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  1. #1

    Default mercruiser y pipe

    I have a 1990 alpha one gen one with a 5.7. I pulled the motor to change the transom assembly (loose gimbal ring), I found a mint transom assembly I was going to put on but it has non-symmetrical holes for the y pipe. Mine has symmetrical holes for the y pipe. My y pipe is junk, can I find a y pipe to fit this transom assembly that will work with the rest of my exhaust system? Thanks

  2. #2
    Supreme Mariner Haut Medoc's Avatar
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    Default Re: mercruiser y pipe

    Doubtful.....
    You need to ID what the new one is from.....
    Disclaimer!: In my inexpert opinion......

  3. #3

    Default Re: mercruiser y pipe

    Just wanted to add 3 ot of the 4 holes line up on my y pipe, but its probably a no-no just to use 3.

  4. #4
    Rear Admiral Fishermark's Avatar
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    Default Re: mercruiser y pipe

    Actually, my boat came from the factory with a mis-matched transom assembly / y pipe combination. The non-symetrical holes are designed for the single pipe versus the y pipe. I called Mercruiser about it and they said it is no problem to use just three bolts. Surprised me, but it seems to be fairly common for the boat dealers to use whatever transom assembly they have laying around. Here's a pic of mine I removed which was original with the boat:

    (Ignore the red note - that was for another post!)




  5. #5
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: mercruiser y pipe

    Since the Y pipe connection is below the water line when the boat is in the water, I sure as 'ell wouldn't want just 3 bolts holding my Y pipe in place. I've had to replace a bunch of Y pipes because one of the tabs broke off and was allowing water in the boat. The tab was broken off the Y pipe, but no hole into exhaust passage. It just wouldn't seal with 3 bolts.

    I'm loosing respect for Mercruiser even faster than normal if that is the kind of information they are giving customers on the phone.
    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.

  6. #6
    Rear Admiral Fishermark's Avatar
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    Default Re: mercruiser y pipe

    As I said, it surprised me too. But that is the original transom assembly for my boat which came from Sportcraft with a 305 V8 engine and this transom assembly designed for a single pipe. When I bought my Mercruiser crate engine back in 03, I spent a lot of time on the phone with Mercruiser asking various questions, (and that's when I joined Iboats as well. In fact, I think I asked this very question myself back in 03), and that was one I posed to the tech. Now it could be he was speaking for himself and not Mercruiser. But he was their tech.

    Having said that - I've had no problems with leakage in that area for over five years now.

  7. #7
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: mercruiser y pipe

    Sometimes it's better to be lucky than good.
    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.

  8. #8
    Rear Admiral Fishermark's Avatar
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    Default Re: mercruiser y pipe

    Out of curiosity, and just to refresh my memory, I did a search of the archives and found the post I had a few years ago. Here's the quote from Mercruiser via email:

    Well, here's the final word from Mercruiser. Their initial response to my question was this:
    Quote:
    Thank you for your recent inquiry. The sterndrive and transom assembly do not change regardless of the model of the engine. The setup on the transom side is either for an Alpha assembly or a Bravo assembly. The "Y" pipe setup needs to be the approved exhaust application to work with your 5.7L and Bravo sterndrive. I cannot authorize the use of only three bolts when four bolts was the original planned design. MerCruiser recommends making any necessary changes to insure that both top bolts do line up and attach accordingly. I hope this information is helpful and please let MerCruiser Consumer Service know if we can be of further assistance.
    After writng back with a reminder that my boat doesn't have a Bravo drive, but an Alpha one, (as I had originally said!), I received the following response back:

    Quote:
    I spoke to a technical expert in the MerCruiser OEM department about how that should bolt up. He said that on some applications that you will only be able to access three holes to complete the assembly. It is completely normal and an approved method. That is officially MerCruiser stance. Sorry for any confusion.
    So there you have it - straight from Mercruiser. I guess it's okay to only use the three bolts for the "y" pipe after all!
    Here's the link to see the whole thread:

    http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/y-pipe-connection-question-46559.html


    It's ironic, that the one thing I DID remember wrong, is that the assembly I bought has the correct bolt hole arrangement for the V-8 y pipe. I guess it's been awhile since I stuck my head down there to look at what is currently on my boat.

  9. #9
    Rear Admiral Fishermark's Avatar
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    Default Re: mercruiser y pipe

    By the way, in case anyone does look at the link posted above - the leak I had at the transom area turned out to be a rotten transom. I had the transom rebuilt and have not had any problems since.

  10. #10

    Default Re: mercruiser y pipe

    Thanks for the info ,I guess mine will only get 3 bolts.

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