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9.9 HP 1974 Johnson not pumping water

C

code1p36

Regular Contributor
My 1974 9.9 wasn't pumping water so I pulled the lower unit and replaced the impeller which was actually in pretty good shape. Then I put a water hose with a reducer on it and place it up the water inlet tube and it slowly pressurizes and no water comes out of the back of the motor therefore telling me something is blocked nearby. I tried the reverse and put water up the outlet on the back side of the motor. Water does come out around the copper water inlet tube but not through the middle of it. I took a coat hanger and put up the inlet tube and it did seem a bit restricted but moves fluently now but still doesn't allow water to flow through it. I have heard of that rubber gromet at the top of the inlet becoming lodged or popping out. Is it possible to roto-rooter that gromet out of there with a coat hanger? I really don't feel like taking the powerhead off and replacing that if I don't have to. Any info would be appreciated.

Thanks.
 
The exhaust relief holes at the back of the engine just below the powerhead are not a water outlet passageway. They are an escape route for the exhaust when the engine is in the water. However, water does sometimes exit at that location as explained below. Water does not exit that location simply by forcing water up the water tube..

(Exhaust Relief Ports - Exhaust Housing (Inner/Outer)
(J Reeves)

The long housing between the powerhead and the lower unit is called the exhaust housing. There is a inner housing within it that has a heavy duty seal around the bottom of it, or heavy duty seals around a inner extension between the housing and the lower unit.
The red hot exhaust travels down thru that inner tube and out the propeller with a somewhat supply of water to cool the propeller hub. A good amount of water surrounds and fills the space between the outer and inner tube, otherwise the outer housing would get so hot that the paint would burn off.
Some water pumps, for some reason (differing even when new) exert a great amount of water pressure, and if the exhaust housing seals are in perfect condition, the water fills the tube to a point of overflowing.

This brings into play those two holes or slots, whichever the engine might have, at the top rear portion of the exhaust housing just below the powerhead.

Now, if those two holes/slots weren't there, water would continue to flow up into the cylinders. Water not flowing out of those holes is no concern for alarm UNLESS that outer housing suddenly becomes extremely hot..... the warning horn should sound long before that happens.
The main reason for those holes being there (exhaust relief holes) is that when at an idle, there is an extreme amount of resistance encountered by the exhaust trying to escape due the fact that the outlet via the propeller is now blocked by a wall of water. The escape route in this case is for the exhaust to escape out those two holes, otherwise the engine would slow down quite quickly and die. If exhaust cannot escape, air/fuel cannot gain entrance to the engine.

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NOTE: If that upper water tube grommet is faulty, remove the powerhead as it's not that complicated. Just take your time.
 
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You may have to take off the power head and replace the upper grommet on the water tube even if you do not like the idea.
it may work to put a curtain spiral in a drill and try to 'open' the grommet, but it may even be corrosion on the exhaust tube leaking water out.
Lifting the power head is not that tricky, but quite often the screws brakes that holds the exhaust tube!!
 
If your motor has a hose on side of motor for your water to spray out it may be stoped up.
I have also seen where dirt dobbers have stop up exhast port and side spray hose to the point I had to pull motor to clean water jacket channel.
Note does not take too long to pull motor to be shure and it is not all that difficult to do.
 
Thanks for the info Joe! I am going to see if I can carefully unblock that with a curtain spiral and drill. If that doesn't work I will have to look at taking off the powerhead. Should most of the water be exiting out the prop and a small mist out below the powerhead?

Thanks.
 
Did the 74 models have a " pee stream " or " telltale " -----------or is this something that came out on later later models ???-----------The early 9.9 motors did have some issues with carbon blocking the exhaus adapter.---------Time to go thru the motor and pull the powerhead, it is not that hard to do.
 
It has a telltale. So does this mean a small amount of water will come out of there and the rest will be coming through the prop?
 
The early 9.9 and 15 hp didn't push much water out the exhaust relief. Is the motor running hot? If it's not, I wouldn't mess with it. 77 or 78 was the first year for the tell tale stream.
 
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