Double Muff pic

[Lucky_Phill]

here it is

[gavsgonefishing]

I'm just wondering why??

[basserman]

gets better flow throught the water impellor and up into the thermo as you have water getting pushed in from both sides of the motor

[Fishinmishin]

With the title i was all excited to open the post. What a let down ;D.
Cheers, Jay

[Wear_the_fox_hat]

Done the same with my muffs. Works a treat.

[saphire]

How creative you are.

[James_V17L]

I am with you Jay...DOH..!!! ;D ;D

[SCOTTYGC]

BUGGER
got me too

;D ;D ;D

[_Matt_]

Me three

[blaze]

I like the idea
What I cant understand (being the thinking person I am) is that if your hose puts out 25lb pressure and the pickup in the leg is 2 openings on opisite sides of the leg leading into a common chamber, the pressure inside that common chamber will be 25lb wether it be fed from 1 side or 2.
Flow
If you wanted to increase flow, you would need 2 x 1/2 hoses(one to either side of the muffs) running from 1 x 1" outlet, Flow is reduced by friction/restriction, so by having a 1/2" hose split at the muffs it cannot increase flow after it has been resricted.
Now I am not saying it doesnt work but all the theories say it should not make the system any better than a single sided muff
please it tell me why it does work
cheers
blaze

[adrian]

me four
;D
i have to agree blaze

[basserman]

ok can explain one of the ways it works just not sure how good of a job i will do

with the single hose muffs you have all the water presure comeing in for one side and pushing against the other side
this helps break the seal and allows some of the water to escape
where with the twin you have to inlets pumping water in from oppiset sides causeing the water streams to hit each other and stay where it is and this is how it allows what seem to be more water to be pumped and flushing
yes there is no diffrenct in water volume comeing out of the hose but there should be going into the donk

as i said could explain well but i hope it helps

[szopen]

OK my attempt at explanation.

I have absolutely no idea what this thing is or what it does.

If I understand above posts correctly water goes in through two inlets with the black thingy on them and out through the yellow Y joint at the other end.

Why it would let more water through than one with a single intake?

I would say that:

1. There is actually a pressure drop through the pipe from the inlet to the outlet, amount of this pressure drop is related to the pipe size (cross section)and the flow speed. Using two pipes increases the effective cross section and that results in lower pressure drop through the pipes and higher pressure at the Y joint giving a better flow.
(If above is correct even better result could be achieved by simply using pipe of biger diameter)

2. With 2 inlets the pressure of water at the Y joint fluctuates less getting more even flow rate.

[Big_Kev]

Blaze, one of the first rules of hydrophysics is that when you have flow across an orrifice (as being the muff inlet) there will be a reduction in pressure on the opposing downstream side.
This is caused due to the reduction of the surface area between the hose diameter and the plastic hose fitting.
So I guess Proffersor Phil is trying to overcome this by increaing the surface area of the orrifice -
*increasing them 2 fold,
*therebye increasing the flow.

Thus there will be an increase in pressure in the
*"common chamber" #impellor area
due to the greater volume of water.

Do you concur Proffesor Blaze or, it appears professor Szopen does.
Cheers Professor Hard. LOL ;D

PS Looks good Phil.

[Big_unit]

Me Five.

Cheers
James

[McCod]

Looks good... but ya still limited by the volume or capacity that ya water pump can pump... only way you will get a pressure drop across the inlet is if the water pump can pump more than your hose can get thru the orifice... would be the go if ya had very low flow and or pressure feeding it.
But with most domestic water supply over 25 psi and a fairly high volume thru a 12mm hose it should not be a problem. Also outboard waterpumps are designed to operate "suck" at atmospheric pressure
Not knocking it... as i said it looks good ;)

Cheers Les

[Billo]

can jam a muff either side of my keel any day ....that WOULD seriously increase the pressure though ....wouldn't want to blow a hose too early ;D ;D ;D

[Fishin_Dan]

can jam a muff either side of my keel any day ....that WOULD seriously increase the pressure though ....wouldn't want to blow a hose too early #;D ;D ;D

Billo - I thought it was supposed to go on the "leg" in the middle.... ;)

[gogecko]

OK, Ive heard the attempts to explain it, but Im still with Blaze. I only did yr 12 physics (so I'll defer to you if you are a plumber), but simple physics says that the pressure going in doesnt change with the split into 2 hoses.

