Engine flushing - do you run your engine?

bernithebiker · 28 September 2007, 17:27

I'm curious as to whether you old hand RIBbers run the engine or not when you flush it.

Assuming the boat is out of the water, and you are using the hosepipe adaptor to flush, do you run or not? Looking back through some old posts here, it seems Mercury say you can choose whether or not to run the engine. But Yamaha tell you not to. It seems that you could seriously damage your rubber water impeller if you do, as it is getting either no, or very little water to it, and it will overheat.

Presumably, if using muffs there is no danger, as the water is forced up past the impeller under pressure.

But, if you do not run the engine, then the thermostat will be closed (unless you flush very soon after getting the boat out of the water). Therefore, you will only be flushing a portion of the cooling circuit, and not the majority, the important bit all around the head.

Does this make sense, or am I talking rubbish?!

ian parkes · 28 September 2007, 17:45

Quote:

Originally Posted by bernithebiker

I'm curious as to whether you old hand RIBbers run the engine or not when you flush it.

Assuming the boat is out of the water, and you are using the hosepipe adaptor to flush, do you run or not? Looking back through some old posts here, it seems Mercury say you can choose whether or not to run the engine. But Yamaha tell you not to. It seems that you could seriously damage your rubber water impeller if you do, as it is getting either no, or very little water to it, and it will overheat.

Presumably, if using muffs there is no danger, as the water is forced up past the impeller under pressure.

But, if you do not run the engine, then the thermostat will be closed (unless you flush very soon after getting the boat out of the water). Therefore, you will only be flushing a portion of the cooling circuit, and not the majority, the important bit all around the head.

Does this make sense, or am I talking rubbish?!

Thats exactly what I was told by 2 dealers now , flush with muffs until the water runs warm out of the exhaust then you know the thermostat is open and the whole system is getting flushed .
Maybe some engines can flush without running but I can't see how .

Carl · 28 September 2007, 17:46

use muffs,tickover only,and you will have no problems

Andy Moore · 28 September 2007, 18:10

Quote:

Originally Posted by Carl

use muffs,tickover only,and you will have no problems

What do muffs do?

Jono · 28 September 2007, 18:12

Quote:

Originally Posted by Andy Moore

What do muffs do?

.....keep yer lug 'oles warm....

bernithebiker · 28 September 2007, 19:18

Muffs are the large rubber suction clamps that go over your water intakes.

They then connect up to the hose pipe.

The Yamaha ones that I have do not work very well. They are supposed to clamp onto the engine leg by spring power alone, but the fit is not tight enough and alot of water leaks out before it even gets into the engine.

The last time I tried to use them, I was getting a telltale jet, but only a weak one. The engine beeped from overheating so I shut it down. My boat shop advised me to tape over the other large grille a touch higher up - a water outlet I believe, but this didn't help much.

Therefore, I went back to the direct hose connector at the top of the engine. BUT, cannot (or at least not supposed to) start the engine in this mode.

Andy Moore · 28 September 2007, 19:28

Quote:

Originally Posted by bernithebiker

Muffs are the large rubber suction clamps that go over your water intakes.

They then connect up to the hose pipe.

I think my Mercury is flushed by connecting the hose right by the cowling. What would one do with the muffs in this instance?

bernithebiker · 28 September 2007, 19:53

You either use muffs OR the direct hose connector (if you have one).

I don't think you can (or should) use both at the same time, but you would need two hosepipes (or a 2 way hose splitter) for that anyway.

My question really relates to using the DIRECT hose connector. Can you / do you run your engine when using this? It seems that if this direct connection is high up the engine, near the cowling (like Yamaha), not enough water will reach your water impeller (which is usually down low on the engine leg) and could damage it if the engine is running.

Andy Moore · 28 September 2007, 20:32

Do the muffs in any way muffle the sound of the engine if you are running it out of the water? I imagine it must make one hell of a racket.

Or is that a stupid question?

jyasaki · 28 September 2007, 21:07

Quote:

Originally Posted by bernithebiker

I'm curious as to whether you old hand RIBbers run the engine or not when you flush it.

Depends on what method you use to get water to the engine.

