Muffs and flushing outboards, freshwater and sea

[Croolis]

Do you folks use the muff things? Are you OK with them? Do you flush every time after use in freshwater?

It's a bit of a PITA for me at the moment because I don't have a water tap in the back garden. Last time I ran the engine in a kitchen bin full of water, not ideal really. All things being equal I'd rather use muffs and see about getting a hose adapter for the kitchen sink.

Any thoughts folks?

[Matt]

Depends on the motor, but universally, yes, I always flush my engines:

• Mariner 2hp : I sometimes take the prop off so I don't need such a big container.
• Johnson 5hp : Has gears, so I run it in neutral
• Inboard 600hp (but stored ashore, not in the water): Classic flush muffs, although I have just bought one of these:
• https://www.hardin-marine.com/p-1374...connector.aspx
• It's a good bit of kit, although I now know it's actually one of these just rebranded : https://www.amazon.com/Aquor-Deckwas.../dp/B08NC3XVS5

So on the 2 (minus prop) & the 5, I use something like this, with a little wooden from to mount the engine to - it's just big enough to fit them in and ensure that water intakes are covered:
https://www.ebay.co.uk/itm/134647709572

Happy to take a pic & share the setup if useful.

[Trello]

I've never had much success with hose adaptors on kitchen taps - they're liable to suddenly pop off, or at least leak. And if that happens, you're going to get a reduced or absent flow to your engine whilst it's running.
So if you do go down that route, I'd make sure you've got a really, really reliable connection in the kitchen first.

[Croolis]

Thank 'ee folks. That's a good point about the hose popping off the tap. Maybe I'll still do it but maybe do the bucket thing instead of muffs.

[Steve509926]

Hi Croolis, I flush every time the outboard goes back into the garage, whether I've been in salt or fresh. I use muffs even though the Merc does have a flushing port.
Providing your kitchen sink is on an outside wall it really isn't a difficult diy job to fit an outside tap.

[Tommy c]

Originally Posted by Croolis

Do you folks use the muff things? Are you OK with them? Do you flush every time after use in freshwater?

It's a bit of a PITA for me at the moment because I don't have a water tap in the back garden. Last time I ran the engine in a kitchen bin full of water, not ideal really. All things being equal I'd rather use muffs and see about getting a hose adapter for the kitchen sink.

Any thoughts folks?

Will muffs fit onto a 2.5?

[A1an]

i personally wouldnt bother after use in fresh water

[Croolis]

Originally Posted by Steve509926

Hi Croolis, I flush every time the outboard goes back into the garage, whether I've been in salt or fresh. I use muffs even though the Merc does have a flushing port.
Providing your kitchen sink is on an outside wall it really isn't a difficult diy job to fit an outside tap.

Yeaheyeknow, and in fact there's a chap at work who has a tap kit and who has offered to come round and do it just for giggles, but I'm renting, and I could do it without asking landlady. Or ask her, but she hasn't put my rent up in 4 years and I hardly ever speak to her, so that's a cage I ain't rattling .

So I might just keep it simple. I got a tap adaptor coming, 6 quid, so I'll see how I get on.

[Croolis]

Originally Posted by Tommy c

Will muffs fit onto a 2.5?

Dunno, not actually looked into buying any yet. Will have a look and post up.

[Trello]

Originally Posted by Steve509926

Providing your kitchen sink is on an outside wall it really isn't a difficult diy job to fit an outside tap.

Yes, I agree - the best solution is to have an outside tap with a screw thread.
If you aren't confident about making plumbing connections (which are actually very straightforward to do, but are usually in really awkward places), then there are kits such as this one which basically just cut a (sealed) hole into your pipework using a self-tapping screw type arrangement. I've never used one, but they look like a simple solution.

https://www.screwfix.com/p/outside-t...m-x-1-2-/33139

[Trello]

Oops, #8 and #9 were posted as I was writing.

[69cmw]

Originally Posted by A1an

i personally wouldnt bother after use in fresh water

Aye, I don’t see the point either 🤷🏼

[Fenlander]

River water of course isn't sparkling like tap water and can leave a scum on the outside of the OB so I'd not criticise anyone that does but I rarely flush after river use.

Re how to flush it's just a personal thing but I do prefer the outboard to be running and pumping its water round with a submerged exhaust in a bucket or some sort.

I picked up a cheap bucket (to match my wheels) in Homebase a few years back and it's proved ideal. Deep enough to work with all OBs so far but not so big it takes ages to fill.

[Croolis]

Originally Posted by Fenlander

River water of course isn't sparkling like tap water and can leave a scum on the outside of the OB so I'd not criticise anyone that does but I rarely flush after river use.

I've only ever done it once, usage been all in the Trent and Ullswater. But silt is a thing, and having watched vids of people splitting an engine and removing salt and sand build up from sea water, I fancy that NEVER doing it isn't a good idea, probably, but I dunno.

