200 Carb for 20 years without an issue. This year new water pump housing , impeller etc maiden seasonal voyage today and I get an overheat alarm. For the time in the water, the temp came up pretty quick (quicker than ever) then as soon as I got underway I saw a steady increase in water temp @ 3000 rpm until the alarm reminded me that it was there. First time ever. Here's where I get confused; the telltale is pumping good water but it's hot probably in line with what the temp gauge is telling me. Temps remain high at idle in neutral but holding it at 3500 in neutral brings the temps back to normal with good flow. In gear and we revert to the overheat scenario. Dont know whether anyone else here has experienced this scenario but I'm baffled. WHY do I have an overheat problem in gear with good water flow and experience normal temps in neutral at the same RPM. Id be grateful for any advice.

  2. #2
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    It could be a stuck poppet valve.....Just something to check.

  3. #3
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    I agree with Dave
    When the last time the poppet kit has been changed?
    When u changed impeller etc , how did it look? Pieces missin?

  4. #4
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    Quote Originally Posted by Tocumwal View Post
    Had an '88 200 Carb for 20 years without an issue. This year new water pump housing , impeller etc maiden seasonal voyage today and I get an overheat alarm.
    That's where you need to look. And as you've discovered, telltales tell you almost nothing.
    Living in the Freedom provided by Bud Conner and his fellow warriors.
    R.I.P. my Heathen Brother






  5. #5
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    What is the water pressure?

    Dave
    1980 Cougar 19 tunnel,90 2.4L Bridgeport EFI in middle of restoration.
    1988 BAJA Sunsport 186, 96 225 Pro Max
    79 12' Auminum, 95 Merc 9.9
    RIP Stu
    "So many idiots, so few bullets"

  6. #6
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    OK, I will check it out

  7. #7
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    Poppet has never been changed, we do about 100hrs a season social waterskiing. The impeller gets changed every year, it was starting to get soft but was intact.

  8. #8
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    Thanks for all the replies, I'll check out the poppet, never had a need for a water pressure gauge, that's until now. For the first time ever I used an aftermarket kit for the pump and housing and this is the first year I've ever had a problem. Is it just a coincidence or have others had issues with non genuine

  9. #9
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    Quote Originally Posted by Tocumwal View Post
    Is it just a coincidence or have others had issues with non genuine
    I only use genuine but even with those I find variances with efficiency.
    Living in the Freedom provided by Bud Conner and his fellow warriors.
    R.I.P. my Heathen Brother






  10. #10
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    OK. Found the problem. For some stupid reason the grommet/seal in the pump outlet had collapsed and almost completely blocked the outlet after 6 attempts with dropping the box we diagnosed the problem, today I learned about the thermostats and poppets but now were good to go. Thanks for everyone's advice everything now seems to be in order. FWIW can now drop the box, replace the impeller and reassemble within half an hr, probably could do it blind. But all good thanks again to everyone.

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  12. #11
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    Thanks for coming back to tell us what the problem was. Nice when it is something simple, too.

  13. #12
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    A new Merc man is born..... The cranks chimmed in Merc heaven.

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