Using muffs and the in-water (for normal running) cooling water pickups, run the engine for long enough to get the thermostat open (which realistically shouldn't take all that long.) You need to make sure that all water intakes are covered (duct tape for the ones that aren't covered by the muffs. On a small Honda, there are a total of 3: One on either side of the leg, and one on the bottom of the anti-ventilation plate. Don't know about others, as I use the hose connector now, so haven't looked.)

Using a hose adaptor on/near the head of the engine, generally you do not run the engine. Input is after the thermostat, so the heads entire water jacket is flushed.

Some manufacturers may have differing instructions (For instance, the leg-mounted hose adaptor on Suzuki's are given a choice to run or not.)

Pretty much what everyone else said, I'm afraid.

Andy: It does usually get a bit loud whenyou're running on muffs. Nowhere near as loud as, say, a Harley wrapping the engine up, but not something you want to do in the wee hours of the morning, either. Tilting the motor up so the water pools in the prop hub *may* help attenuate the noise a bit, but not much.

Berni: You probably won't damage too much running off the direct connection (impeller doesn't need all that much water to self-lube), but why chance it? It's designed to flush using water pressure alone. Running the motor won't accomplish anything since you don't have enough water at the impeller to pump anything, so the only freshwater circulation you're going to get is due to water pressure (i.e. exactly the same as if it was not running.) You may add a bit of heat which will help get salt into solution, but that's not that hard to do anyways. Salt dissolves pretty well in fresh water.

jky

Cypman · 28 September 2007, 21:14

My understanding is that on modern engines you may have two flushing options:-
1. Muffs on the water intake which requires the engine to be running on idle in order to pump the water around all the engine. This is the best method of flushing the waterways but requires a good flow of water and close fitting muffs to ensure adequate cooling.
2. A hose fitted directly to the flushing point, usually located on the side of the main motor. This must be used without the engine running as the water pump/impeller is not getting a flow of water which acts as a lubricant and as a consequence will quickly be damaged. I would only use this facility when option 1 is impossible eg when the boat is afloat in a marina berth and the engine is tilted out of the water.
No doubt others have different views!!!

bernithebiker · 28 September 2007, 22:29

Quote:

Originally Posted by jyasaki

Using a hose adaptor on/near the head of the engine, generally you do not run the engine. Input is after the thermostat, so the heads entire water jacket is flushed.

jky

Thanks for that good information.

If you are right that the direct hose connector is after the thermostat on my Yamaha 60, then that makes good sense, and no, absolutely no need to start the engine.

But is that 100% sure? Is there a complete separate cooling circuit for the direct connection? If so, then this must be the best and most thorough way to flush.

(When I flush like this, engine off, water comes out of the bottom of the engine leg, through the prop and the water intake - how does it get past the closed thermostat?!)

jyasaki · 29 September 2007, 05:56

Quote:

Originally Posted by bernithebiker

Thanks for that good information.

If you are right that the direct hose connector is after the thermostat on my Yamaha 60, then that makes good sense, and no, absolutely no need to start the engine.

But is that 100% sure? Is there a complete separate cooling circuit for the direct connection? If so, then this must be the best and most thorough way to flush.

(When I flush like this, engine off, water comes out of the bottom of the engine leg, through the prop and the water intake - how does it get past the closed thermostat?!)

Well, if you want it from the horses mouth, go to the Yamaha website and read the owners manual. It's written by the guys who designed the engine, so they should have a pretty good grasp of correct procedures.

http://www.yamaha-motor.com/outboard...d_manuals.aspx , and enter the year and model.

And realistically, if the water source is after the thermostat, the only parts not flushed are the impeller housing, and the water tube leading to the thermostat. Not really a lot to wear there (and all pretty much vertical, so it's not going to pool and evaporate, which is where most of the salt buildup comes from.)

No separate cooling circuit with the hose adaptor at the powerhead; it's just an opening into the circuit that is normally pressurized by the impeller (try undoing it for a brief moment while running; you'll probably get a bit wet, though.)

jky

BogMonster · 29 September 2007, 18:15

Quote:

Originally Posted by Andy Moore

Do the muffs in any way muffle the sound of the engine if you are running it out of the water? I imagine it must make one hell of a racket.

