2002 Mercury Saltwater 150 Outboard External Water Pump?????
Ok, I know from the posts on here that I'm not the only one with this problem. I have to run in shallows and am constantly picking up trash in the cooling system. Specifically, the inlet to my poppet valve gets trash in it, gets partially blocked, and opens late. This results in a mid-throttle overheat conditon.
My first solution which will be tried as soon as my repair shop gets in yet another gasket set for the poppet assembly: I am going to try an inline water screen in the feed line from the top of the engine to the poppet. Hopefully I can catch the tiny oyster shell pieces before they make it into the poppet chamber. However, that really only solves that one restriction area. Stuff can still be picked up and stick in other places.
This leads to my second solution... Can I relocate my pickup? I cannot see a way to do this without relocating the water pump as well. However, this doesn't seem impossible. Hell, for that matter, it doesn't even look that hard. From a design standpoint, it looks fairly straightforward. (as well as 100% reversible should my design fail to perform)
1. Drop lower unit
2. Remove factory water pump/housing
3. Block off/plug water feed tube from water pump to powerhead (so I dont lose my water back into the sea thru the factory inlet)
4. Reinstall lower unit
5. Remove flush plug on back of engine
6. Remove check valve from flush line (mainly only if necessary, it may restrict too much as this was not designed to pass enough water for WOT operation)
7. Install thru-hull water pickup designed for an inboard. Obviously, this needs to always be below the waterline far enough to never ever suck air, but could be located so as not to pick up trash. Also, it would have a built in screen, which my motor does not.
8. Install an aftermarket-type electric water pump to pump water from the pickup, to the engine flush fitting. (You know the type, used on car engines for race applications.)
Here are the problems I foresee so far:
1. I am 80% sure the flush fitting puts water in at the right location (at the top of the water feed tube) This seems logical, as you are able to run the engine from this water supply to clear out the saltwater. However, if this doesn't work, plan B would be to drill a hole in the center section for a hose to 90 into and meet up with the factory feed tube.
2. Gonna have to find a self-priming water pump. Or mount the water pump below the waterline in the hull so it gravity-primes when I set the boat in the water.
3. Gonna have to choose the pump carefully to stand up to the saltwater for as long as possible. There's a plastic universal one on eBay for about $200.
4. I can conclude that this will not mess with thermostat operation much, but is almost certainly going to screw with poppet valve operation as the water pump speed and therefor, water pressure, will no longer be tied to RPM.
Any input? Anyone seen something similar attempted b4? Anyone think they wanna be there with a camera to watch a Mercury melt? lol