Mercruiser 470 coolant temp sensor and other questions

[jturbo86]

According to my gauge, the engine is running hot.... after not running for long. Going to replace the thermostat and temp sensor. After some reading, it seems like I need Sierra TS26621 but cannot confirm. I think the boat may have the wrong one installed causing it to read hotter than it actually is.
I have the 4" exchanger and cleaned/checked for blockages and everything seems to be good. Before I go crazy chasing down something thats not a real issue, I'd rather replace the sensor and see if that changes anything.

As far as oil goes, Im planning on running a 50/50 mix of vr1 20-50 and 10-30 since i has a high zinc content and I have a lot on hand. I live on long island so water temps are 65-75.

Thanks,
John

 

[jturbo86]

One more thing, while im at it, im going to replace the oil pressure sensor with a Standard Motor Products PS60 Oil Pressure Sender unless someone recommends something different. Seems like some of the other ones are not stainless and people say they rust.

 

[Bt Doctur]

Is the impeller new? does it happen at idle or at cruise? elbow clogging? leaking head gasket from a overheat?

 

[jturbo86]

Is the impeller new? does it happen at idle or at cruise? elbow clogging? leaking head gasket from a overheat?

Just did the impeller, getting plenty of flow. Its happening while parked with the rabbit ears on... trying to get it sea worthy

Either way im replacing the sensors, they are pretty old and I want to be able to rely on the readings, as much as you can rely on readings coming from a 470

I dont think its a head gasket as compression seems good. Im really leaning towards the sensor since it happens so quickly.

 

[stonyloam]

What is “hot”? It should have a 165 F thermostat, so it should run around there. Does the temperature keep rising, or does it stabilize?