Annoying Leak.

[vptech]

have a look at the waterpump with engine running, also pull the impeller out and have a look at the seals they are nearly allways rusted, its a bit of a hack job but you can pull out just the front water seal with he right pick and once greased up you can carefully punch the new one in with a 19 or 20 mm deep socket otherwise you will need to pull the whole pump press out the shaft and change both seals. also check the shaft for wear when its out. use Volvo grease. I have to do the full job at work but on friends boats I don't bother. Its very common for these to leak that badly I probably changed 10 last year on md engines, first step it to pull the impeller. also the water system is so small on that engine its only one heat exchanger so there are not to many hoses to check, also look at you exhaust system properly if its been cold and frozen water has split something. I am starting to see some unbelievably useless and shocking advice here (not on this thread btw) which prompted me to join the forum in the first place.

 

[Tranona]

I'd start by running the engine while tied to a pontoon or quay. First with it in neutral for a while to check for water if none then in gear to eliminate prop shaft seal. If it's only when motoring then it almost has to be engine or prop shaft seal. If you get it running in neutral then it eliminates your shaft seal.

It is a saildrive so no prop shaft seal.

 

[Spirit (of Glenans)]

Have decided to man up and stop being a total wuss about engines.

I can't see where I can possibly go wrong doing my own service on the damn thing and whilst at it I'll have the water pump shaft out and change the seals too. I've found a replacement water trap too - so will change the whole shebang and exhaust hose and see if that helps - if nothing else it will give me some peace on mind.

Only change one thing at a time, test and if negative result change something else.

 

[Uricanejack]

I have an annoying leak 2.
Similar volume run the engine for a while the bilge needs pumping. Mine is the water pump. At first I thought it was just the seal as it started just after I had the engine serviced. Volume, I suspect the bearings may be shot, anyway removal and a rebuild are scheduled as part of my winter work list. Delayed due to sending away for rebuild takes a while.

Just a daft idea to check, can you slide a dry absorbent pad under engine, run briefly pull it out and see if there is a wet spot and what it corresponds to.
I'm not a mechanic or engineer but I have heard one say, "Check and eliminate the easy stuff first".

 

[Flica]

I have an annoying leak 2.
Similar volume run the engine for a while the bilge needs pumping. Mine is the water pump. At first I thought it was just the seal as it started just after I had the engine serviced. Volume, I suspect the bearings may be shot, anyway removal and a rebuild are scheduled as part of my winter work list. Delayed due to sending away for rebuild takes a while.

Just a daft idea to check, can you slide a dry absorbent pad under engine, run briefly pull it out and see if there is a wet spot and what it corresponds to.
I'm not a mechanic or engineer but I have heard one say, "Check and eliminate the easy stuff first".

Interesting that you feel compelled to send your raw waterpump away for replacement of seals and bearings (as it's as big a job to do one as the both on the two waterpumps I've had)
With the frequency of leak, that the raw-water cooled Yanmar 2GM suffered with its Jabsco pump I got in the habit of carrying a spare pump. To take off the faceplate meant you had to dismount it!!
The far superior Johnson pump on the 3YM goes much longer between replacement impellers (about 500-700 hrs), but I still have a spare pump.
The only real problem is extracting the bearing, but I've found that if the impeller has gone, the seal is not far behind and the bearings go as soon as the seal leaks.
Rather than buy the replacement pump as a Yanmar, I bought the bits from Johnson with a cost of about 20% (that included body and shaft) of the Yanmar derivative. On coming to the pressed steel pulley (an engineering miscarriage) I had to cough up more than the rest of the parts had cost.
Though it now only takes about 90" to change impeller, (changing the water pump only involves two bolts, not 6 as does taking off the faceplate).
I can then re build the pump, at my leisure, in stillness and using relevant tools such as a vice.

