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

Before you skip the OB here's something that may help....

Drop the leg off and block the exhaust (ensuring the exhaust port is sealed), remove the water pump impeller and then refit the pump and the leg.

Extend the tell tail with a pipe and funnel and pour coloured water (food dye?) in. It's possible you may see a leak somewhere but if nothing comes out of the leg's water intake then it proves you have a blockage somewhere.
 
Thanks Clanger. I'm heading out to the town where I left the outboard today (4 1/2 hour drive). If my mate hasn't got to the bottom of it, I'll give this a try.
 
Well - the latest update.

(Really sorry for the length of the post - go grab a cup of Tea and settle in.....)

Still out here in Western NSW and have spent pretty much the whole day watching my mate torment himself with this engine.

He had an air of confidence about him when he put the new impeller in, but it soon disappeared when it failed to pump any water out of the tell tale. He looked rather crest fallen.

But it only served to make him attack with renewed vigour. But all he did, was repeat all the tests I have done many, many times, testing everything from the water inlets at the bottom, to the tell tale hose at the top. All tested good, but still no water from the tell tale. He even pulled the gear box/water pump off and replaced it with the new one (the same one I used to test it a few months back), but still no result.

But there are now two avenues of investigation.

One:
When he was pulling his hair out, I suggested we take the gear box off, and attach a hose to the bottom of the Water Tube, so he could watch the water flow well out of the Tell Tale, just to prove the path was clear. (He has a really handy gizmo to attach the garden hos to the water tube so there were no leaks)

We did that, and the fact that the water flowed so well out of the Tell Tale, even at very low hose pressure, seemed to surprise him.

Now the interesting part.......that same test was performed, with the same hose pressure and as far as we could manage it, all things being equal - EXCEPT - with the engine started. No flow from the Tell Tale!!

The test was repeated - with the engine not running - nice strong water flow from the tell tale - then, leaving everything connected and leaving the water running, we did nothing else but start the engine - the flow from the Tell Tale stopped!! We turned up the garden hose pressure and were rewarded with a nice steady flow from the Tell Tale.

This reminded me of a theory we were working on quite a while back, that somehow exhaust gases were leaking into the water jacket, and building up enough pressure to prevent the water flow coming up from the water pump.

So two theories:
  1. The water pump is not providing enough pressure/volume to reach the top of the engine
  2. The exhaust is somehow leaking into the cooling system, preventing water flow
My gut feel is No: 1 - and I feel it is supported by the fact that we often see either Steam or Exhaust emanating from the Tell Tale. And because were have tried 2 completely different water pumps, on two completely different lower legs, and neither of them work, new impellers, used impellers, nothing works. It would be very unlucky to have two completely different water pumps failing mysteriously after both have been fully rebuilt.

Second:

I am not so convinced about this one, but my mate had some doubts.

He was pretty happy that the water pump was pumping out sufficient water - and he has a lot of experience with outboards.

When we were pumping water up the water pipe with the garden hose, he was surprised by the amount of water flowing back down the inside of the leg, there was quite a volume running down the leg before the Tell Tale would start to spurt water.

He was wondering if somehow there was a part, some kind of a plug, missing inside the water galleries at the bottom of the power head.

So - once again - off with its head.

Came apart OK, Gasket looked good in all places, in tact, with no evidence of any low by anywhere..

However there is one spot )sorry, should have got a photo - I will next time)- to describe it its on the top of the mid section (not the power head itself), in the water galleries, and located at the very end of the water galleries. So water comes up the water pipe, into the water galleries the flows around one side, through a whole leading up to the water jacket, through the water jacket to the other side of the engine, and then back down into the opposite side of the water galleries, along that final channel and down through a surprisingly big gap and into the interior of the leg and then out the bottom.

So I guess that gap is there to allow water to flow out the Tell Tale, and whatever does flow out through the tiny opening for the Tell Tale, can escape out the bottom of the engine - thus keeping the water flowing and cooling, rather than stuck, waiting to be forced out of the tell tale.

Anyway - he felt there might have been a part missing from that spot, some small part which somewhat restricts water flow out of that opening.

I got a bit excited at this revelation - I thought Yes!!! That's why the original engine was seized, too much water was flowing out here, no cooling to the top end and BANG!! You may recall I put a completely different Power Head on because the original couldn't be saved.

