Twin 454's. Even a midget couldn't get to the sea water pumps. Does the entire rear seat etc have to come out to get to them? Any tips???????Thanks, Mark

Had the same issue myself. I was fortunate and had to rip the back seat out to replace a bilge pump, so I took the opportunity to replace impellors and belts while I was in there. Guess this would be a good time to create a midget contortionist

Yes, the back seat has to come out or at least unbolt to push it foward so you can get a midget upside down with a wrench. My tip would be to pay someone to do it.

its designed for someone with 3 elbows to do it

you dont have to remove the seat,disconnect the batterys and remove the alternator and bracket and your there.

Its not easy but can be done, even by a fat man
Follow boatnt's advice thats how I did it as well.

Well Fellers, I appreciate the replies.......I took the seat back out and found the sea water pump impeller in perfect condition. I also back flushed the intake hose back thru the outdrive and back flushed the hose that goes out from the pump and up to the thermostat housing thru the cooler. Splashed the boat last Friday and it stays at 150 when going "coal barge" speed, but jumps up rapidly when I get up on top of the water.

I'm guessing a partial blockage somewhere......any suggestions???? Thanks

Possible blockage at the riser/manifold joint?

Double jointed mechanic would come in handy.

How could something get that far to cause a blockage unless some rust? Heck, I can't see how anything got past the impeller without damaging it. I'm assuming something (trash) got sucked in thru the intake because the water is full of crap...we've had record May rains. Also, I've got Imco lowers which have a large water intake along the leading edge. Backflushing did yield one small piece of wood...........

Mabe blockage at in the oil cooler?