Exhaust leak!!!!
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Exhaust leak!!!!

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    Senior Member californiadreamin's Avatar
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    Default Exhaust leak!!!!

    Headed out to the lake two weekends ago and i was hearing a real light ticking sounded like an exhaust leak on the left side.
    Went out again yesterday and it got much worse. Ive got thru transom logs and snails. Bolts are tight. I refaced the manifolds two
    seasons ago when i rebuilt the motor and its got the fel-pro gaskets. These manifolds just want to warp between the bolts and leak!!
    What the hell can i do?

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    Senior Member californiadreamin's Avatar
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    455...iron heads

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    Senior Member jetboatperformance's Avatar
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    Quote Originally Posted by californiadreamin View Post
    455...iron heads
    Olds Wet Logs no matter who makes them will eventually warp , crack , sag and distort, this is due in part to the "siamese" designed center exaust ports What seems like an obvious "fix" (machining them) is unfortunately a temporary fix as the thinner (on the flanges) they will unfortunately re-distort again one thing that can help but cant always be a "field fix" is to have the exaust side head surfaces machined , IMO the best you can do is to straighten them, re gasket them with a good header gasket and use a thin coating of high temp silicone on both the head and manifold surfaces , keep them evenly tightened , also doesn't hurt to open up the snail exits tio 3.5 if this is an option call if we can help Tom

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    Senior Member californiadreamin's Avatar
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    Quote Originally Posted by jetboatperformance View Post
    Olds Wet Logs no matter who makes them will warp , crack , sag and distort, this is due in part to the "siamese" center exaust ports What seems like an obvious "fix" (machining them) is unfortunately a temporary fix as the thinner (on the flanges) they will unfortunately re-distort again one thing that can help but cant always be a "field fix" is to have the exaust head surfaces machined , IMO the best you can do is to re gasket them with a good gasket and use a high temp silicone , keep them evenly tightened , call if we can help Tom
    that makes sense...so id be better off leaving the manifold as is? what kinda gaskets? im looking at some embossed copper gaskets??
    any silicone you recommend?

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    tintingsandiego krusn56's Avatar
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    High temp red rtv and a good set of felpro. I dont think the copper will work with the log. I tried that years back on my olds/ford. Had good results with the blue felpro.
    Last edited by krusn56; 04-30-2012 at 08:47 PM.
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    Senior Member jetboatperformance's Avatar
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    Quote Originally Posted by californiadreamin View Post
    that makes sense...so id be better off leaving the manifold as is? what kinda gaskets? im looking at some embossed copper gaskets??
    any silicone you recommend?
    Quote Originally Posted by krusn56 View Post
    High temp red rtv and a good set of felpro. I dont think the copper will work with the log. I tried that years back on my olds/ford. Had good results with the blue felpro.
    Krusn answered both your questions , not a fan of copper on logs , like the silicone asbestos if available and we use orange and red hi temp when neccesary Tom

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    Senior Member wolfie's Avatar
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    Quote Originally Posted by jetboatperformance View Post
    Krusn answered both your questions , not a fan of copper on logs , like the silicone asbestos if available and we use orange and red hi temp when neccesary Tom
    I need to try that on the next boat. I used the copper on the cruiser. Held pretty good until the bolts loosened up. Tightened the bolts and no problem.

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    Senior Member rvrskir's Avatar
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    Weird we have the same boat and i too found an exhaust leak the last time out. except i found the crack in my exhaust manifold.
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    Canoe Jockey Michael Thomas's Avatar
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    I think logs are just prone to warpage. I have tried everything and came up with something that seems to be working. Stud the heads, use aluminum nut/washer combo from blower studs and cut the flange with a saw between the ports
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    Default aluminum logs

    per all the research i have done...a few years back...

    all aluminum logs, from the Factory (IE who ever marinized the motor)....Don't use gaskets...just high temp silicone!!!

    when aluminum logs fail is when someone uses gaskets!!! likes to bend the ears...

    i surfaced mine(455 olds), siliconed them, worked awesome for years...they were hard to get off when i pulled them to put the headers on i currently run...........

    just my 2 cents......
    i would really like to hear from Tom on this...i thought he was one of the people that helped me....

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    tintingsandiego krusn56's Avatar
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    If you have a 460 with thru bolt logs...you can run em with felpro. They are the only and best style log for a ford. No warp, leak and can tighten down without the use of silicon.
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    I agree with Krusn, BBF bolt through are the best, I have refaced and replaced (with used of course) BBF logs and they are a pain, plus u get to use a wrench only to remove the bolts, moral of the story find logs with as much meat as you can. I have no idea what is out there for BBO.

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    Quote Originally Posted by californiadreamin View Post
    Headed out to the lake two weekends ago and i was hearing a real light ticking sounded like an exhaust leak on the left side.
    Went out again yesterday and it got much worse. Ive got thru transom logs and snails. Bolts are tight. I refaced the manifolds two
    seasons ago when i rebuilt the motor and its got the fel-pro gaskets. These manifolds just want to warp between the bolts and leak!!
    What the hell can i do?
    Passing along this "fix". It helps to prevent distortion/warping on the siamese port on the Olds log. The photo shows the basic set-up. It's a piece of 1" wide by 1.5" tall aluminum barstock that I attached to the top of the log with a clamping arrangement. I filed the top of the log down a little to get reasonably good contact with the aluminum barstock piece. The barstock is through-drilled (0.50" dia.) and tapped on each end for 1/2" NPT barbed nipples. The water through-hole is offset (centerline is 1" away from the side that sits on the log port) to provide additional thread engagement for blind-drilled 1/4-20 tapped holes on the bottom side of the barstock piece. 1/4-20 bolts (or threaded rod) go on either side of the siamesed exhaust port, into the blind-tapped holes, to clamp the barstock piece on. There's a thinner piece of aluminum (or stainless) barstock that spans the siamese port on the backside to complete the clamping hardware. It has two 1/4" (clearance) holes in it for the 1/4" bolts/threaded rod.

    The whole contraption goes on/comes off pretty easily. Ran this on a set of logs for almost 20 years with negligable distortion/suck-in. You could use some heat transfer compound to increase the conductivity between the barstock and the port, but I didn't. I ran the water through these first, then the logs, then into the engine.

    Other: Don't use the siamese port exhaust bolt to attach the manifold. It'll just dump unwanted heat into the aluminum. Use RTV instead of exhaust gaskets.
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