Proper flushing question

[AQUADJ]

I was misinformed about the proper way to flush my 1998 Yamaha 250 hp EFI motor. When I pulled my boat for the season I used the built-in hose connection and ran at idle for about 5 minutes. The water pump has about 150 hours on it. Can I assume I've done damage to the impeller or other parts?

 

[JUSTINTIME]

Re: Proper flushing question

nope u are fine
i say better to run it because this way if anything gets down there it moves out of the way
all that hose is a back flush

 

[Ray Neudecker]

Re: Proper flushing question

The back flush was not intended to use with the motor running, It's purpose is to flush the motor out when it can't be run on muffs to do so. You should not run it on this hose. There is a strong possiblity, you should replace the pump. At that age, it is due anyway.

 

[AQUADJ]

Re: Proper flushing question

Thanks Ray for clafifying that for me. I planned to change the lower unit oil this weekend, will I have to do it again when I drop the lower unit to change the water pump? I'm going to attempt the pump change myself and have never done it.

 

[JUSTINTIME]

Re: Proper flushing question

ray

i know it was not intended for begin not run
i look at my 200 HPDI over the weekend. it just tee's into the water cooling
it is OK to run
i have heard some guys who did not run and the salt got built up under where the impeller picks up water on the metal plate because it was back flushed

 

[Ray Neudecker]

Re: Proper flushing question

There will be no need to change it again, just because you changed the pump or impellor.
I have always considered that back flush sytem a gimmick except if used as intended it is better than doing nothing.
I have seen the salt build up under the plate apparently caused by things other than not running while back flushing since the back flushing hose wasn't on that model.
Once again, I reccomend using the muffs while running on a hose, not the back flush attachment.

 

[Capt Ken]

Re: Proper flushing question

The Yamaha flush attachment located on the side of the engine is attached to the water tube coming up from the water pump to the engine. The reason they say not to run the engine while using this hose is the posibility of not getting enough cooling water to the engine. You will not damage your impeller if you run the engine since it does provide plenty of water to keep the impeller cool. The catch 22 with not running your engine while flushing is the problem of not heating up enough to open the thermostats and completely circulating thru the block.

 

[Ray Neudecker]

Re: Proper flushing question

The reccomendation for the water pump change was primarily because of the age of the unit. If you are going to run the engine to flush it is no harder to hook up muffs and do it properly.

 

[AQUADJ]

Re: Proper flushing question

Thanks everyone for the help.

 

[yamamarinetech40]

Re: Proper flushing question

Just to get my two cents in....why in the world would Yamaha tell us NOT to use the 'flush' attachment to run engine on their own engine if they could say, 'sure run it'? You should never run your engine on the flush attachment....sometimes on big four strokes we use BOTH muffs and flush to run, since the big 4strokes tend to run so hot on muffs....but always have muffs on...

 

[gearyg]

Re: Proper flushing question

Here is my opinion, I will run mine on the flush attachment for only a short time, one or two minutes at the most just to kick over and idle before a trip if it has been sitting for a while. The only danger is overheating, and for a short time, it will not over heat...no chance at idle. If you want to flush while running for an extended period of time, use muffs because it will overheat using the flush attachment. Infact, be sure that the water is on FULL as I did it one time trying to save water and my overheating buzzer went off in about 5min...no damage done though, I just shut it down. FYI, I did notice that the water flow was very slow, the water needs to come shooting out pertty fast inorder for it to cool properly....