Proper motor flushing procedure

Riverrat5065

2003 Yamaha 115 hp 4 stroke motor on my 2006 Hurricane Deckboat After I connect the hose directly to the motor, not using muffs, will gravity flush the salt water adequately or do I need to run the motor also? New to mechanics of boating

nquirk

In order to properly flush you need the engine running (in neutral and never load the engine).  Inside, attached to the drive shaft to the lower unit is the rubber impeller that will  help circulate the water better than just a gravity flush.  Run it for a few minutes and you're good.  Just remember to run the water before starting as a dry start of even a few seconds can burn up the impeller.

Riverrat5065

Thanks so much! New water pump and new impeller installed. I won't make that mistake again.

Giuseppe1

I have a Yamaha 2010 150hp 4 stroke and I had the same question - I found the following Yamaha site explains:

 "Do not start the outboard out of the water. Fatal damage to the powerhead, water pump, and other internal components can occur; the water flow from the garden hose via the freshwater flush fitting won’t properly cool a running outboard." See: http://www.yamahaoutboards.com/yamaha-advantage/news/fishing-tips/boaters-log-volume-1-no-5

You can start it out of water after the fresh water is attached and turned on using the "earmuffs" or a "flush bag"  -- check out yamaha's video to do this - https://www.youtube.com/watch?v=ZJaTjMOEKP0

Pseudomind

2011 Yamaha 115 hp 4 stroke motor on my 2011 Hurricane Sun Deck 187 OB boat.

The Yamaha has two flushing procedures, one is without the engine running using the hose connector I have, they state for best results to tilt motor completely out of the water run for around 15 minutes using the hose connection and to ABSOLUTELY DO NOT RUN the motor when using the hose connection.

Then on the next page they go into flushing using the muffs and running the motor at fast idle for ten or 15 minutes.

They make no mention if both methods need to be performed.

I believe it is an either or procedure, if ones motor has the factory hose connection, use that method.

If one does not have a hose connection then use the muffs. 

What is correct?