Mercury 3.3hp 2 Stroke - No water through Tell Tale.

[lustyd]

OK I've had another look. How sure are you that this should spin clockwise? For the record, the shot of the impeller in the housing shows it wanting to spin anti-clockwise from the top, and given where the impeller compresses that would seem correct.

 

[VicS]

That jet needs explaining but my outboard pushes water out through gaps in the front/sides and is clearly intended to do so possibly just that. Looks like quite a powerful jet, though, so quite suspicious.

There's a very simple test, if the OP puts his finger over that hole to stop the sideways stream and all of a sudden water starts to shoot out of the tell tale, that's conclusive.

Do you reckon he will be able to get a finger in there and reach the hole?
.

 

[Polybus]

The suspicious stream was obviously something I looked into.

It comes out of a hole that looks very "factory made". It is perfectly round and positioned pretty much exactly in the middle on the right hand side of the Water Pump Housing. I suspect it is a vent hole, but I will still test it.

But there are two ideas above that I will check out.

I will try it with a clear tube, to see how high a head of water it will produce - as rightly questioned - I need to know if the pump has enough "ooooomph" to push water all the way up to the PowerHead. I have "sortakinda" done this test, but did not make a video of it. I took the PowerHead off, attached my drill to the top end of the Drive Shaft and turned the drill on. A nice steady stream of water came out of the top of the water tube, and started filling the water galleries - but I concede the Pumps job gets harder from that point on, so I will still try the Clear Poly Tube test and see how I get on.

As to the parts - I fitted genuine Tohatsu parts (this engine is a rebadged Tohatsu) - did not replace the housing liner - it looked very good.

I will try the "put my finger over the hole" test. But I will only be able to get my finger over the hole with the Leg off the engine. I will test it like that, and if the stream out of the water pump significantly increases, I my try covering the hole with tape, or similar, reassemble the motor and try it again.

If that doesn't work.....

I have found a whole gear box, including the water pump, for sale at a fair price, I may buy that (its not much more than a new Pump Housing Liner) and swap the whole thing over and see how that goes.

Surely a whole new water pump will fix it.....

Mind you, if the new one works fine, I can guarantee you this old, non-functioning one will end up back on the motor and a whole bunch more tests will occur until I discover the source of the problem.

Like most people on here - I am convinced it is the water pump somehow.

I mean really - its not that complex - Liner - Impeller - really, that's it! But its got me well and truly beat!!

 

[Mark-1]

Do you reckon he will be able to get a finger in there and reach the hole?
.

I confess I thought there was easy access when assembled. From the op's latest post below there's clearly not.

So there's not the simple test I imagined available. Still worth blocking it with a cocktail stick or something to see and understanding what it's there for.

 

[VicS]

OK I've had another look. How sure are you that this should spin clockwise? For the record, the shot of the impeller in the housing shows it wanting to spin anti-clockwise from the top, and given where the impeller compresses that would seem correct.

Certain

 

[lustyd]

Certain

Which would push water towards the inlet on the left hand side, which is covered with the gasket, wouldn't it? Looking at the pictures the compressed vanes would be the opposite side to the inlet/outlet?

 

[lustyd]

never mind, I just realised. I did say I was confused today! In which case the impeller is the wrong way in the pic of it in the case

 

[lustyd]

You know, the more I look at this the more I'm convinced the shaft needs to spin the other way. Water will definitely enter via the port side and flow into the hole on that side. It then needs to spin to the starboard side, get squeezed down the hole and back to the open hole on the right side of the gasket to flow up and out of the pump. doesn't it?

 

[Polybus]

RE: the stream of water from the side of the Water Pump.

Check out this picture - it is a close up of the Lower Base of the Water Pump. That is the hole that emits the water. So I am sure it is supposed to be there, but I will still do the tests.



This question made me investigate further - I had not considered the condition of this Lower unit - to be honest, I did not even realise it was removable - even during the rebuild I only gave a token effort at removing it - I thought it was part of the gear box housing and forcing it would lead to breakage.

Here is another view of it...but from below.



I wonder what the condition of those seals I can see is like - perhaps THEY are the root of all evil.

 

[lustyd]

That seems a really likely candidate. Could be the hole is for lubrication with sea water, but if the pump loses pressure through that seal then water will escape. I didn't realise those were removable either!

 

[VicS]

I wonder what the condition of those seals I can see is like - perhaps THEY are the root of all evil.

The seal you can see in the Lower half of the pump housing is the oil seal for the shaft entry into the gearcase. If it is bad you will get water into the gear case. It would be a good idea to replace it while it's accessible

 

[VicS]

You know, the more I look at this the more I'm convinced the shaft needs to spin the other way.

If you want it to spin the other way you will have to redesign the recoil starter and modify the ignition system . You will also need to fit a left handed propeller or the boat will only go backwards.

 

[Polybus]

OK - new results.

1: I have connected the output from the Water Pump (where the brass water tube normally connects) to a clear PVC Pipe and strung it up the wall - about 4 times higher than the engine itself. When I spin the drive shaft with a drill, water quite easily reaches all the way to the top and sprays out the end. When I block the little hole on the side of the Water Pump, water sprays out the top about twice as strongly.

2: I have tried a completely different head and run the engine - still now water flow from the Tell Tale.

3: I have tried a completely new Water Pump - different Water Pump Housing, different Impeller, different liner - still no Water from the Tell Tale.

4: I have taken the gear box off the engine - connected a hose to the Water Pipe - started the engine up and then sprayed water from my garden hose into the engine's Water Pipe - I get a nice strong flow from the Tell Tale (and the engine seems happy about it!!)