As for the arguement of backpressure being reduced, there is still water escaping from both muff seals, AND out thru the top of the engine. That arguement would only make sense if you plugged the top outlets. So sorry BAssman, I cant agree with you. I am willing to listen if you can explain it better tho.

as Dr Karl syays "do the experiment". This one needs to be measured to see if there is anything to this. Wheres the Ausfish mythbusters?

[szopen]

I make my living designing, installing, solving problems, modifying and playing with pipes. Pipes for water, air, ammonia, liquid nitrogen, gas, milk, ice cream, chocolate, all the works...

I would maybe be able to offer a bit better explanation if somebody explanied what does this thing actually do.

If I understand correctly this is a water connection hose where water goes in through the two black "muffs" at the top of the picture, than through two hoses, Y joint and than out somewhere. What makes water go into the "muffs" a pump? What is after the Y joint?

[Hoges]

I make my living designing, installing, solving problems, modifying and playing with pipes. Pipes for water, air, ammonia, liquid nitrogen, gas, milk, ice cream, chocolate, all the works...

I would maybe be able to offer a bit better explanation if somebody explanied what does this thing actually do.

If I understand correctly this is a water connection hose where water goes in through the two black "muffs" at the top of the picture, than through two hoses, Y joint and than out somewhere. What makes water go into the "muffs" a pump? What is after the Y joint?


BTW that is one wet muff! lol

You ask, "I would maybe be able to offer a bit better explanation if somebody explanied what does this thing actually do."

Okay it is used to attach to the bottom of your outboard leg when you want to flush out the motor after a day out in salt water.

By attaching it to the water intake of the OB leg it allows the impeller to pickup fresh water and flush out the salt water whilst running the engine on dry land.

IMHO as pretty as Luck-Phill's design looks I don't think the amount of pressure required needs to be that great.

As long as there is enough water for the impeller to pickup to flush the engine is available then no amount of extra pressure is going to assist any further. Pressure should not come into it just the amount of water being there to be picked up by the pump.

That should be there with the normal muffs. Again IMHO

[gogecko]

HI szopen, you sound like the guy we need to tell us.

Salt tends to build up in the water cooling passageways, if its not flushed out regularly. The hose is attached to a common garden tap at the other end. The bottom of the outboard is a double sided intake valve. The top is an impeller/water pump and outlet valve, as Hoges said.

The other common method is to fill up a rubbish bin with water, immerse the bottom of the outboard in it, and turn the engine on. As Hoges said, we dont really need pressure because the water pump impeller should suck it up.

The Y hose connection looks like a good idea, I am just wondering if/why it is any better than a single sided muff.

[szopen]

OK I think I am getting the picture.

Garden hose is connected to the bottom of the Y joint, than water goes through two hoses, two muffs, muffs are plugged into the water intake openings of the outboard leg, water goes into chamber with water pump impeller inside, than through the cooling system of the motor and out.
During use the motor is running so the water pump impeller works.

A couple of facts about pumping water (apply to most liquids as well).

1.
Water pump will give a flow rate that is in reverse proportion to the pressure drop in the piping downstream, this pressure drop will be the water pressure at the pump outlet (only for water systems with an open outlet).

For example: same water pump will give a flow rate of 2 cubic meter an hour if a pressure at the outlet is 6.5 bar and a flow rate of 8 cubic meter an hour if a pressure at the outlet is 2.5 bar (sample numbers from a pump flow curve).

What it means is that with the same source actual flow will depend to a great degree on the pressure drop downstream of the source.
Total pressure drop will be a sum of pressure drops across all the parts of the system.

2.
If we are talking about a situation when the flow is actually closed somewhere downstream of the pump, than with the pump running (and no actual flow through the system) the pressure at the pump outlet will be equal to maximum pressure of the pump.

