1992 40HP 2t Overheating

[Bill Riordan]

I think I have done everything possible and I can't solve this one, need some help.

Last year motor ran perfect all year, I had put a brand new impeller and pump housing in, no issues. This year the telltale is weak at idle, as soon as you put it in gear it stops altogether, a minute later it overheats.

So far I have:

1. Another complete new water pump kit, verified the channels in the lower unit are clear, yes the key is in and the rubber grommet that goes onto the discharge tube is in.
2. Taken off the head, exhaust cover and lifted the powerhead up to make sure everything is clear.
3. Tested the T-state in boiling water
4. When the lower unit is off if I connect water from the hose directly to the pump tube it flows out the telltale no problem so all circuits are clear.

HELP!!!! any ideas????

 

[brodmann]

When you replaced the new water pump with the second new water pump, did everything look good? Only 2 things I can think of. Are you able to make sure the meta tube is going into the water pump housing? Are you sure you're turning the crankshaft clockwise when putting it all together so it is shaped correctly? I don't mean to ask stupid questions, but that's all I can think of. Is it running hot in barrel, or on muffs or out in the river?

 

[Bill Riordan]

Valid questions, yes I have the impeller turning the correct way and I actually just measured the length of the tube to make sure it was going far enough down into the pump housing, everything looks good. For some reason this motor doesn't like muffs, that's how I cooked the pump two years ago, I back the trailer into the water far enough at the ramp so I can put the motor down and run it at it's normal water level, that also lets me put it in gear and see what's going on

 

[99yam40]

you said testing stat in boiling water, did you measure the water temp as you were heating it up to see when the stat opened.
boiling water is above when it should open.

also have you checked to make sure the dampener behind the water pump is in good shape to keep exhaust gases out of the water pump

 

[Bill Riordan]

If you are referring to part #24, yes it is new and installed properly

 

[99yam40]

no #2

 

[Bill Riordan]

Hmmmm, interesting, I had to go to the second lower unit fiche to even find that and I don't recall seeing it on the drive, at work and definitely look closely when I get home. What does it do? Not even sure where it goes, the fiche is very unclear.....

 

[99yam40]

here is a better view even tho it is not of your motor.
as I said earlier it helps seal off exhaust gases from getting into the water pump area

 

[Bill Riordan]

That would still be outside of the pump, would it not? probably a good idea from a maintenance perspective but how would it impact pump performance? I can't see how that would make the pump cavitate on the suction side or lose pressure on the discharge?

 

[Bill Riordan]

I am also really confused as to why flow almost completely stops when I put it in gear.....