I go for a lunchtime walk every day past Beeston marina - I'm going to stick my head in to that mechanic there and ask him about it.

[Peter_C]

Originally Posted by A1an

i personally wouldnt bother after use in fresh water

Originally Posted by 69cmw

Aye, I don’t see the point either 🤷🏼

Unless you just want your neighbors to hear how awesome your outboard sounds Or just to hear it yourself

I flush every time after salt water, but with the Honda's I don't need to start the engine, just hook to the flush port and run some water thru them. Easy and quiet.

Originally Posted by Trello

Yes, I agree - the best solution is to have an outside tap with a screw thread.
If you aren't confident about making plumbing connections (which are actually very straightforward to do, but are usually in really awkward places), then there are kits such as this one which basically just cut a (sealed) hole into your pipework using a self-tapping screw type arrangement. I've never used one, but they look like a simple solution.

https://www.screwfix.com/p/outside-t...m-x-1-2-/33139

NO, NO, and NO! Those connections put a hole into a pipe that is sealed by an o-ring. They are prone to failure. Better off using a tee connector screwed in where the hoses attach. At least then it uses a fully captured seal.

[Steve509926]

Originally Posted by Peter_C

Unless you just want your neighbors to hear how awesome your outboard sounds Or just to hear it yourself

I honestly can't see why you wouldn't want to flush out your OB before cleaning it and putting it away for what could be a couple of months whether it's been in salt or fresh water. It only takes minutes and as far as I'm concerned it's a good habit to get into.

Originally Posted by Peter_C

Honda's I don't need to start the engine, just hook to the flush port and run some water thru them. Easy and quiet.

Now that's what I use to do with my Mercury EFI until I was told by the guy who services OB's that the thermostat doesn't open up unless the engine is running so you are not doing a full flush. He could have been talking a lot of bollocks but it sounds completely plausible to me.

Originally Posted by Peter_C

NO, NO, and NO! Those connections put a hole into a pipe that is sealed by an o-ring. They are prone to failure. Better off using a tee connector screwed in where the hoses attach. At least then it uses a fully captured seal.

I'd agree but for different reasons. Twice over the past couple of years I have had to replace tap tailpipes which have become blocked by the small disc of copper that is cut out using the "outside tap connector".

[Trello]

Originally Posted by Steve509926

I was told by the guy who services OB's that the thermostat doesn't open up unless the engine is running so you are not doing a full flush.

I don't quite see how that would work. If the thermostat still works in the way I was taught in schoolboy physics, it'll be a bimetallic strip which works as a fairly passive component, not requiring any input from the engine.
Unless perhaps the engine opens up an entry for water to run into the thermostat...

I queried elsewhere the logic of the actual passageways of the water-cooling circuit but have still not been enlightened - #11 of the following:

https://www.rib.net/forum/f36/help-p...ked-89678.html

[Nasher]

The Thermostat will open of it's own accord with no other input from the engine, apart of course the heat generated by the engine.

So, if the engine isn't running AND getting itself up to a temperature where the Thermostat opens, any flushing water used either in a bucket or a hose connection downstream of the thermostat won't reach the most important bits, ie the cylinders and heads.

I can't say that ALL manufacturers don't cover this with hose connectors, but I know for sure that connecting to the hose port on my old 200EFI Suzuki didn't get flushing water to the heads etc until the engine was at a temperature where the Thermostat opened.

[Matt]

Are you sure? By the nature of the way "open" cooling systems on outboards work, you need some flow up through the block and heads at all times, a. to warm up properly so the stats knows when to open and b. to vent air etc out when you first start up after putting it in the water and avoid hotspots.

A classic screw up on the old merc V6 days was to remove the stat on the heads entirely - which would cause the motor to blow up! You needed some water pressure in the heads to avoid steam pockets & hotspots!

In older days this was by a small pisser hole in the stat, unsure about most recent motors, but you're still going to need some flow through the block and heads. And even on a fully closed (inboard) system these days, you still usually have full flow through the block and heads.

Regardless, I'd still always wash and flush my motors after salt water use.

[Nasher]

Hey Matt

Perhaps there is a limited flow with the stat closed, I'm going off what I was told years ago.

But, the stat is there to open up flow of coolant once the engine is up to temperature, so there must be some parts of the full system that do not get flow, or perhaps proper flow, until it's open. There is no point in it being there otherwise.
So the only way to ensure a full flush is to make sure the Stat is open by getting the engine up to temperature.

As an aside regarding your comment about removing the stat completely.
We used to remove them in the old Chrysler engines my Father used to favour because they used to stick shut too often and the engine would overheat.
But we replaced them with large Stainless Washer that maintained the pressure and flow at somewhere nearer the factory amount than an open housing.