3.
A centrifugal water pump works like a flow accelerator meaning it sort of adds to the flow rate, in most cases the pump impeller is not really sealing the pump chamber so the actual flow rate through the system will be a sum of flow rate resulting from action of the impeller and resulting from the water flow caused by pressure at the pump inlet.
Pump simply adds pressure. For example if I have a pump capaple of adding 3 bar pressure but I have a sufficent water flow and a pressure of 2 bar at the inlet the outlet pressure can be 5 bar.

Based on the points above.
With a domestic water supply lets say at 5 bar, the water pressure at the end of the hose will be equal to:
1. If the hose outlet is closed (no actual flow) = domestic water supply pressure.
2. If the hose outlet is open (have flow) = pressure drop downstream.

So why would a double muff work better than a single muff?
1. With two hoses after the Y joint pressure drop between the Y joint and the water pump chamber is smaller resulting in a smallet total pressure drop and larger flow.
2. With a pressure drop downstream of the outboard water pump being same at all times (so the water flow rate caused by action of the pump impeller constant) additional flow will be a result of water flowing "around" the impeller, this flow caused by more water at higher pressure supplied through the muffs.

Hope this all makes sense.

Actual result can be tested in a very simple way.
Direct the water outlet from the outboard into a bin.
Run the motor with standard muff setup, chac how long does it take to fill the bin.
Run with double muff and check the time again, if shorter the actual water flow is higher.

[Lucky_Phill]

Jeez there is some technical data flowing here.

OK, I have no research to back up why I do this, but I know one thing.

I used to flush outboards with muffs ( standard ), and since ( credit goes to Dave ) hearing about this ' rig ' I have been using it.

I have noticed a substantial increase in the amount of water exiting from the ' tell tail ' of the motor when the D/muff is connected. Also notice more water exiting from tell tail when motor is switched on.

SO< as far as I can gather, there is more water and water pressure being exhurted into the motor , via the impellor, thus producing a better FLUSH !

Jeez, it was only a pic.

Phill

[blaze]

Hi Phil
yeh
I probable start the rot but could not see the benefit of d/muffs, never doubted but could not understand from my limited education
cheers
blaze

[szopen]

So if more water is coming out at least some of the theories are right ;)

What I have written in posts above comes from practical experience not formal education.

[Outsider]

I had a second black spring from an old pair of muffs lying in the garage. After seeing Foxys post months ago I put the 2nd spring on but kept the single sided outlet. Makes a world of difference with much faster telltale spray startup and a harder stream, but without all the extra hose and connections. Obviously just seals better with more water forced into the leg inlet and less sneaking down the sides.

[Mr__Bean]

G'Day guys,

Got nothing to add on the technical side, but on my 225 Yammy 4 stroke it never has the same amount of water flow out of the tell-tale when I use muffs compared to when the motor is idling when the boat is in the water.

Mind you the amount that comes out of the tell-tale has never been like the flow I used to get out of my 200 Black Max Mercury, but when the boat is in the water I certainly get a constant flow.

However, when I use the muffs, water sprays out the sides everywhere (we have very good water pressure here), but it still doesn't flow out of the tell-tale like when I am on the water.

My theory is that the little plastic grill on the water pickup on each side of outboard leg has holes that are too fine for enough water to enter from one side only. I reckon this is the key, not what the hose pressure is here or there, but can enough water get in through those holes from one side only.

Yes, yes, I know water comes out the other side as well when using single hosed muffs, but I don't think it is the same as having an equal pressure on both inlet grills.

So, I will be buying another set of muffs and making one up as shown because at the moment my tell-tale hole just dribbles and blows bubbles like a 2 year old, but it piddles out water when the boat is in the drink.

Oh, one last thing, after hearing how many people end up leaving their muffs on and cooking there engine when out on the water I will be fitting a long red streamer to it also.

