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Old 07-28-2009, 01:13 AM
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Bellinghamster Bellinghamster is offline
TT Enthusiast
Join Date: Apr 2008
Boat: 1978 Stars and Stripes, PCM 351 (60hrs)
Location: Northwest WA
Posts: 190
It looks to me as though those manifolds were set up for freshwater cooling. Engine coolant would circulate through the manifold in a closed circuit and raw water (exiting the heat exchanger) goes into the riser and out the exhaust. Most are "convertable" in that the only difference is the gasket used between the manifold and riser - raw water cooled has passages through the gasket and only one port for water to go in (at the front of the manifold). The water cools the manifold, goes up into the riser and mixes with the exhaust. Fresh water cooled uses a gasket that blocks the water passages between the manifold and riser keeping them seperate. If you were getting water in the oil from the manifolds it can be from them being rusted out, cracked, or a leaking gasket between the manifold and riser (I've had two boats that this happened to - one was a rusted through riser, the other was a bad gasket)
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