impeller pulsation

[bryanredfish]

This forum is a God-send! My new 90 h.p. Mercury motor (Saltwater series) had a very brief (2 minutes at the most) period of pulsating from the water flow at idle only. Things seemed fine after I opened it up for awhile, and forgot about it for the rest of the day. All was well for the remainder of the outing. Should I worry about this? As a new boat owner, I'm sensitive to every strange noise (will I ever relax with this thing!?). Thanks much.

 

[Spidybot]

Re: impeller pulsation

I wouldn't worry too much. When the boat is out of the water your cooling system drains itself. Once the leg is submerged water gets in. At this point some air might get trapped in the cooling circuit so when at first you run, the tell tale seems unstable until the water replaces the air. Also, pressure regulator/thermostat are interferring while not yet on working temperature and this affects the tell tale as well.<br />The important thing is to make sure that your impeller (situated below water level in the leg) has ample water supply whenever the motor is started (either by hose when on land or during normal use).<br /><br />If you suspect any malfunction on new equipment you should inform your vendor (in writing if you want to prevent future discussions and/or keep a log of your gear) to maintain your warranty.

 

[bryanredfish]

Re: impeller pulsation

Thanks much for the reply. I will certainly watch carefully for any other "pulsation" events. Incidently, the motor had been run for about 15 minutes (in the water) when it occurred. Don't know if that makes much difference. Could it have been a temporary obstruction? Since I'm in salt/brackish water, I flush religiously.