Mercury FourStroke freshwater hose coupling?

[Segelplaner]

Hi!
We have a dinghy engine Mercury FourStroke 4hp, new and bought last winter.
The documentation does not match the engine.
There is no plug as described in documentation.

Where is the water hose coupling plug located?



Thanks
Jonas

[thomm225]

What do you mean by coupling plug?

The bolt/plug that you remove to allow you to hookup the hose coupling? That bolt is about in the area of A on your diagram. It's the odd bolt in the group there maybe a little larger if I remember correctly

I haven't flushed mine a lot, maybe 10X in 7 years, but I have flushed it. Also remember the manual says not to start the engine while flushing

I have the Mercury 5 hp 4 stroke extra long shaft as my boat's primary engine.....since 2011

[Segelplaner]

Here is a picture of my engine.
Compare that to the documentation.
Am I missing something?

[thomm225]

Originally Posted by Segelplaner

Here is a picture of my engine.
Compare that to the documentation.
Am I missing something?

Attachment 179682

It's the larger bolt just inside the other bolt in your picture …..right side.

Notice the other three bolts are the same ……..the larger one is the plug. (the fourth bolt isn't pictured but you don't care about that one anyway

[Segelplaner]

Thanks, that was my best guess!
Did not want to test unscrew that bigger bolt and
throw in some water by chance.

[thomm225]

Originally Posted by Segelplaner

Thanks, that was my best guess!
Did not want to test unscrew that bigger bolt and
throw in some water by chance.

That's always my biggest worry since the motor is usually hanging off the boat over the water when I remove that bolt.

When the boat is on the hard I flush the old way with the lower unit in a bucket

[Segelplaner]

Do I need to run the engine sometime before flushing, or can I flush a ”cold” engine?

[thomm225]

Originally Posted by Segelplaner

Do I need to run the engine sometime before flushing, or can I flush a ”cold” engine?

Not sure which is best. I've done it both ways in the past at different times.

My engine usually only gets a saltwater flush …….. I start it at least once a week in season and once or twice a month in Winter if above freezing

[srbaum]

Jonas,
I went a different path and all of my friends have followed suit. I purchased a Yamaha jet ski flush hose on eBay and connected it to a home garden hose cut off valve from Lowes. Removed the flush plug that was discussed in this thread. Installed the removed fastener's gasket on the Yamaha flush hose. applied Tef-Gel to the threads (to prevent it from causing corrosion to the engine block) and screwed it it the hole where the fastener was removed.
Before this, I only flushed the outboard on my trimaran, when I pulled the boat out of the water at the end of the year. I did try to to flush my new outboard that I installed in 2003, but after a while, I got lazy... After performing a major repair to that outboard a few years later, due to corrosion, I started paying attention.
The new flush attachment allows me to easily flush the outboard after use, when I am rinsing off the boat. No more corrosion issues!
You must be diligent when using this simple flush device and ensure that you close the garden hose cut off valve after flushing. If you fail to do this, the water that is sent to the powerhead, via the water pump will drain too fast and your engine WILL overheat and fail.
PS, your outboard is a Tohatsu and rebadged Mercury. The same outboard is also rebadged Evinrude and Nissan...
Steve Baum

[thomm225]

Originally Posted by srbaum

PS, your outboard is a Tohatsu and rebadged Mercury. The same outboard is also rebadged Evinrude and Nissan...
Steve BaumAttachment 179709

Attachment 179710

So my 5 hp Mercury outboard finally got the dreaded carb problem from the ethanol fuel I'm guessing and it wouldn't idle.

So I watched a video on youtube about how to fix it on a Tohatsu. I left work early to do the simple carb removal/cleaning job but when I went to remove the carb it was totally different from the youtube film

I would have had to disassemble half the engine to get the carburetor off. luckily for me I was able to get one of the jets/nozzles off without removing anything and clean it

That fixed the problem.

Point is the engines are different here and there

[srbaum]

Thomm225,
My reply was about the Jonas' 4 stroke flushing concerns. The engine that he has is the same as all Tohatsu (and rebranded Mercury, Nissan and Evinrude) 4, 5 and 6 HP, 4 stroke outboards. Those carbs are very easy to remove and disassemble. The BEST way to clean them (as well as others) is to place all of the parts in a simple ultrasonic cleaner (such as the ones sold by Harbor Freight) with a bit of Simple Green Cleaner.
For parts I shop at boats.net. Good prices, parts schematics and fast shipping.

[Segelplaner]

Found the much better Tohatsu Owners manual and description about flushing that matches the engine I got. https://www.tohatsu.com/int/tech_inf...lish%20web.pdf

But here the manual says that the engine should run?

[thomm225]

Originally Posted by srbaum

Thomm225,
My reply was about the Jonas' 4 stroke flushing concerns. The engine that he has is the same as all Tohatsu (and rebranded Mercury, Nissan and Evinrude) 4, 5 and 6 HP, 4 stroke outboards. Those carbs are very easy to remove and disassemble. The BEST way to clean them (as well as others) is to place all of the parts in a simple ultrasonic cleaner (such as the ones sold by Harbor Freight) with a bit of Simple Green Cleaner.
For parts I shop at boats.net. Good prices, parts schematics and fast shipping.

Yeah, I have the 5 hp 4 stroke Mercury and my point was I fixed the problem without removing the carb and went sailing that same day.

All this after I got off work on weekday afternoon