Normal temperature on a 454 mercruiser

[gcreas1]

Have a new engine in my B31, cooling system plumbed with FWC cooled manifolds and raw water cooled risers. What should be the expected normal operating temperature?

At idle after warm up the meter is sitting at a little over 220 degrees.

My old raw water cooled engine would run around 160 degrees, pretty much all the time.

Thanks

[John F.]

My 454s had 160 degree thermostats, so she ran right around 160. It seems to me that you're way high, and something is wrong. Make sure you're pumping plenty of exhaust water. If you are, get a laser heat gun to verify temps. The RW/FW systems is like following a hose--start at your pickups and check your flow.

[gcreas1]

Thanks, since the meter is bouncing all the way up as soon as it starts I'm thinking maybe something is wired incorrectly on the meter side. There appears to be plenty of raw water being pumped through and the exhaust feels cool to the touch at the risers. Pulled the thermostat out just to make sure it wasn't opening. No difference. Going back with an external meter to see what it is reading.

[Rawleigh]

Get an IR thermometer. Very useful for diagnostics.

[Stephan]

Get an IR thermometer. Very useful for diagnostics.

+1
I have Crusader 454s and they run at 160. I check the bronze plug in the top of the thermostat with the IR to double check the gauge and then check the manifolds. On longer runs we have logged the IR temps for the manifolds (old style) front to back, the elbows and the transmission. I don't have that data handy right now but will be pleased to dig it out if it is of interest to you.
Don't get too concerned if the IR gives you varying readings. Try and be exact where you test I have noticed variations of an inch or so can yield significant differences in temp with the IR.
Good luck-
Stephan

[Keith Poe]

try checking the ground on the gage

[Michael]

Wrong sender, ie could be one for dual stations and you may only have one gauge. Or could be wrong sender for the gauge being used Faulty gauge?
I agree with others, confirm actual temp with IR heat gun

[gcreas1]

Much thanks for all the info, will check with an IR temp meter, but checking ground on gauge might be a good place to start.