Open cooling system question

[Drcoffee]

Rinker 1995 Captiva 212 5.7 merc alpha 1 gen 2

had the boat out yesterday for first time this season. After doing full tune up, impeller, new bilge blower, and a dozen misc updates, it really runs out nice. Fires right up hot or cold.

my question is this. After cruising the lake and then shutting down, anchoring out to relax, I took a quick look around the engine. The fresh water supply hose to the circulating pump seemed to be pressurized. On an open cooling system is that even possible? If not, what would cause this?

 

[alldodge]

Rinker 1995 Captiva 212 5.7 merc alpha 1 gen 2
The fresh water supply hose to the circulating pump seemed to be pressurized.

What makes you think its pressurized?

 

[Drcoffee]

When I squeezed the large hose, it didnt compress much. much like when you check your cars cooling system. Maybe nobody has thought to check theirs, but it just seemed strange if the boat doesnt have a closed cooling system.

 

[achris]

As well as being quite stiff, that hose alway has an internal spring. That's why it is difficult to compress. It's not pressurized.

Chris ..

 

[alldodge]

There is no issue, there is a spring inside the hose to keep it from collapsing

 

[Drcoffee]

Interesting. Thank you. I took the hose off when I winterized it but did not notice it then. that makes sense, so the hose doesnt collapse under suction.