Johnson 1973 85 HP 4Cyl Cooling/Water Tubes

[RDJuhl]

Hi,

I have been concerned about my engine cooling system. I replaced the water pump, and while the lower unit was off, I attached a water hose to the water tubes which extend down the exhaust housing towards the lower unit.

When attaching the water hose to the tube on starboard side, water easily came out where I removed the small hose near the vernatherm.

However, when I attached the water hose to the tube on the port side, no water would come out by the vernatherm.

Is this normal, or do I have a problem with the water tube on the port side?
I saw a sketch of the water flow elsewhere in the forum, but now am unable to find it. If anyone has it, can you attach?
Thanks for any guidance.

 

[F_R]

Re: Johnson 1973 85 HP 4Cyl Cooling/Water Tubes

One tube is for water going UP from the pump to the powerhead. The other tube is for water going back DOWN to the pump if the thermostat is closed. You can't force water UP the Down tube because it won't go past the check valve in the thermostat housing.

 

[RDJuhl]

Re: Johnson 1973 85 HP 4Cyl Cooling/Water Tubes

Great...that makes sense. Just to confirm...the port side tube would be the "down tube"?

 

[ezeke]

Re: Johnson 1973 85 HP 4Cyl Cooling/Water Tubes

Click the thumbnail.

 

[RDJuhl]

Re: Johnson 1973 85 HP 4Cyl Cooling/Water Tubes

Thanks for the thumbnail ezeke