Yamaha - Top flush and bottom flush?

[Gobuchul]

If you use the top flush attachment on a Yamaha OB, do you need to use muffs on the bottom as well?

Surely it's a common cooling water system and if your telltale is good then there is no problem?

[twigg]

Top flush is designed to be used without the engine not running so water is not flowing through the upper waterways so best to flush with muffs and engine running

[Fenlander]

Must admit I use the flush adaptor point on my Suzuki just for interim flushing... but at the end of a holiday or before putting away for the winter I always flush running in a container. I like to think with warmed coolant and everything running it does a better job.

[wellhouse]

Originally Posted by twigg

Top flush is designed to be used without the engine not running so water is not flowing through the upper waterways so best to flush with muffs and engine running

is that right? i thought the top flush flushed everything without the engine running?

[jonp]

If you have a Yamaha outboard service book it explains the upper flush mount doesn't flush the entire powerhead, muffs or a silly bucket is needed to do a full flush. When using the muffs or bucket with the engine running at a certain point once warm the thermostat opens allowing water to flush the parts the upper flush doesn't. Also all the Yamaha mechanics I've ever used state not to over rev and engine while muffs are on.

I use a product called saltaway with a special dispenser to help remove all the salt but if your engine is used almost daily it's harder for salt to build up.

Yamaha have videos on YouTube explains this.

[wellhouse]

Originally Posted by jonp

If you have a Yamaha outboard service book it explains the upper flush mount doesn't flush the entire powerhead, muffs or a silly bucket is needed to do a full flush. When using the muffs or bucket with the engine running at a certain point once warm the thermostat opens allowing water to flush the parts the upper flush doesn't. Also all the Yamaha mechanics I've ever used state not to over rev and engine while muffs are on.

I use a product called saltaway with a special dispenser to help remove all the salt but if your engine is used almost daily it's harder for salt to build up.

Yamaha have videos on YouTube explains this.

cheers, i've been religiously flushing after every use on the top flush, just as well i'm paranoid and use the muffs as well!

[jonp]

Originally Posted by wellhouse

cheers, i've been religiously flushing after every use on the top flush, just as well i'm paranoid and use the muffs as well!

Last time I was up in North Queensland I hopped on a crocodile tour boat, that had twin Yamaha f70 ( same as my outboard). I asked the operator his thoughts on the engines, both of which were at 7200hrs. Reply was they need very little maintance and never get flushed but they are run all day every day, at 10000hrs they get demoted down to one of the companies spare boats. Water conditions up there are silty saltwater.

On the flip side my Yam mechanic has seen outboards corroded from the inside out in less than 250 hrs. He mainly services comercial industry outboards which he says are able to do the big hours simply because of the regular use unlike recreational users who often leave outboards unflused for long periods allowing the salt to build up inside.