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Ok to patch manifolds?


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Well I've been waiting for it to happen and it finally did. I have a small (like the size of this o) hole in my right manifold. I obviously plan on replacing these soon but in the mean time I have a trip planned with the boat that's pretty non refundable. Will I be good to JB Weld over the hole? It's supposed to be good to 600 degrees and around 4000 psi of tensile strength so I'd imagine it would work? Any other suggestions?

Appreciate it

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martinarcher

Drill it round, tap it, put a bolt in it.

Mechanical>chemical

If it's that small - the drill and tap method might be the way to fly.

If you can't do that, my boat came with a JB Welded manifold. If it is prepped right it will hold.

If it drips no biggie...it's just a bit of water.

Edited by martinarcher
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Drill it round, tap it, put a bolt in it.

It's a cast part that is rotting (rusting) through. You're not going to be able to tap it. For a mechanical solution, you could pull the riser and put a small machine screw through the hole with washers inside and out and then nutted. I would just use JB Weld. Do it right though. Pull the rise off and JB Weld it inside and out. Wire brush the surfaces really well and wipe them down with acetone before applying the epoxy.

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martinarcher

What blows me away is my manifolds on both Bu's lasted over 20 years before showing signs of rust through. On his 06' he's got a hole? Is the boat ran in brackish or salt water?

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OP has't stated if he has the Monsoon or not. I've heard pinholes are not rare in the aluminum manifolds after five years or less.

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OP has't stated if he has the Monsoon or not. I've heard pinholes are not rare in the aluminum manifolds after five years or less.

The aluminum manifolds are still a cast piece, they're not machined (CNC'd). Though the metallurgic process is different (aluminum doesn't rust it corrodes) the result is nearly the same. The actual metal structure is "worn thin" until it fails. Cast steel or cast aluminum doesn't matter, he won't be able to drill and tap. The metal in the area of the hole will not be sufficient in thickness or integrity to have threads cut into it.

Not trying to be argumentative. Just don't want the OP to get his hopes up, or waste his time, on a fix that won't work.

Edited by NorCaliBu
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My friends 1991 Mercruiser motor ran with a cracked exh. manifold (OE Cast) for a summer. His JB weld held for half a summer before he jb'd it again. He missed draining the manifold the winter before. At the end of that summer the cyl. head on that side (w/cracked man.) dropped a valve seat/seal. Wrecked 2 pistons and scratched 2 cyl. walls. It had about 900 hours on it when it failed. The cracked manifold may have been a factor in the head failure. I don't know if it's happened to anyone else, but the old man mechanic said it could have contributed by causing a hot or cool spot on the head. I don't know. I would change those cracked manifolds before they do further damage.

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It is a 340 monsoon and is run in brackish to fresh water with an occasional day trip to heavy salt water (twice ever maybe)

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It is a 340 monsoon and is run in brackish to fresh water with an occasional day trip to heavy salt water (twice ever maybe)

That model has the cast aluminum one piece manifolds referred to as ETX manifolds which went into production in the 2004 model year. There are plugs welded into those manifolds that seal up the holes that are used to get the casting sand out of the manifolds at the foundry where they are made. Those welded in plugs are different alloy of aluminum than the manifolds are and are more electriclly "active" than the manifold itself. If those manifolds are exposed to an electrolyte ... salt water, brackish water or water with a high mineral content or in a location where there may be stray currents in the water and/or there are faulty or poor grounds in the boat ... those plugs will act like anodes and be consumed over time through electrolysis. Flushing with fresh water may help for the salt/brackish water users but that wont necessarily eliminate the possibility of electrolysis. The best thing to do with these manifolds is to completely drain them if the boat is going to be unused for more than a couple of days ... even if the boat is on a lift or on a trailer and not in the water. It is pretty simple to drain them as there is a quick drain hose that connect the manifolds together and has a garden hose type connector that you simply disconnect and let the water drain into the bilge.

The manifolds can be removed from the engine and taken to a welding shop where they can grind off the welds, remove the old plugs and TIG weld new ones in place. Indmar does have replacement plugs available that you can get through your dealer. Replacement ETX manifolds are also available. A third option is to replace the ETX manifolds with standard cast iron manifolds and risers. The performance loss will be minimal ... you may not even notice any change. If you fix the ETX manifolds or get new ones ... drain them after use as I mentioned above so the electrolysis does not reoccur.

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it's so great to have your contributions to the board.Yahoo.gif

thanks

That model has the cast aluminum one piece manifolds referred to as ETX manifolds which went into production in the 2004 model year. There are plugs welded into those manifolds that seal up the holes that are used to get the casting sand out of the manifolds at the foundry where they are made. Those welded in plugs are different alloy of aluminum than the manifolds are and are more electriclly "active" than the manifold itself. If those manifolds are exposed to an electrolyte ... salt water, brackish water or water with a high mineral content or in a location where there may be stray currents in the water and/or there are faulty or poor grounds in the boat ... those plugs will act like anodes and be consumed over time through electrolysis. Flushing with fresh water may help for the salt/brackish water users but that wont necessarily eliminate the possibility of electrolysis. The best thing to do with these manifolds is to completely drain them if the boat is going to be unused for more than a couple of days ... even if the boat is on a lift or on a trailer and not in the water. It is pretty simple to drain them as there is a quick drain hose that connect the manifolds together and has a garden hose type connector that you simply disconnect and let the water drain into the bilge.

The manifolds can be removed from the engine and taken to a welding shop where they can grind off the welds, remove the old plugs and TIG weld new ones in place. Indmar does have replacement plugs available that you can get through your dealer. Replacement ETX manifolds are also available. A third option is to replace the ETX manifolds with standard cast iron manifolds and risers. The performance loss will be minimal ... you may not even notice any change. If you fix the ETX manifolds or get new ones ... drain them after use as I mentioned above so the electrolysis does not reoccur.

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