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Thread: Exhaust leak on a 25 ZX?

  1. #1
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    Exhaust leak on a 25 ZX?

    Yesterday I was taking a look at my engine as it was warming up and noticed a very small amount of smoke or exhaust coming from under the port side exhaust manifold? I recently had the compression tested and serviced and new plugs installed, so the boat is running pretty well. The engine is a stock 502mpi with corsa silent choice exhast and low hours on the motor. I am wondering if there may be a small crack in the manifold? If there is a crack and I need to replace the manifolds, what would you recommend for a replacement? Since it is a stock motor, should I just replace with stock manifolds? Or would it be worth it to get some nicer headers or some EMI manifolds? At this time, I don't really plan nor do I have the cash to throw a ton of money into the motor. But if I can get some extra noticable power out of nice manifolds I would consider. Anyways, I would appreciate your thoughts on this. Like I said, it was a very small amount of smoke. Hardly noticable unless your face is right on top of the manifold.

  2. #2
    mrfixxall Guest

    Fixx

    Quote Originally Posted by Mckillop View Post
    Yesterday I was taking a look at my engine as it was warming up and noticed a very small amount of smoke or exhaust coming from under the port side exhaust manifold? I recently had the compression tested and serviced and new plugs installed, so the boat is running pretty well. The engine is a stock 502mpi with corsa exhast and low hours on the motor. I am wondering if there may be a small crack in the manifold? If there is a crack and I need to replace the manifolds, what would you recommend for a replacement? Since it is a stock motor, should I just replace with stock manifolds? Or would it be worth it to get some nicer headers or some EMI manifolds? At this time, I don't really plan nor do I have the cash to throw a ton of money into the motor. But if I can get some extra noticable power out of nice manifolds I would consider. Anyways, I would appreciate your thoughts on this. Like I said, it was a very small amount of smoke. Hardly noticable unless your face is right on top of the manifold.

    seems you just had the tune up done i would suspect a loose sparkplug..it will run fine until the plu blows out..i would grab ahold of the plug boot and see if the plug wiggles..or run a spark plug socket over them and snug them up..

  3. #3
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    Thanks, Ill check that first.

  4. #4
    mrfixxall Guest

    Fixx

    Quote Originally Posted by Mckillop View Post
    Thanks, Ill check that first.

    If the exhaust manifold was cracked their would be water coming out of it to..if the sparkplugs are tight then you may have a manifold gasket going out but it would usually make a popping noise which would be a exhaust leak between the cylinder head and the exhaust manifold..

  5. #5
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    With a stock engine don't waste your $$$ on headers, you need some fairly serious mods to gain anything. Many of our group have been disappointed!
    No matter what your beliefs are "GOD BLESS AMERICA"

    Fully retired marine tech near 60 years in the biz.

  6. #6
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    Good exhaust is a nice mod. Like Phil said, you won't notice much other than some bling and a little more throttle response. If you plan to build the engine up, it is a must and a great first step though.

    Try Fixx's stuff first.
    2001 35 Fountain Lightning w500 EFI's
    1973 X-18 - Merc 383 Magnum
    1974 Chris Craft Roamer with 1271 TI's

  7. #7
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    Thanks for the responces. I got into the engine compartment and gave a good look.(It sure is nice having that much room compared to my 18C) Thankfully I don't have any fluid or rust stains comeing out from around the manifold or risers, so at least I don't have to worry about that. I'm thinking it might have been a little oil on the engine that was burning off. Like I mentioned, it was just serviced so there is still some resedue on the block.

    As far as upgrading the manifolds and risers, thanks for the advice. I may keep my eyes out for a nice used set, but it doesn't sound like it would be worth spending $2K-$3K at this point.

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