4 Stroke cooling requirements

[Will S.]

I hit an area yesterday on the lower Long Creek where the water temp was 86 degrees. (air temp 98).

First I wondered why on earth was I on the water followed by when is the water too hot to cool an outboard sufficiently.

[Flysmallie]

Probably way hotter than any of our lakes will ever be. 

[fishinwrench]

When is the coolant in the radiator of your truck too hot to cool it?    

As long as the coolant keeps circulating you're fine.

[MrGiggles]

I agree with Flysmallie. 

You would need an engineer to give an accurate answer. At some point the temperature differential between the lake water and outboard would not be high enough for cooling to happen within the constraints of the outboards water pump and cooling system, as to how hot that is, there are way too many variables for a guy like me to figure out.

[bfishn]

Hmmm... since 4 stroke outboards have a thermostat that doesn't open till 150-160 degrees... 😏

[Will S.]

Just now, bfishn said:

Hmmm... since 4 stroke outboards have a thermostat that doesn't open till 150-160 degrees... 😏

Good point, I guess the water would always be cooler than that !

[Devan S.]

I have no knowledge what any internal component is likely to be running. I assume they would be at least or couple or more times hotter than ambient air or lake water. However @fishinwrench brings up the best point in that a cars system is closed and uses the radiator to remove latent heat from the system. You effectively have multiple points of thermal transfer(hot component to water, water to radiator, radiator to ambient)  Outboards are constantly pulling new water and therefore your coolant is effectively never building heat through multiple cycles. Once its through the entire system its pushed out into the lake fresh water at lake temperature is pull in. 

[Flysmallie]

3 hours ago, Will S. said:

Good point, I guess the water would always be cooler than that !

Let’s hope so. Either that or the fish will be ready to eat when you get them to the boat. 

[jdmidwest]

You only have to worry about waters  cooling properties when it gets stiff.  Winter is the time to watch out.  Don't want to freeze up the water intakes on a cold winter day.

 

[Bgctrading]

So... Are we heading UP the lake just a little bit with every boat??