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1977 70hp johnson

C

Ch@ppy

New member
I am wondering where the water comes out on this motor..... I have water that comes out from both the lower pivot arm and the upper pivot arm in addition to the lower unit exit ports..... I was told that this may be normal for this engine.....
 
The majority of the water is blown out the propeller exhaust area. However, the two holes at the rear of the engine, just below the powerhead..... explained below.
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(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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Thanks so much, that’s the best explanation I have read so far. Now that if I understand it correctly, the area around the outside of the exhaust tube fills with water and in my case there is no seal around the upper drive shaft where it comes through the adapter plate which is l letting excess water out.

Dose this sound correct to you?
 
There is no sealing area at the top portion of the driveshaft.

There is usually a sealing of sorts on top of the water pump that would prevent water from flowing up the driveshaft tube. Sometimes, for some reason, that is forgotten when installing a new water pump or whatever, and if so.... water would flow up that driveshaft tube and exit out the front of the top motor mount area.

That situation does allow water to be dangerously close to the top driveshaft splines and the lower main bearing seals... BUT... if the driveshaft splines have been thoroughly greased, and the lower main bearing seals are in good condition... the water won't hurt anything.

NO grease on the driveshaft splines would, in time, cause the driveshaft splines to rust/jam/freeze with the crankshaft splines in a welding like action which results in a stalemate/conflict in trying to remove the lower unit when needed. It is very important that the driveshaft splines be thoroughly greased whenever the lower unit is re-installed even if this water problem id non existent due to condensation.

Faulty lower seals and water in that area could allow water in #4 cylinder, however you would be warned about that immediately via a water fouled spark plug. <-- In my 30+ years at the bench, I've never seen this take place and this is just a "For Your Information" thing.
 
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