Overheating??

[SloBurn]

My 94 270 Dancer temp gauge will go from 150 (normal) down to 100 and back up to 150-170 with in 3 seconds, sometimes it bounces higher and sets off my high temp alarm. Already replaced Sea water pump and impeller, thermostat, risers. Now I'm thinking sensor is NG?? Any suggestions?

 

[Skybolt]

My 94 270 Dancer temp gauge will go from 150 (normal) down to 100 and back up to 150-170 with in 3 seconds, sometimes it bounces higher and sets off my high temp alarm. Already replaced Sea water pump and impeller, thermostat, risers. Now I'm thinking sensor is NG?? Any suggestions?

Sounds like the wire for the temp sender is loose or in back of gauge? Also check all grounds.

Bad sender would be an open or short. Meaning full gauge or 0, would not bounce around like that.

 

[hottoddie]

I agree with SKybolt. Bad connection somewhere remote possibility of bad sensor. Oil pressure sensor on my starboard engine just failed and gauge went full negative. $18 fix.

 

[Stee6043]

You mentioned replacing some parts but did you also clean out your strainers?

 

[Brite Idea]

We chased this same problem on my friends boat and it turned out to be the circulator pump(water pump in the front of the engine) The temp gauge would be solid at low speed but a little throttle and it would bounce up and down. We took it apart and the shaft had snapped clean in two!

 

[SloBurn]

I don't have strainers, and just rebuilt sea water pump. Replaced sensor and now reads 180 at idle. That's not a problem though. I think I'm gonna tear pump apart again.