5: I have run the engine with the little hole in the side of the Water Pump Lower housing blocked with a Toothpick - still nothing from the Tell-Tale.

So what does all that tell us???

Answer - There is NOTHING WRONG with the cooling system!!!

So thinking about it (which can only end in tears)

We KNOW the water pump is working fine - I have tried two different ones, and they both pump water up vertically to about 3 meters.
We KNOW the system is not blocked - when I attach the garden hose water flows well through the system and out of the Tell Tale.

Other salient facts.

Exhaust is coming out of the Tell Tale.

I have began to start wondering if something to the following is happening.

Fact 1: The Water Pump is pushing water up the Water Tube well.
Fact 2: There is Exhaust coming out of the Tell Tale.

I am beginning to wonder whether there is some mechanism where the pressure of the exhaust is competing with the pressure of the water being pumped up by the Impeller - with the Exhaust pressure being much higher, and thus preventing water flow up the water pipe, but (obviously) ONLY when the engine is running.

I have changed the head and changed the head gasket - just in case pressure is coming from the combustion chamber and leaking into the Water Jacket - and then in turn down through the whole cooling system thus preventing water flow.

I have take the Power Head off (yet again) and checked the gasket and put gasket sealing compound all around the help the gasket seal.

Still no water flow from the Tell-Tale when I start her up.

Could it be possible that the exhaust pressure is acting "like" a blockage of the system to prevent water flow?

Can anyone suggest a test to check this out.

As mentioned above - I have attached a garden hose to the bottom of the water tube while the engine is running, and that shows good water flow from the Tell Tale, but I am assuming the garden hose delivers quite a lot more pressure than the water pump, and it is quite difficult to control the garden hose pressure at low pressure to give it a good test.

Once again I find myself at the mercy of the collection Forum Brains to come up with better ideas than me.

You guys have been such a great help so far - and I hope the Forum Members are learning a lot from this - I certainly am!!!

And I suspect we may be getting near a solution.

 

[VicS]

Exhaust pressure causing it ???????????????????

Check the relief port on the leg is not blocked. I guess on this one its just below the bottom swivel .

Main exhaust outlet not blocked ?

You said earlier that you had it immersed to at least 10" above the anti-ventilation plate. Try raising t until only about 4" above the AV plate.

 

[lustyd]

You have 3m head of water so a tank at 3m supplying to your poly hose will supply pressure the same as the pump. You can syphon from a bottle or washing up bowl to avoid complex plumbing. This will test the pressure from hose question.
Very impressed at your perseverance!

 

[Polybus]

Raised it to about 4 inches above AV plate - nothing.

Put the AV plate pretty much at water level and apart from getting much much louder, as the exhaust was pretty much flowing to open air (given the exhaust bubbles) - I reckon I saw a few spits of water from the Tell Tale.

Certainly not a flow, and perhaps just my wishful thinking, but I reckon there was just a few little, and I really do mean little, spits of water.

Not sure what that means though.

Relief port is clear - no problems there.

Main exhaust outlet?? Not sure what you mean by that - the exhaust port opens up directly into the Space between the power head and the Midsection - it looks clear. There are certainly a lot of bubbles coming out of the bottom of the leg - so I think the exhaust is coming out OK, but I suspect some exhaust pressure may be seeping into the cooling system.

 

[Polybus]

You have 3m head of water so a tank at 3m supplying to your poly hose will supply pressure the same as the pump. You can syphon from a bottle or washing up bowl to avoid complex plumbing. This will test the pressure from hose question.
Very impressed at your perseverance!

Im not sure what you mean by this.

Can you explain it clearer please for the dummies (me) in the audience.

 

[Refueler]

Thought I'd go down the boat and make a little vid of my J3 ... so here it is ...

Note that the flow is actually better than my larger 4.5 Twin .... markedly better !! But less than the other O/bds I have.

I know its not same brand etc. but all the O/bds in this size even if not the Tohatsu base - should be similar in results... geared or not.

 

[lustyd]

Im not sure what you mean by this.

Can you explain it clearer please for the dummies (me) in the audience.

No probs. One of your issues is that your hose doesn't actually mimic the pump pressure. To make the "hose test" more realistic you need a hose at the same pressure as your pump produces. Since you now know for sure you can pump up to 3m that demonstrates the pressure of the pump. Placing a container of water at that height will deliver identical pressure through a hose back to the engine for testing. Obviously you probably don't have a handy container with a connection for the tube, so I suggested a syphone. If you use the same bit of poly tube you used to test the height it could pump then put the end in any container of water at that height and syphon (suck the other end until the water starts to run). You will then effectively have a hose providing the same water pressure and probably similar flow as your pump produces. This test will prove there are no blockages which are enough to stop the pump but not enough to stop a hose. It's not a big test, but it might rule out a few more things.
Hopefully that's explained what I meant, more than happy to expand. It's definitely feeling like a blockage in there somewhere or a poor seal but I can't even guess where that might be so it'll be more and more specific tests from here on in!

 

[VicS]

Raised it to about 4 inches above AV plate - nothing.


Main exhaust outlet?? Not sure what you mean by that - the exhaust port opens up directly into the Space between the power head and the Midsection - it looks clear. There are certainly a lot of bubbles coming out of the bottom of the leg - so I think the exhaust is coming out OK, but I suspect some exhaust pressure may be seeping into the cooling system.

The underwater outlet behind the prop

If there is no water flow exhaust gas can flow bacwards theough the cooling system from the leg and come out of the telltale

PS It took me a few moments to work out what Lusty was saying

Ive copletely run out of ideas as to what is wrong with your motor