Water pump question

[Reckless]

  Will the stream be the same when running on muffs vs under normal running conditions? I wouldn't think it would be but what do I know?

Thanks!!

[Hotrod]

I recall.  that being No.  based on the fit of the muffs..  the muffs  produce a lot of air I believe.. 

[Reckless]

  I replaced the pump so I paid more attention to it than normal. The stream seems to fluctuate. Being on the muffs I guess it can suck air which would cause that. 

[Hotrod]

I would think..  Could also have something clogged in the discharge. remember this is just a Visual to let you know your pumping..  IF you plug it up. you will still get circulation..  I've pulled a lot of crap out of mine once..

[Salty Dog]

After each use,I flush using muffs . Mine is a 25 Hp Yamaha . The stream isn't as strong as it is in the water,but yes ,it's steady .

[Reckless]

 Does the stream vary with T stats opening and closing? 

[L.T.]

Good Question, I would think No.  I'm just guessing here but, If it is designed to let you know if the water pump is working, I would think that it would be engineered to by-pass the thermostat area and be your basic indicator of pump operation so  you can detect before engine overheating 

[Reckless]

 There is probably nothing wrong but seeing the stream vary bothers me. With the T stats open I would think there would be less volume going out the pee hole. Especially at an idle I would think it would be noticeable. Higher RPM less so. More volume. 

[wb]

There is probably nothing wrong but seeing the stream vary bothers me. With the T stats open I would think there would be less volume going out the pee hole. Especially at an idle I would think it would be noticeable. Higher RPM less so. More volume. 

Not true- the pisser is very low volume compared to the actual pump capacity. 1 vs. 2 inlet muffs, their placement over the intake grates, the spring presure holding the muffs up against the LU all combine to make running on the muffs a poor indicator of cooling flow. Also most hoses have nowhere near the flow capacity of a marine engine water pump. Higher rpms will starve the pump when on the muffs. You can really only judge it properly when the LU is in the water fully trimmed down.

[Andys Delight]

Gotta be honest, I used to flush my 130 hp Johnson after every trip last year when I trailered it.  Never really saw a difference in pee volume on the muffs vs in the water except when I opened up the throttle on the water.  If you are seeing fluctuation on the muffs it likely has to do with water flow coming from the hose, ie air pockets or just pressure differences.  I would use the shortest feasible hose length when running on the muffs to eliminate air pockets and kinks. 

[Reckless]

 Guess the best thing to do is see how it is when in the water. To many things can be causing it on the muffs. Its not rocket science replacing a pump. Unless I am sucking air around the pump housing.

Thanks for all the feedback!! 

[Maritime Matt]

We find with the Yamahas, we remove both screens at the lower unit water pick-up when we run them on the muffs. Without them, there is no obstruction for water. If in doubt, back  down a ramp, leave it tied to the trailer and fire it up.

[Reckless]

  Muffs was causing the fluctuating in the stream. Found a tank big enough to run it in and the stream has good pressure and solid with no fluctuating.

Thanks for everyones input.