Temp gauge fuctuating 500ho carbureted

[Sikboats]

I have a late 90's 500 hp I did a water impeller on , cleared all hoses and oil cooler and have great flow out of exhaust. Problem is the temp gauge keeps going from 130 to 180. Replaced thermostat and insured that grounding gasket was at base, replaced temp sensor and used my heat gun an the hottest temp reading I could get was 150 at the oil pan everything else is below 100. Grounded temp gauge and it peg's.Replaced 1" dump hose on port header because it was collapsed inside. About the only thin that hasnt been replaced is the water circulating pump , any ideas?

 

[jigngrub]

Re: Temp gauge fuctuating 500ho carbureted

Take it to a professional technician, that's what they get paid for!

... you probably could've paid for the shop fix with all the parts and labor that didn't work!



... btw, have you replaced the temp gauge?

 

[Sikboats]

Re: Temp gauge fuctuating 500ho carbureted

Umm I am and it was a service that is why the Impeller was replaced, the thermo housing was leaking so while in the replaced it. Ohms on water temp sensor were wildly fluctuating so I thought that may have been it. Didnt you read that I grounded the gauge and it pegged? Besides a bad gauge wouldent search like that. Amazing

 

[LippCJ7]

Re: Temp gauge fuctuating 500ho carbureted

Have you checked the resistance between the motor and the negative battery post?

 

[Fireman431]

Re: Temp gauge fuctuating 500ho carbureted

What thermostat is in it? If you have a 160?-170?, your gauge might be just a little off, but otherwise reading correctly.