15hp not pumping water when in gear

Hey guys,

Here's my problem: in neutral my motor pumps plenty of water at idle and at higher revs.
When i drop her into gear she still pumps a reasonable amount of water at idle, however when i give her some juice and she comes under load the spray of water slows down to a trickle and the motor starts getting hot very quickly.

Impeller was still good however i have replaced anyway. thermostat is fine too. squirted water up the water tube and there was no blockage.

So where do i start looking? Head gasket?

Thanks

Adam

Re: 15hp not pumping water when in gear

What motor are we talking about here?

Re: 15hp not pumping water when in gear

When you are putting it "under load", is the motor in the water deep enough to cover the cavitation plate? Also check the water inlet port for blockage.

Re: 15hp not pumping water when in gear

oldcatamount said:

When you are putting it "under load", is the motor in the water deep enough to cover the cavitation plate? Also check the water inlet port for blockage.

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This is the first check for certain and often the only problem. However if water level is not the issue then the likely suspect is the water tube grommet at the top of the tube where it connects to the base of the motor. These go bad and your symptoms are in line with what happens. You should always post the year make and hp of your engine. Best of luck. Rick.

Re: 15hp not pumping water when in gear

Sorry, double post. See below.

Re: 15hp not pumping water when in gear

Need to know the year of the motor to determine if you have a tell tale or just an exhaust relief on the back of the midsection. On the 1974 to 1976 series, what you describe is almost normal since the t-stat, opening and closing will change the amount of water you see out the exhaust relief, as well the amount of pressure the water is pushed with (higher and lower RPMs) will direct more or less water out that exhaust relief. More pressure usually means less water since the angle of it changes with more pressure, and therefore less hits the exhaust relief hole.

If the motor is later then 1976, then what you describe is not very normal. So let us know

Re: 15hp not pumping water when in gear

Sorry Guys,

Managed to screw up already. motor is a mid 90s tohatsu.

Mods, Could you please move to the correct forum?

Anyway the motor has plenty of water over the intake.

Thanks for all your help so far

Re: 15hp not pumping water when in gear

Are you running it on muffs or in a tank? If in a tank, then as said before, you may be low on water & when you put it in gear, it blows the water rearward, starving the water pump intake.