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  1. #1

    Join Date
    Oct 2012
    North Jersey

    3d exhaust melting / scored cylinder

    I have a 2004 3d with the 787. Supposedly had a rebuild winter before i bought it, very low hours since purchase - maybe 2 actual riding hours the more i think about it. T fitting in the exhaust melted and machine was choking off (poss from smoke?) after 10 minutes. Engine mount is also broken. During diagnosis, cooling water was flowing properly, compression was at 160 and 163lbs and all engine and exhaust temps seemed "normal". With the exhaust manifold off, independent dealer tech noted deep scoring in rear cylinder, recommending a rebuild. He thinks that oil getting into the cylinder caused the smoke choking off the engine. No cause for the melted exhaust T has been identified. Q1 - Does anyone with experience here have an idea about what caused the heat and melting? Q2 - Could a loose engine prevent water from cooling the exhaust somehow? Q3 - Does the scoring necessitate a rebuild if the compression is good? Q4 - Does a rebuild or reman replacement make sense if the cause for the melting isnt identified? Q5 - What can i sell a machine in this condition for? Is a $750 -$1000 sales price unrealistic? Im in North Jersey. Q6 - Can the cylinders be replaced without removing the deck? Q7 - Can the engine be removed through the access hole, or does the deck need to be removed?

    Yes, scrapping it is on the table. Just trying to do some research here. I cant find any posts answering my questions.


  2. #2

    Join Date
    Apr 2018
    Pearl River, LA
    Do NOT rebuild that engine yet. Do a compression check. You said you had a TEE fitting. Has your exhaust rave valve been removed and a fitting installed? Pictures would be great. I am also on the Seadooforum. That engine is NOT causing the exhaust to get hot. I suspect you have a restricted exhaust flow into the exhaust system. I always check my system by blowing some low pressure air through the cooling water system. I have a decent amount of experience with those model GTXs. I spend lots of time with my head in the engine compartment and I've had my share of mysterious problems. LOL PM me on the Seadoo forum. Take Care and good luck.

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  3. #3
    Myself's Avatar
    Join Date
    May 2007
    North Central Arkansas
    Most common causes on a 787 for melted exhaust parts are pisser lines on exhaust backwards or a bad regulating valve on the waterbox.

    If the compression is still it. 787's are tough.

    Make sure oiling system is working and check spark plug color after a 10 minute ride.

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