Running Temperature

[Mike]

I run merc 454's and I was out for a ride this evening and noticed my port engine running at +/-180 degrees at 3000 rpms. Normally they run at +/- 160. A few minutes after slowing down and running at 1200 rpms the temp went back down to +/- 160. The impellor was replaced this past winter, I have good water flow, so i was thinking it might be the thermostat. Any suggestions on what to look at?

 

[37 Dancer]

Do you have I/O's or Inboards ??

Fresh water cooled or raw ??


Inboards......I'd start with the sea strainers.....then work my way upstream to the coolers...etc.

 

[Mike]

Inboards, fresh water cooled. I'll be doing that today!

 

[osd9]

When you replaced the impellers, did they come out "whole"? The reason I ask, is because if there were pieces missing from the vanes, then those pieces may be blocking some water flow.

 

[Mike]

I "believe" I got all the pieces, i didn't notice any smaller pieces and i was able to piece back the broken impellor. Last weekend on my run at the beginning of the weekend the temp was a little above normal 170, on the way home it was fine and last night hot, 180.

That's why I thought the thermostat might be sticking. I am not sure when the last time those were repleaced, so for $20 I was going to replace them.

Water flow on both engines looks to be good and about the same.