'07 R21-EC engine temperature climbs on increase in RPM

r67boxer

Active member
Joined
Jun 26, 2025
Messages
25
Fluid Motion Model
R-21 EC
Hull Identification Number
FMLT2148A707
Vessel Name
Pacific Wren
While out on a cruise the other day my engine temperature registered, as it always does, just shy of 175 degrees. I was running along at about 2200 RPM. When I increased the engine speed to 3100 RPM I noticed a slow creep up to about 177 degrees. Is this normal or is it time to change the sea water impeller?

Kevin
 
It's not unusual and it's nothing to worry about as long as it doesn't keep going up. Good idea to open it up to wide open throttle every now and make sure the temp holds steady. Raw water impeller is normally a 2 year replacement item.
 
It's not unusual and it's nothing to worry about as long as it doesn't keep going up. Good idea to open it up to wide open throttle every now and make sure the temp holds steady. Raw water impeller is normally a 2 year replacement item.
Thanks. I will keep an eye on it. The R21 is new to me so no history to speak of but there was a spare impeller and O-ring in one of the cupboards.

Kevin
 
If you don't have details on when that impeller was last changed, then it should be replaced, or at least inspected immediately.
I'd say that the same goes for fluids, filters etc on a new to you boat.

Just my $0.02
 
Just an opinion but I would think that a 2 or 3 degree temperature rise with an increase of 900rpms is quite insignificant.
 
If you don't have details on when that impeller was last changed, then it should be replaced, or at least inspected immediately.
I'd say that the same goes for fluids, filters etc on a new to you boat.

Just my $0.02
As I said above I will keep and eye on the temperature but will also pull the cover off the pump to check the impeller. I have gone through the entire boat WRT fluids etc. and have changed the water separator filter, as well as fuel filter. The engine oil had just been changed and transmission oil is up and clean.

Thanks to all for your input.

Kevin
 
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