gents, I noticed the exhaust clappers are always partially open. will they function as designed and close when water is forced in from the rear? or should i replace them? I have a water in the oil problem and am wondering if this could be the cause. i have pulled the engine and removed the heads( rust in No. 8 cylinder) all gaskets are like new. the risers were plugged almost solid with rust and scale could this cause water to back up through the manifolds?