Temp Guage Fluctuation

[kopy kat]

My '99 SeaRay temp guage for the 350 EFI / Alpha 1 system is driving me nuts! It will fluctuate from 170 to <130 degrees and back as I run across the lake. The temp stays higher at 4200+ RPM than at 3400 RPM. The impeller was replaced by an authorized dealer a few months ago. I replaced the original 160 degree thermostat with an available Mercury 140 unit, but the temp still swings back and forth. The engine runs fine. Any ideas, or do I have to just learn to live with the guage moving around so much? <br /> <br />Thanks, kopy kat.

 

[crazy charlie]

Re: Temp Guage Fluctuation

Try replacing the gauge and sender first,then start trouble shooting the cooling system.Fresh or salt water cooled????? Charlie

 

[Bondo]

Re: Temp Guage Fluctuation

That's the T-stat opening,+ Closing.....<br /><br />You Don't have a Problem......

 

[McKenzie]

Re: Temp Guage Fluctuation

How fast does the gauge fluctuate? Is it fast like the gauge is loosing power or signal? I would rig a multimeter into the power terminal on the gauge and drive around. When the gauge drops down, has it lost power? If not, rig the multimeter to the signal terminal and put it on the appropriate ohm scale. when the gauge drops, do the ohms show infinity or an extremely high resistance?

 

[fone_man]

Re: Temp Guage Fluctuation

I agree with bondo....<br /><br />We are not running a automobile w/ closed system in which water tempature remains pretty constant in terms of degrees. As your engine stat opens it draws in cool water thus 130* w/140* stat so when running 4200 RPM engine is generating more consistent heat transfer hence higher temps. As long as you do not overheat engine 170* is reasonable for marine engines... if you are watching gauge that much you will truly know when you are oveheating engine. So enjoy your time on the water & enjoy the scenery more & try to lay off gauges. Have Fun!!!!

 

[kopy kat]

Re: Temp Guage Fluctuation

Thanks for the responses--unfortunately----my boat overheated suddenly in the middle of Lake Tahoe--$150 for a 30 minute tow! now in the hands of one of the lake service shops--oh well,, we all know that boats are a luxuary, not an investment, right?