Johson 9.5 Cooling Question

[jchurley]

First, apologies in advance if this has been answered elsewhere, but all my search efforts have been in vain.

I'm in the process of rebuilding a 9.5 Johnson I picked up a few months ago. Not sure exactly of the year - the plate has been sanded, painted, sanded and painted again - but I think it's a 1967 based on the fuel pump, carb, and anti-vibration brackets.

Anyway, I'm in the process of trying to get the water flowing. When I replaced the impeller and pump housing I found out that the copper supply tube had slipped out of the engine block. After taking that apart I saw that it was missing the push nut, washer and o-ring. Ordered those along with gaskets and now am putting it back together.

I got the tube in place, exhaust housing back together, and the whole thing connected to the lower cover. I then tried to pump water up the copper supply tube but no luck - it drained down through the exhaust housing.

Removed the t-stat cover to find a rusty, gunky mess. Pulled the t-stat out and now when I pump water up the copper tube it does squirt out of the t-stat area, however some/most of the water still leaks down through the exhaust housing.

I put an inspection camera up through the driveshaft hole and confirmed that the copper tube is snug in place - no water leaks from there, so I'm not sure where the water is coming from. I do know that it is coming down the "inside" of the exhaust housing - around the boot and plate for the supply tube and shift rod.

Is this normal (like some kind of overflow if too much water is being pumped up the tube) or something I should investigate and fix before I put the other cover, linkages, etc. back on.

Sorry if I misused any of the terms - I'm not a mechanic.

Thanks all

Joe

 

[F_R]

First let me confess I'm not totally sure of the water route on that model. However, I think it would be safe to say that at least some water should be coming down the exhaust housing to keep it cool, but I'm not sure just how much. Another thing you say it is coming down around the boot. That shouldn't be. That boot needs to be sealed off from the exhaust to prevent exhaust gasses from getting out and smothering the engine. The area ABOVE the boot would be on the side of the coolant flow before it gets to the powerhead. Additionally, there are two large drain holes to drain off the water from that area that has gone up the drive shaft tube (escaped from the water pump)

Don't know if this helps at all or not.

 

[Vic.S]

There is some info which might be helpful on Leeroy's ramblings. http://www.leeroysramblings.com/OMC_9.5.htm

I don't know if you are expecting to see water from the outlet at the back of the casing below the cowling but water does not issue from here until the motor has warmed up and the thermostat has opened

 

[F_R]

There is some info which might be helpful on Leeroy's ramblings. http://www.leeroysramblings.com/OMC_9.5.htm

I don't know if you are expecting to see water from the outlet at the back of the casing below the cowling but water does not issue from here until the motor has warmed up and the thermostat has opened

With all due respect, that is a common misconception and untrue. Water should discharge within seconds after the motor is started. That is true because there are two water flow paths through the powerhead and one of them is not controlled by the thermostat, so water flows through that path at all times.

 

[Vic.S]

deleted

 

[Vic.S]

With all due respect, that is a common misconception and untrue. Water should discharge within seconds after the motor is started. That is true because there are two water flow paths through the powerhead and one of them is not controlled by the thermostat, so water flows through that path at all times.

Earlier you said you were not sure of the water route of this model.

LeeRoy says

Exhaust Water Indicator : This model doesn't have a overboard water indicator telltale "pee hole" like later models do. But there is a corrugated rubber boot hose(mentioned above) attached to the back of the engine block which comes out the back of the engine casing just under the cowling. You should be seeing a healthy broken-up water spray as seen in the running motor in the red trash can farther down in this article. At higher speeds, less exhaust comes out, so the water sort of runs out. Water mix will only spray out that hole when the thermostat is open. So until the motor warms up, it should be dry for possibly the first minute or so when started cold".

Now I don't know who to believe.

 

[F_R]

When I said I am not sure about the water route, I meant as far as how it is discharged into the exhaust housing. Believe whatever you want, it doesn't matter to me. But my references are that I was a full time outboard motor mechanic for 24 years, including in a dealership when that motor was built, and worked on lots of them. If it doesn't discharge water during the warm-up period, the thermostat bypass is plugged up.......or it isn't getting water from the pump.

Picture is from the Johnson factory service manual. Note the dotted arrows indicate the flow through the cylinder block, controlled by the thermostat. But the exhaust manifold is cooled all the time via the bypass. Yes they do use a generic drawing, but it is correct otherwise.

http://s19.postimg.org/todyivroz/9_5_water_flow.jpg

But what do it know.....