Installing a flush valve on Honda 225

Hi all, I have twin 2003 Honda BF225's on a Wellcraft Coastal 290 for last few years. First time posting, but I have definitely read up on all the issues and how to's on this site. O2 sensors, t-stats, fault codes etc. Been very helpful. I have the manual and have looked at exploded diagram on mount case in regard to the flush valve. Both engines did not have them installed or were removed at some point prior to my owning them. Ideas about going about installing new one's? Boat is in water now and would do this later this fall.

WHOA??? Are you saying those engines have not been flushed since you bought it? Are you running in freshwater (maybe not a problem) or saltwater (a serious problem.)

See: https://www.boats.net/catalog/honda/outboard-by-hp-serial-range/225hp/bf225a3-la-2003/mount-case

Parts 5, 14, 6, 8, 36, 39, and 4. These are all easily accessible from the starboard side of the engine by removing the starboard upper cowling. What parts are still there?
Part 4 is where your garden hose hooks up and it should have a plastic female fitting for screwing in the garden hose. Hose 36 weaves behind the forward section of the upper cowling and terminates in the port water jacket (I think - memory is a bit foggy on the termination point.)

Also see: View attachment Flush Valve.pdf

I flush it from the lower unit with muffs, but while at the dock it is challenging. Pretty sure previous owner ran these pretty good and did bare minimum on the maintenance schedule. I have read a lot of your input Chawk_man, always helpful. Wasn't sure how difficult it was to install. Some guys I know use salt away when flushing to rid the buildup. I am sure I have plenty of it inside. They have about 930 hours on each. Thanks again for all your insight here

Were the engines run in freshwater or saltwater?

A while back I did a few simple experiments with the flushing system. My conclusion is that it didn't do all it should. Flushing water took a long time to reach the thermostats, and with no pressure. It just oozed up there after about 15 minutes. I don't think a good job flushing the exhaust manifolds, either.

Running the 225 on muffs is probably better in the long run, but you need a lot of water pressure and some really good muffs that cover the intakes very well. My 225 will sound an overheat alarm after about 5 minutes on muffs. Others have reported no overheating.

when i pull the boat for the season next month I will be able to pull the cowling off and see whats where. Thanks for the confirmation on the Boat.net parts, I plan on ordering and doing the install. I was told to flush while motor is hot/warm as the thermostats are still open and allows fresh water to flow through them. Boat is in salt water but docked in brackish. I changed the t stats on one engine this season due to alarm. Thought it was O2 sensor, until I pulled the t stats and saw how corroded they get. I ordered two more to do the other engine. Learning process like anything else though. First time owning twins and first Honda's. I have read many of your posts and are always helpful and knowledgeable. Thanks again Chawk

If you are going to do your own maintenance and repair, spend $126 on the Helm Shop Manual. Make sure you get the one for your engines.

Also, here is a link to an older shop manual, It's in PDF format, so you can save it to your computer. It's about 22 MBytes. On the opening page, scroll down the left side to the bottom and you will see a search box. That is very useful for finding stuff in the manual.

http://planbmarine.com/wp-content/u...ice-workshop-and-repair-BF175A-BF200A-BF2.pdf

As soon as cool water hits the t-stats they close. Plus, flushing water barely gets to them with normal water pressure. Just plan to change them out every year or two.

given how small those t stats are I am changing them and the gaskets pretty regularly now. I have the pdf now and the boats.net is nice with exploded diagrams. I will look for a helm shop manual too
thanks again