Impeller replacement

[Bill L]

Hi! Bought my first boat a month ago, already had to replace the impellers. After replacing them, my starboard engine’s RPM keep dropping From 2500 down to 1000, in order for me to bring the RPM’s back up I had to play with the throttle. Did I do something wrong? My belt is a little looser than it was. My fingers are crossed that tightening the halt will help. Any input? Suggestions?

[mjk1040]

Changing the impellers shouldn't effect engine rpms. Did you step on ur throttle cable?

[Bill L]

No, I was laying on my stomach on the floor for the most part.

[Bill L]

It was weird. Ran great idling at the dock. Ran great at 2000 rom’s at the dock. Was losing power when I took it out to the bay when attempting to get on plane

[Bill L]

My oil pressure was also higher than it was before replacing the impeller. Correlation?

[mjk1040]

Did all of the old impellers parts come out, are you running hotter than you should?

[Bill L]

The port engine temp is too low, changing the thermostat tonight (port engine overheated on the water-came back to dock on 1 engine). The starboard engine’s temp ran steady at 150.

[km1125]

Just to be clear... the port engine is the one that has a "too low" temp and the one that overheated, but the stbd engine is the one that keeps dropping RPMs??

If the engine temperature is much cooler now than it was before the impeller was changed, that could account for a higher oil pressure, as the oil also would be cooler (thicker). Which engine are you referring to? If it was the port engine that was overheating then the oil pressure would be expected to be lower than after you changed the impeller and got the temps back to normal. However, if the stbd engine had a normal temp before and after the impeller change that doesn't make sense if it's oil pressure changed.

On any "new to me" engine, it ALWAYS a good idea to replace impellers soon so you know FOR SURE what condition they are in. Applies to any water-cooled engine - outboards, inboards and sterndrives.

[Bill L]

Sorry, I’m all over the place. The port engine’s oil pressure is/ was good before the impeller crapped out on me. I replaced the impeller, now the temp on port engine is too cool, still has the same good oil pressure. I changed the starboard impeller since I changed the port side. After changing the starboard impeller, my oil pressure increased, and the motor struggled when I got to about 2000 rpm’s. To be honest, the issue with the rpm’s could be something entirely different all together. I just found it odd that this problem happened after the impeller switch out.

[km1125]

I'd be checking that main harness that connects to the engine. You might have bumped it and now you have a poor connection there, which would explain an oil pressure gauge reading higher than it should and a faulty connection to the ignition which would cause poor performance. Check all the connections, but that one is common to both issues.