- Darren

[sjp]

all i know is i still find a dribble of dried up salt crystals somewhere on the bottom leg after i've flushed my 60 yammie with the muffs and with the top hose flushing unit on the motor , i just wonder how effective flushing really is

[Stu]

Me six.
Cheers
Stu ;)

[FNQCairns]

So what is the answer people?

Is the total waterflow/volume greater at the end of the muff pieces now there are two exit holes so now doubled in exit area but still only one inlet (to the appartus at the Y piece) so half the diameter of the muff pieces combined.

I think no extra volume but cannot back up why :-[

[bidkev]

We're all small cogs in a big engine. I think the big cogs would've invented the double muff by now if it *really* made a difference. Is it sold commercially and if not, why not?

My new donk comes with muffs that attach via a rod threaded through the intake which is used to pull the muffs tight into the leg. I get no water escaping from these muffs as I did with the bog standard muffs so I assume that indicates that the pump is capable of sucking more water if you have a tighter fit? Or do the tight fitting muffs simply prevent water from escaping and the excess water is simply "backing up". Can't test by the outflow from the engine because I never experienced the outflow with standard muffs.

cheers

kev

[The_Walrus]

I would think that most water taps would deliver enough presure. The problem seems to be the how well the muffs fit on your particular outboard leg.

Either a stonger spring or adding an extra one should compress the muffs tigher onto the leg and reduce water loss. With tigher fittings muffs, you may only have to turn the tap on half instead of full.

Having said that, I prefer to flush my yammi by using a plastic tub.

Luc

[Lucky_Phill]

A local Yammie dealer in Brisbane has advised all his 4 stroke motor purchase'rs to flush in tub, and NOT using muffs.

mmmmmmmm ??????///

Phill

[szopen]

Possible reasons for this recomendation (based on some of the posts above):

1. Potential damage to the cooling system when water pressures is too high as a result of tight fitting domestic water supply connection.
2. Potential damage to motor when the muffs are forgotten and left on.

Some other issues.
Small crystals left after flushing: tap water also contains a certain amount of minerals (salts) and if all the water evaporates (drys out) some residue will always remain.

Better flushing.
When using a tub it might help to use warm water and maybe add some of the salt removal cleaning chemicals.

[noodles]

Simple hey blaze i am with you dude

[MrWong]

[sup][b]A local Yammie dealer in Brisbane has advised all his 4 stroke motor purchase'rs to flush in tub, and NOT using muffs.
mmmmmmmm #??????///
Phill
I agree with you phil ! have to say that I have heard more than one dealer say go the flush bag option rather than the Muff - Phil #you are then man - I think a flush bag is the go and possible more effective at saving water ??? #I am no expert but - cheers one and all!
::)

[bidkev]

[sup][b]A local Yammie dealer in Brisbane has advised all his 4 stroke motor purchase'rs to flush in tub, and NOT using muffs.
mmmmmmmm #??????///
Phill
I agree with you phil ! #have to say that I have heard more than one dealer say go the flush bag option rather than the Muff - Phil #you are then man - I think a flush bag is the go and possible more effective at saving water ??? #I am no expert but - cheers one and all!
::)

The danger with bins and flush bags is that the salt that you are flushing out then lands in the bin and goes through the engine again........admitted, it is a lot more dilute, but salt, nevertheless.

cheers

kev

[gogecko]

OK Ive changed my mind now that Ive heard the evidence. If Phil says it comes out the top stronger, then thats a deal. Well done Phil. Thanks to szopen for the real world experience.

Some boat ramps dont have taps, so I also use tubs at home, and I find the outflow misses the tub. A standard size rubbish bin from bunnings fits very nicely.

[Fishin_Dan]

As another link to the chain then, what if you have a new E-Tec (Or will when the boats finished) and they have the hose clip on the motor you just clip the hose straight onto... You just then turn the hose on. Don't even need to start it... ::)

[Oldyella]

This setup is good for the new Merc/Mariner ELPTO which have an extra water pickup under the cav plate and a low pressure/hi volume impeller. Any leakage from the conventional flusher will just about stop the flow to the block. I made one one these and it works better on my OB.