He played around trying to put things into that gap with restricted the flow of out going water - all to no avail......

So after all that.......complete failure once again.

So as it turns out, Mike-1 was right all along - the engine is haunted. Now my friend agrees.

I have another one of these engines (another 4 in fact) and one of them is at home completely stripped waiting for a new piston and rings, so when I get home, I am going to have a good look at the mid section of the leg, the water galleries in particular to see how that water gap looks in there.

In fact here is an idea!!!!

Before I reassemble the engine I have at home, I will take the mid section of the leg out to Western NSW and test out this motor with a new mid section - just to see if the water galleries, or something around the water galleries is broken/missing/leaking etc....

But that results in a real philosophical question.......

I already have a new Power Head and I already have a new Gear Box - the only major group lest is the Mid Section of the Leg.

Lets say I put a new mid section on it, and then it works - have I fixed the outboard, or given that I have replaced all the parts, have I just built a new one????

If I put a new mid section of the leg in, and it doesn't work......perhaps it might be time to give up!!! (NEVER!!!)

Thoughts??

Exhaust pressure?
Too much water flowing back down the leg??
Something else?
 
Just another quick note - when we were pumping water up the water pipe with the garden hose - with the engine off, nice flow out of the tell tale - with the engine running, flow stopped. We were able to start the flow again by turning up the pressure on the garden hose, but we had to turn it way up! To a pressure way beyond what I believe any water pump could produce.

While on the face of it, you may feel this test indicates the water pump is not working sufficiently, we felt that the amount of pressure we had to turn up on the garden hose to get water from the tell tale is way above what the water pump could be expected to produce.

And remember, now we have tried two completely different water pumps, both with new rebuild kits in them, with new impellers, and I doubt they are both completely dead......

:mad:
 
Polybus said:
Just another quick note - when we were pumping water up the water pipe with the garden hose - with the engine off, nice flow out of the tell tale - with the engine running, flow stopped. We were able to start the flow again by turning up the pressure on the garden hose, but we had to turn it way up! To a pressure way beyond what I believe any water pump could produce.

While on the face of it, you may feel this test indicates the water pump is not working sufficiently, we felt that the amount of pressure we had to turn up on the garden hose to get water from the tell tale is way above what the water pump could be expected to produce.

And remember, now we have tried two completely different water pumps, both with new rebuild kits in them, with new impellers, and I doubt they are both completely dead......

:mad:
Click to expand...
This sounds as though back pressure from the exhaust is stopping the water flow ........... but that's ridiculous. If the back pressure was that high I doubt if the engine would run
Anyway with the gearbox assembly removed I don't see how back pressure could build up

It's either a vital clue as to what's happening or a complete red herring

Edit: Just read your long post at #83. I didnt see that initially

When you are feeding water in from a hose and start the engine running are you still getting plenty of water coming down the inside of the leg ? That's not stopping along with the tell tale is it ?
 
Last edited:
Shoulda bought a Seagull if you wanted reliability like that!
I agree; it's haunted. Burn it.?
On the plus side though, at the end of this you'll be a leading authority on the type. (y)
 
VIC: Sorry for the late replay - there always seems to be lots of water coming down the inside of the leg, Engine Running, or Engine Not Running,

That's it!!! Despite all my assurances I would never surrender......

I GIVE UP!!!!

I just can't figure it out.

My last hope is you guys.

You may remember a friend of mine took a look at this outboard - he's not a numpty like me - he owned and operated his own small engine/mower/outboard store for 40 years. He is now 77 and retired. But he had a look at it and everything he came up with also failed.

His last suggestion was perhaps there is some small part missing from inside the power head that is allowing too much water to fall back down inside the leg, and not enough to flow up into the water galleries around the cylinder (which is where the tell tale originates). The theory being with the engine not running, the water can get up into water galleries around the cylinder, but with the engine running, the exhaust back pressure prevents the water from getting up to the water galleries around the cylinder. But he freely acknowledges that it has been a long time since he has worked on these types of engines and cannot really remember what goes where.

I agree with previous comment by Vic:

This sounds as though back pressure from the exhaust is stopping the water flow ........... but that's ridiculous. If the back pressure was that high I doubt if the engine would run
Anyway with the gearbox assembly removed I don't see how back pressure could build up
Click to expand...