Or is that a stupid question?

Quite a sporty exhaust note on my Johnson, especially if you blip the throttle

Guaranteed to get the attention of neighbours and indeed anybody else within 1/2 mile

RibinSpain · 30 September 2007, 14:09

I have a 2006 Yam 80 4 stroke & after much research & many different opinions, flush with direct hose connector whilst cleaning down boat (say 3 mins or so), then, hook up the muffs & give it another 3 mins or so idling.

Maybe a bit OTT but the salt is v corrosive here in Spain & I plan to keep the boat & ob in tip top condition.

When flushing via direct hose connector there is water egress from lower leg so I think there is a bypass mechanism, or backwash, which cleans out the impellor & thermostat. Otherwise, why would Yam fit such a connector if it only did half a job.

Anyway, lots of diff opinions & views as usual.

Nos4r2 · 30 September 2007, 22:17

Quote:

Originally Posted by RibinSpain

When flushing via direct hose connector there is water egress from lower leg

Which parts of the lower leg?

9D280 · 01 October 2007, 12:05

On my Suz there is a small amount of water down the prop exhaust - I assume it is because when you're running flat out the amount of water needed to cool the engine will not all get through the tell-tale nozzle (the name gives it away, otherwise it would be called the cooling outlet?) and the easiest place to dispose of it is down the leg and out through that nice big hole in the middle of the prop. Also when afloat the static pressure at the prop results in the exhaust leaving above water thru' the silencer, but the coolant that isn't exiting via the tell - tale has to go somewhere - take it out the water and that back pressure isn't there, hence why the tell tale isnlt so forceful?

My prop has a flared trailing end to the hub, I assume it's to act in a similar manner to a "wedge" self bailer, create a slight vacuum in the exhaust and either pull more coolant through or get the exhaust out the cylinder quicker (probably a bit of both).

For what it's worth I have discovered I can put my hand over the prop exhaust (fingers clear of blades!) and it makes no difference to idle speed (same as it being underwater) - also makes the muffs a far more sociable method of flushing! (this winter's plan is a wooden bung with a small vent hole or two to keep it quiet next season)

jyasaki · 01 October 2007, 16:45

Quote:

Originally Posted by Nos4r2

Which parts of the lower leg?

F115 has water coming out all over the damn place. Telltale, through-hub, and about 10 or 12 little jets or dribbles from all kinds of openings on the leg (some that I didn't even know existed.)

jky

RibinSpain · 02 October 2007, 16:09

yes that´s the same on the f80, lots of water egress points when hooked up to direct hose connection as previously posted here. Tell tale, through prop, small hole at leading edge of gearbox, plus many others.

Starting to think that it pretty much flushes everything or it wouldn´t have been fitted - Yam are no fools. Anyway, till I hear otherwise I am going to keep flushing via the muffs too.

Nos4r2 · 02 October 2007, 18:16

Quote:

Originally Posted by 9D280

On my Suz there is a small amount of water down the prop exhaust - I assume it is because when you're running flat out the amount of water needed to cool the engine will not all get through the tell-tale nozzle (the name gives it away, otherwise it would be called the cooling outlet?) and the easiest place to dispose of it is down the leg and out through that nice big hole in the middle of the prop. Also when afloat the static pressure at the prop results in the exhaust leaving above water thru' the silencer, but the coolant that isn't exiting via the tell - tale has to go somewhere - take it out the water and that back pressure isn't there, hence why the tell tale isnlt so forceful?

My prop has a flared trailing end to the hub, I assume it's to act in a similar manner to a "wedge" self bailer, create a slight vacuum in the exhaust and either pull more coolant through or get the exhaust out the cylinder quicker (probably a bit of both).

For what it's worth I have discovered I can put my hand over the prop exhaust (fingers clear of blades!) and it makes no difference to idle speed (same as it being underwater) - also makes the muffs a far more sociable method of flushing! (this winter's plan is a wooden bung with a small vent hole or two to keep it quiet next season)

It actually sounds like you need a new impeller fairly soon. The telltale should get stronger the faster you're going and there should be quite a lot of water coming out of the prop hub.