fuel pump, water line removal

i have a 1983 70hp , good motor over all but i was wondering if i can remove the water cooling lines that go to the fuel pump, to give the motor most available water possible. any ideas. i was also thinking about removing the thermostat. when i put rings in it it didnt have one and the motor was rebuilt once before so who ever did it must of had a reason but anyone familiar with these motor hit me up that would be great thanks

I rarely see a t-stat in these motors, and I've messed with a lot of them. Apparently Merc advised the dealers to remove the things since the motor has marginal cooling to begin with.

Yes, definitely plug that water line to the fuel pump. Its "stealing" water cooling the block needs, and it didn't do squat for idling.

Jeff

thanks but should i plug all four sides or just the main inleton the lower plate

also is there anywhere i would be able to install a temp sensor without doing any drilling

All you need to do is plug where the water comes OUT on the lower right side, in the middle of the power head. Be sure that the drain at the top of the block is open and spewing freely.

In the water jacket cover (spark plug area) there is a pipe plug where you could put a temp sensor.

Jeff

PS: Literally building a 70 hp yesterday and today.

when ur talking about spewing r u talking about the water discharger/pisser

The "Tell Tale". Right

Jeff

PS: One of these days (motors) I'm going to pipe that fuel pump water flow to the plug that's between the top and middle cylinders in the head water jacket. A bit more cool water here couldn't hurt!

ya i was gonna say, i think if i eliminate fuel pump water lines on these hot days im gonna go into vapor lock, local machnic told me as long as i put a impeller in it every year or two i should be ok

About 3.4 zillion outboards out there don't have that set up and don't have vapor lock problems, so... Always a good idea on changing impellers, especially on this motor.

On the size (under size, actually) of that motor's impeller, check out the photo below. The small impeller was fine for 40 hp twins and even 50 hp fours, but it was a bit under-sized for a 70 hp triple. Conversely, the giant impeller was too BIG for the smallest engine used in, the 65 hp fours. (The largest engine it went into was the 150 hp sixes.) They tended to run too cold, causing piston scuffing problems. The sawmill operators loved them, however! They ran forever shoving log floats down river.

Jeff