My last, desperate hope is that there is some part missing (I have put 2 new gaskets on it) in the powerhead which is letting exhaust gasses get into some space where they should not be, and hence stop the water flow. This might be just some small "leak" which is small enough to let the engine run, but big enough to stop the water flow.

Unlikely I know, but I am desperate and depressed.

My intention now is to take a serious of close up photos of the inside of the power head and post them here, hoping that someone might see something obviously missing.

My worst fear is that someone here will instantly say - ah yes - see that piece there, that is the problem.......

How embarrassing that would be after all this time. ?
 
If you block exhaust holes on leg will all exhaust and water go out tell tale ? I am starting to believe exhaust is going both ways.
 
Aussie farmer said:
If you block exhaust holes on leg will all exhaust and water go out tell tale ? I am starting to believe exhaust is going both ways.
Click to expand...
You would have to block the main exhaust outlet as well for that to happen but possibly the exhaust back pressure will kill the engine
 
I have just come to this thread having scanned through. Quite entertaining but very frustrating.

The problem remains that you have plenty of waterflow without the engine running. It is killed with it running.

You have efficiently ruled out faults with water pump and delivery.

Your problem seems to be hidden in the power head. The leg is basically an Exhaust pipe with a drive shaft and a water tube running through it.

I would suspect a small hidden crack in the power head that is opening under compression. I don't know this model but are all the waterways essentially in the head? This leak will either be in the head or in the power block if it has water ways.

I would try to fit a thin solid plate between the head and the block instead of a gasket. Pressurise the combustion chamber with brake fluid or atf through the spark plug hole and see if you get any leaks out of the waterways of the head.

If no leaks then your problem is in the block not in the head.

If there are interconnecting waterways into the block from the head now drill through the solid plate to connect them to block and repeat test.

If you get a leak then your block is snafu.
 
I'm back!!!

And I still haven't got this thing working.

This thing has me completely beat, and I've given it a rest for quite some time, simply because I couldn't think of anything else to try. But now......

I've got a virtually identical outboard I've been working on lately - and it works fine - but while I was working on it, I had an idea for a test I had not done on my "haunted" engine.

So the engine with no water through the tell tale is all together and has been sitting in the corner of the shed for over a year now, just mocking me.

Today I got it out, put it in a water tank, fuelled it up and started it - it started quite easily - but of course no water from the tell tale.

I pulled off the cowl, fuel tanks and pull starter - and removed the spark plug to remove compression.

Then I put a drill with a nut driver onto the Flywheel nut and span it - WATER FROM THE TELL TALE!!!! Not a huge amount, but a decent flow, and the drill wasn't going that fast - so I'm pretty happy with the flow I got.

But that proves a lot of things:
  1. The entire water system is clear with no blockages.
  2. It is drawing water from the water surrounding the leg
  3. The Water Pump and Impeller are working well
  4. Water is being pumped up out of the Water Pump and though the Water Tube
  5. Water is circulating around the water galleries around the crank case
  6. Water is being pumped up into the water galleries around the barrel/cylinder
  7. The Tell Tale pipe is clear because waster is streaming out of it.

This is fantastic news.

BUT.....

As soon as I start the engine - Nothing. No water from the tell tale, regardless of how high the revs are.

Engine Off - Water from Tell Tale.

Engine On - No water from tell tale.

Nothing else changes.......

Does that give anyone any clues - because I still can't figure it out.
 
I just did another quick test.

Same as the above, with the Drill on the FlyWheel nut and spinning the engine, but this time with the Spark Plug in place.

So it was building up back pressure, "exhaust" bubble were coming out the bottom of the Leg - and the was still water flowing from the Tell Tale. Perhaps slightly less than before - but also the drill was turning slower because it had to fight the Engine Compression.

But again - start the engine. NO water from Tell Tale.

I'm starting to remember why I through this thing in the back of the shed and ignored it for over a year.
 
Repeated the test again, this time with a nice big electric drill rather than my gutless little cordless drill.
Even with the Spark Plug in place, and fighting against the compression, the drill got high revs.

And after about 10 seconds I was rewarded with a good, solid, consistent water flow from the tell tale. A nice high flow.

Started the Engine - No water from Tell Tale.

Pfffffft.
 
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