Temp drops when I go above 3,000 rpm and alarm

[Adam small]

I have a 98 230 select with a 5.0 merc and bravo one 2nd gen outdrive . When I’m crushing 3k or under no issues as soon as I raise rpms the temp slowly drops from 170 down to 40 or 50 then and alarm goes off . As I let it idle or drive slow the temp increases back to normal . It appears there is a second pump impeller in the outdrive , is it possible that it can’t keep up with water pump on engine ? Bad thermostat or gasket . Any ideas please ? Motor only has 210 hrs on it and manifolds and risers only 3 years old and it runs great

 

[Little Ducky]

This is strange but I just had something similar happen to me this weekend with one of my 5.0's. I was on plane and humming around 4K rpm and the alarm goes off and I notice the temp gauge for one of my motors drops and then comes back up to 170. I turned everything off took a look checked all my fluids and then started it back up and didn't have any more issues.

When it cooled off a bit I checked all the wiring connections and they all seem pretty tight.

 

[scoflaw]

Bravo's don't have water pumps in the drive. Anyways, the only thing I can think of is that the engine is running out of water and the temp sender is in air not water.

 

[Adam small]

There’s no sea water pump

 

[scoflaw]

So you have an Alpha drive. So freshen up your pump.

 

[Adam small]

Do u think that’s what it seems to be

 

[scoflaw]

It's the right place to start.