Water travel thru exhaust manifold

Having overheating problems when at idle,1984 "SN 2001", I have checked all fittings and impeller but still overheating. Was told that the exhaust manifold may be plugged up from years of use. I understand the water travel thru the engine but not the exhaust. Was wondering how the water dumps into the exhaust to go out the rear of boat and is he talking about the water jacket before it goes to the risers that may be clogged? Thanks

Obsessed can you explain the "bucket test"? The impeller in the RWP is new, so if it sucks all the water out of the bucket in a few seconds the pumps good and the problem is from the pick up to the water pump?

marmon77 wrote: Was told that the exhaust manifold may be plugged up from years of use. is he talking about the water jacket before it goes to the risers that may be clogged? Thanks

Who is "he"?? Whoever he is, it sure doesn't sound like he knows what he is talking about. If a "mechanic", find a new one! I agree with the others, Go looking for a air leak on the suction side of the RWP. You couls also have a bad shaft seal on the RWP allowing air.