2008 Yamaha F250 4 stroke flushing procedure

[Finbreaker]

I am trying to figure out the simple answer to proper flushing of my 2008 Yamaha F250 4 stroke outboard motor.. My owner's manual gives instructions on how to use the garden hose attachment to flush the power unit part of the motor, then directs me to page 48 for instructions on flushing the cooling system. However, there are no instructions on page 48 for flushing the cooling system! It is ridiculous how difficult it is to find the proper way to flush your motor. After an extensive online search last night, according to Yamaha, any of the three flushing procedures work equally well (hose attachment, motor muffs with engine running, and flush bag with engine running). But some other sources say you have to do the hose attachment flushing process along with the motor muff and engine running flush to open the thermostat and get the whole cooling system flushed. Again, according to Yamaha, the hose attachment flush will flush all areas of the cooling system whether the motor is hot or cold due to small bypass holes in the thermostat that allow flush water to flow through. To add to the confusion, Yamaha adds a small disclosure that the motor muff flushing process may not work on some motors due to multiple water inlet openings on the lower unit on some motors, but in my owner's manual it only shows that my motor has 2 water inlets- one on either side of the lower unit. The reason I am asking this question is that I tried the dual method of flushing my motor yesterday, starting with the hose attachment and the motor off, then attached the motor muffs and started the engine while the water was running. The water came out of the pilot hole just fine when I did the hose attachment flush procedure, but during the motor muff flushing process, I noticed zero water flow out of the pilot hole. I did not hear any alarms or buzzers but immediately shut down my engine, and hope I didn't cause any damage because upon closer inspection- lo and behold I think I have more than two water inlets on the lower unit! Thanks Yamaha for your crappy owner's manual diagrams! Anyway, I am just trying to see if anyone else out there just uses the simple hose attachment flushing method and can this be the one and only method to flush the entire cooling system? I also want to use my Salt Away attachment during flushing but only see the Salt Away being used in videos with the flush muff procedure not the upper unit hose attachment.

 

[Brent]

I found the owners manual by using Google
see http://www.yamaha-motor.com/assets/serv ... 6_1395.pdf
on page 50

This use the above method with the motor off. Sometimes use muffs with the OB motor running and check the mufsf are firmly attached, has good water flow, and good water stream from tell tale port. A flushing bag or tank with lots of water would be great
Alas, I dont use Salt Away

 

[warthog5]

I've never seen a Yamaha 4 stroke that didn't sound the overheat alarm while trying to run it on muffs.

With the same hose and hooked to the same well water and with the same dual engine setup.... I can run 2 - Suzuki's on the muffs with no problem.

It's a design deal. I've spoken to Yamaha mechanics about this in the past. Yamaha's are better off run in a tank.

But back to your question. Hook the hose to the powerhead port.... Do Not crank motor. Run water for min of 5mins. Reinstall cap on powerhead port. Failure to reinstall that cap..... The motor will suck air and overheat on the water.

 

[Finbreaker]

Yes, even though it just seems like I would get a more thorough flush from the muffs since this is the natural way sea water is drawn into the motor in the first place, I will have to just rely on the hose attachment on the power head and hope this does a sufficient enough fresh water flush. Too many water inlets on the lower unit of my F250 to deal with!

 

[warthog5]

Inducing some Salt Away will help also. Maybe every 4th time.

 

[Marty D]

I am in the same boat as you. How do I flush my motor when I'm at dock. I read the book and don't think it's right. We all know the ears is the right way but at dock that's hard to do. I'm not even going to talk about the 2 nd water intake at lower unit. Let flush the motor using the water hose inlet at the motor. You come to dock hot, leave it running. I hook up the hose to the power head and turn the water on. I raise the motor all the way up and turn the eng off. Now I know the water is going pass the eng block and out the lower unit. Because if you close the motor off when you come to dock and hook up the water hose, as soon as the cold water hits the thermostat, they will close, fast. You will not be cleaning out the Eng. this is the only way I see how it can be done the right way!! I still called Yamaha and spoke to there service tec. He said that is fine and as long as you leave the motor running under 2,000 RPM you will be fine. I ask him why don't they say to do that? People that don't unstand will run the motor higher then 2000 rpm. Also if they ran the motor and raise the motor without running the hose water they will damage motor. All I know is I had a Yamaha for 10 years with 3500 hours and sold it for $5500 and she ran like new. I now have a Suzuki 250 and I'm flushing the same way.

 

[Megabyte]

I flush my OX66 at the dock using the flush port.
Notice the yellow garden hose attached to the port in the first photo, and the flow through the motor in the second photo.

If you have good water pressure dockside, you should get similar results.

I also give the motor a SaltAway treatment about once a month during the season.
The SaltAway canister simply attaches between the garden hose and the flush port.
It's good insurance.