Will hooking up a garden hose to exhaust manifolds give enough pressure to expose leaks? I have done this, but it did not leak. I have 3 cylinders on one bank looking brand new (never fired) on my new motor. I find it really hard to believe an intake or head problem would cause three cylinders not to fire.

The motor seemed to idle fine, but under any throttle cylinders would go dead. My guess is cylinders were swimming.

Why "guess" is there water in the cylinders or not? If there is a lot of water it will not run period. I have tried the water on a hose and it did not work for me. My problem was when it heated up it leaked from the riser gasket into the manifold. At high RPMS it would not bother it. IT loaded up at idle.

I would think a water hose will find the leak. You have 50-60 psi on a lot of water hoses. 15-20 with a max of 30 psi in the boat.

I forgot to mention, everything on the motor except the manifolds/risers is new, and intake and head gaskets looked kosher.

I think your right, its the gasket leaking when at temperature. Hard to tell that when you use a garden hose.

I've decided to get aftermarket exhaust, one without that infernal wet joint.

I just would like to find the actual cause of my problems

CMI uses external jumpers and avoids the internal joint all together!! Unitop or Etops would work great for your application.

See:

www.custommarine.com

Please contact us for your CMI Exhaust needs.

www.atecoengines.com