SeaRay 220cc 1978/gm305 temperature behaviour

[sarantis]

Hello everybody,
I have new thermostat,new thermostat housing ,still i don't Know if the temperature is ok.With the thermostat out ,the needle at idle in gear it just passes the yellow region(the first small box) and at 3000 rpm it hardly reaches the center.With the thermostat in ,at idle in gear, the needle is at the center,at 3000 rpm it slightly passes the center but when i slow down the needle aproaches the red region for a while and a few minutes later it returns to slightly more than the center.Supposing the temp sender and the gauge are good may you tell me if the behavior of the gauge sounds ok to you?Thanks in advance.

 

[sarantis]

Re: SeaRay 220cc 1978/gm305 temperature behaviour

I forgot to mention,new impeller,new manifolds,new elbows

 

[Boomyal]

Re: SeaRay 220cc 1978/gm305 temperature behaviour

I take it that your temp guage does not have degree calibrations on it? I would buy a handheld infrared thermometer. This will enable you to check the temps at every part of your motor at every stage of operation. Google them. They are all over the net. No tool kit should be without one.

 

[Haut Medoc]

Re: SeaRay 220cc 1978/gm305 temperature behaviour

Yep, mine does the same.....
Keep that thermostat in, you should be running a 143* on a standard cooling system.......
The temp rises when you slow down because of reduced flow from less rpm's......
Pefectly normal!.......​

 

[Boomyal]

Re: SeaRay 220cc 1978/gm305 temperature behaviour

Yep, mine does the same.....
The temp rises when you slow down because of reduced flow from less rpm's......
Pefectly normal!.......​

Hmmmm, must be that puny little excuse for an impeller that the black anchors use. My OMC impeller is probably 3 times bigger and once the engine reaches the thermostat temp it stays rock solid at both idle and WOT.

 

[Don S]

Re: SeaRay 220cc 1978/gm305 temperature behaviour

Hmmmm, must be that puny little excuse for an impeller that the black anchors use.

With a good impeller and pump housing, and things aren't all plugged up somewhere, the Mercs also stay rock solid.
He has a cooling problem to find. Good news is, it's not white (aka OMC).