Flushing an outboard

J

JayCbee

Well-Known Member
Joined
18 Jun 2020
Messages
79
Visit site
Hi all. Just some advice. Have a 50bhp 2 stroke mariner on my microplus and wondered what frequency you would recommend flushing with fresh water. We go out in it once a week. Was a reconditioned serviced purchase end of June. I have only recently noticed people flushing out there albeit more powerful 4 strokes. Trying to read up on this to avoid issues.
 
Salt water. Out of Conwy Marina. Every time? I actually need to understand what I need to do to flush it. YouTube here I come !
 
Ok rookie question about flushing. Assume lots of different size flush muffs. So I just look at my intake and choose best for a good fit? Possible stupid question.... When the fresh water hose is running am I ok to turn the engine on ‘out of the water’ otherwise the muffs will be under water I imagine. As fresh water running ok to set the ending running in neutral in the lifted position? Run for 5 mins. Engine off. Water off. Then muffs off and done?
 
Leave the engine in the down position, attach flushing muffs that cover both inlet ports on the leg. Run the tap and check that water is flowing to the muffs. Water will squirt out at the muffs but when you start the engine the impeller has water to suck through. Water should flow from the tell tale and hub of the prop fairly soon after starting. 5 or so minutes should be enough. Then wash the whole engine with a fresh water spray. Let water drain and then lift engine if you need to.. plenty of vids online...
 
Thank you. Understand now about the flushing. Last thing. Not seeing anything about the fresh water spray online. Is that just a mist spray bottle of fresh water and just use on the body of the outboard?
 
As I recall, when flushing the water doesn’t go through the water pump, so don’t run the engine. Also, some outboards have a built in hose attachment so you don’t always need a muff.
 
The muffs re create the same effect as if the leg is immersed in water. It's essential to run the engine to circulate the water... Older 2 strokes rarly have flushing ports either. If you can obtain the original user manual it may mention flushing although engines rotting after 5 years in seawater was good for sales....
 
Bouba said:
As I recall, when flushing the water doesn’t go through the water pump, so don’t run the engine. Also, some outboards have a built in hose attachment so you don’t always need a muff.
Click to expand...
The muffs just replace the surrounding sea water, so yes the water goes through the water pump and yes the engine needs to be running. There isn't some special route up the leg via the back stairs.
 
Catalina36 said:
The muffs just replace the surrounding sea water, so yes the water goes through the water pump and yes the engine needs to be running. There isn't some special route up the leg via the back stairs.
Click to expand...
Ok, I got a little mixed up, I meant that when using a flush port don’t run the engine. My bad
 
JayCbee said:
Ok rookie question about flushing. Assume lots of different size flush muffs. So I just look at my intake and choose best for a good fit? Possible stupid question.... When the fresh water hose is running am I ok to turn the engine on ‘out of the water’ otherwise the muffs will be under water I imagine. As fresh water running ok to set the ending running in neutral in the lifted position? Run for 5 mins. Engine off. Water off. Then muffs off and done?
Click to expand...
You can’t flush it on muffs in the Marina/water
I’m there today and tomorrow
Shore based in the afternoon both days
I’ll show you what to do
 
I've had many outboards from 50 to 200hp ranging from 6 to 25 yrs old.
My boats live on a mooring. No engine has ever been flushed and I've never had a problem related to salt build up.
There are hundreds of outboard powered boats afloat across the road from me and I've never yet come across anyone that has had a problem.
Disimilar metals causing a blockage is a problem though and I can't see that flushing would help.
I've just had to dismantle a 2002 4t 50hp mercury due to rubber bush being crushed and blocking water supply to powerhead caused by disimilar metals (copper, aluminium and stainless steel) . The waterways themselves were absolutely immaculate. That did surprise me..
I'm not saying outboards don't need flushing but they are pretty hardy beasts that can survive years of neglect as long as they are being used.
Running hot can certainly cause crystalisation of sea water internally leading to deposits and therefore more overheating.
If the boat lives out of the water and by a tap then why not flush it every time ?
 
An owner of an outboard motor repair shop once told me that if you leave your boat in the water, keep the leg lowered and in the water. He said it makes a real mess on the outside with barnacles etc but that could be cleaned off. Those who keep the engine raised get air in the system and their outboards rot from the inside out
 
That's interesting Bouba. Would like to know if there is any truth in that.?
All I can say is there is no way I would ever leave an outboard down. It really does make a mess of the lower end. All that paint bare aluminium and stainless steel. ?
 
Rappey said:
That's interesting Bouba. Would like to know if there is any truth in that.?
All I can say is there is no way I would ever leave an outboard down. It really does make a mess of the lower end. All that paint bare aluminium and stainless steel. ?
Click to expand...
I also wondered but I followed his advice (when there were no facilities to flush), I figured his workshop is stripping down outboards all day every day. But generally speaking i have been religious in flushing the engine, for my dingy engine i always ran it in a barrel of fresh water.
 
My dingy engine also gets flushed when I get home as it's a tohatsu 3.5 2t and come across a fair few people that have had blockages from salt.
Also heard larger outboards have much larger waterways so less likely to block.
 
When you see what looks like salt getting rinsed out of the engine there is a good chance it’s aluminum oxide
 
You must log in or register to reply here.

Share this page

Top