Water Temperature Gauge Rapid Needle Movement

[Chip]

Thanks Dunk for the info on the oil/gas ratio.<br />I have another question regarding the water temperature gauge rapid back and forth needle movement on my 150 hp 1980 Johnson. When at idle, the temperature is about 140 degrees F. - but when running at cruise speed(30 mph) the temperature is about the same as the Bay temp.(60 - 70 degrees F.) and the gauge needle moves rapidly back and forth. I think the cool temperature when running is affecting my fuel consumption and I wonder if the thermostats are working or the pressure valve springs are too weak to maintain a constant temperature.<br />Thanks for any help/thoughts on my problem.<br /><br />Chip

 

[Dunk]

Re: Water Temperature Gauge Rapid Needle Movement

I think I'd be checking the connections on the gauge. There's noway the engine is dropping back to 60-70 degrees under a load. Those popet valves are the old style and from 140 temp your stating it's little low. She should be idling in the 150-160 range them it should drop back to about 135-145 when you up over 2000. It sounds to me like the popets are stuck open. I'd pull them off and clean and check them. Replace the tstats if they look overly corroded. Pay attention and make sure they are not leaking water from the little hole in the center of the housing.

 

[Chip]

Re: Water Temperature Gauge Rapid Needle Movement

Dunk<br />Thanks for the input. I'll try to clean the relief valves.<br /><br />Chip