hello new member here, please bare with me! im out of possible solutions with my first boat. I have a 1993 four winns 201 liberator with a 5.7 350 small block chevy. the outdrive is an King Cobra and has had this issue since I bout the boat. a mechanic has had it for over a year as of may and rebuilt the outdrive from ground up, yet still has overheating condition.
to help diagnose the problem myself, I drove the boat- finding that it only overheats once on plane. coming off plane the boat cools down to proper operation tempatures. to further narrow the problem, I put a clear hose from oil cooler to thermostat housing on top of block.
As soon as I hit 1800 rpms, the minimum rpm that the boat will plane on, I start to observe about 50/50 air to water being pumped from the outdrive to the engine.
when off plane when there is water behind the transom and the outdrive is submerged, the clear tube becomes solid water and operates normally. once boat is on plane and part of outdrive is above the water, it begins sucking air and thus overheats.
all pickups and O-rings visible when case is split have been checked and replaced. incredibly stumped here and desperate for help please! on my third impellor since I bought the boat.
P.S. the liberator has dual exhausts out both sides of boat, so there is no way it is sucking exhaust. thanks, Brandon
to help diagnose the problem myself, I drove the boat- finding that it only overheats once on plane. coming off plane the boat cools down to proper operation tempatures. to further narrow the problem, I put a clear hose from oil cooler to thermostat housing on top of block.
As soon as I hit 1800 rpms, the minimum rpm that the boat will plane on, I start to observe about 50/50 air to water being pumped from the outdrive to the engine.
when off plane when there is water behind the transom and the outdrive is submerged, the clear tube becomes solid water and operates normally. once boat is on plane and part of outdrive is above the water, it begins sucking air and thus overheats.
all pickups and O-rings visible when case is split have been checked and replaced. incredibly stumped here and desperate for help please! on my third impellor since I bought the boat.
P.S. the liberator has dual exhausts out both sides of boat, so there is no way it is sucking exhaust. thanks, Brandon