Mercruiser exhaust manifolds

[rl4585]

Factory new GM marine 5.7 in 2013 new exhaust and risers @ that time. Don’t use boat much, probably doesn’t have 25 hours on it. In 2014 put closed cooling complete seakamp system and noticed I am always adding coolant to exchanger after a trip. After further review I found that I only had single gasket between exhaust and riser as opposed to two gaskets on either side of aluminum plate which Ive purchased and will be installing. It was suggested that I pressure check exhaust manifolds at this time. Note to readers: drain manifolds before removing risers you'll get water in your cylinders. I removed manifolds and made square steel plate with gasket to blank off riser surface. I installed rubber stoppers at drain t and top fitting. I filled manifold with water and blew air into where the drain cap was. The water bubbles out exhaust ports. The other one does it too. Then I tried the same thing on an 4.3 I had laying around same thing.. Can all these manifolds be bad? I have a feeling that a brand new one will do the same thing. Appreciate a little insight. Thanks in advance

 

[Bt Doctur]

not knowing exactly what your testing (regular manifolds and risers or dry joint manifolds and risers)and how your testing but if the exaust port where the elbow goes is closed off and the water exits the exaust ports where it connects to the engine the manifold is cracked or your plate is not sealing properly.
Another way to test is plug the bottom port and pour water into the channel at the top of the manifold ,not in the exaust port itself. If the exaust ports show wetness or visable water ,there leaking.