Boat runs warmer in warmer water and hot weather

[Begester]

I recently moved from the Seattle area to the Charleston area and noticed by boat runs about 20 degrees warmer, is this normal? The water temperatures went from the mid 40?s to the upper 70?s and the weather is hotter here but other than that nothing has changed. Boat runs excellent, oil pressure is right where its supposed to be, the temperature gauge is just showing higher. Is this normal? I noticed also that the temperature goes down a little bit when I am going slow (about 1000 rpm) and goes up again when I?m cruising at ~3000 rpm.

I haven?t done anything yet but wanted to get some insight before I changed anything to see if this is normal in hotter climates. Boat is a 1989 SeaRay 220DA with a 5.7 liter Merc and freshwater exchanger.

Any insight is greatly appreciated.

 

[Alumarine]

What temps was it running and what's it running now?
Just to be clear, does it have a heat exchanger or not? Does it have a place to add antifreeze?
Or does 100% of the cooling come from the lake?

 

[Begester]

It was running religiously at 145 degrees, now its about 165. Yes, it has antifreeze and an exchanger.

Thanks for the help.

 

[Eric 3.7LX Alpha 1]

How old is the impeller in the drive?

 

[Begester]

impeller and water pump replaced at the end of last season and have maybe ~15 hours on them.

 

[joetheis]

I'm gonna take a stab at this.
I would ASSUME, if the water being pumped into the exchanger is warmer, it can't absorb? transfer? the heat from the engine coolant.
Last year I dropped my cuddy with a new engine in the St.Lawerence River in April. It ran 155-160, water temp 40 ish. In July it ran 165-175, water temp @ 60. This is a raw water cooling system, a bit different than yours but the idea is still the same.
I bet the water in the Sound was 20 cooler than where you at now? (or close).
Like if you take a cup of HOT coffee out in the winter it takes a few minutes to get cold, but summer time takes longer..........
Maybe?
Joe
always take any advice I give with a can of COLD beer er 2

 

[Begester]

Thanks for the insight. I was kind of thinking the same thing, especially since the water is at least 30+ degrees warmer here in South Carolina than it was in the Seattle area. The outside air temperature is also hotter so I'd also have to believe that my engine compartment is a little hotter as well.

Its interesting the things I've learned with this boat. Thanks again for the insight...glad I'm not the only one who has seen this phonemenan.