 

[SiteSurfer]

have a look at the waterpump with engine running,

This is one of the annoying issues (bought an endoscope to help look) as its not possible to view the bit i need to see due to a bulkhead.

also pull the impeller out and have a look at the seals they are nearly allways rusted, its a bit of a hack job but you can pull out just the front water seal with he right pick and once greased up you can carefully punch the new one in with a 19 or 20 mm deep socket otherwise you will need to pull the whole pump press out the shaft and change both seals. also check the shaft for wear when its out. use Volvo grease.

If I understand that correctly, you are suggesting leaving the oil seal alone and just picking out the water seal visible from the front without removing the pump? If that's the case then the endoscope may come in handy! Otherwise until I get back to the boat and look, I don't actually have any idea how complicated it is to remove the water pump as a unit - I'm pretty sure there's 4 bolts but not sure if 2 of them are behind the unit.

I have to do the full job at work but on friends boats I don't bother. Its very common for these to leak that badly I probably changed 10 last year on md engines, first step it to pull the impeller. also the water system is so small on that engine its only one heat exchanger so there are not to many hoses to check, also look at you exhaust system properly if its been cold and frozen water has split something.

I don't think that this has ever been done on this engine. The boat is in Pompeii so not overly convinced that freezing is an issue.

Thank you for your input, along with everybody elses it allows a bigger picture to be built up, and being 200 miles away from the boat - a lot of armchair diagnostics have to be done - which I appreciate infuriates people.

 

[Mistroma]

In my experience the majority of leaks in boats are via the raw-water pump (or its piping) - next in order of frequency are leaking exhausts, less frequent leaking stern-glands.
As has already been pointed out a drop every 10" is a leak of 18 litres an hour.
I've assumed the OP can confirm the leak is of salt, not fresh water.
If it's fresh water look at the freshwater piping, but first check by turning off the FW pump.
Looks as though he's started at the least likely and is moving, irresistibly to the more likely.

Not certain where you saw that 1 drip every 10 seconds is 18 litres in an hour. That would make a drip 50mls.

I seem to remember that small drips were much smaller than 1ml when checked the gland on my old boat. No such thing as a British Standard drip but largest will be well under 50 mls.

A rapid drip might be 3 litres per hour but 300 mls would be more like it. My old stern gland leak was about 30 mls per hour with engine running and nil when sailing.

 

[Flica]

This is one of the annoying issues (bought an endoscope to help look) as its not possible to view the bit i need to see due to a bulkhead.


If I understand that correctly, you are suggesting leaving the oil seal alone and just picking out the water seal visible from the front without removing the pump? If that's the case then the endoscope may come in handy! Otherwise until I get back to the boat and look, I don't actually have any idea how complicated it is to remove the water pump as a unit - I'm pretty sure there's 4 bolts but not sure if 2 of them are behind the unit.


I don't think that this has ever been done on this engine. The boat is in Pompeii so not overly convinced that freezing is an issue.

Thank you for your input, along with everybody elses it allows a bigger picture to be built up, and being 200 miles away from the boat - a lot of armchair diagnostics have to be done - which I appreciate infuriates people.

Don't mess around - if you're doing the job yourself it will take about 15" more to exchange the whole lot - if it's abelt-driven pump there is no oil-seal, just the waters seal.
As it's impossible to get a boat to Pompeii, it gas to be in Torre Annunziata, Castellmare or in Marina di Stabia itself. There is, in the marina, a very adequate marine mechanic who will do the job for you in about an hour and about €18. Providing you take hime the dismounted pump.

 

[Leighb]

May not be relevant to your arrangements, but many years ago we chartered a Sigma 33 which turned out to have significant water ingress, but only when the engine was running. It turned out to be from the water inlet hose which was in contact with the propshaft coupling and a tiny hole had been chafed through. Was very tricky to find, especially on a strange boat.
Just to make matters worse, neither of the two bilge pumps fitted actually worked.

Easy enough to fix once the cause had been identified.

 

[SiteSurfer]

Don't mess around - if you're doing the job yourself it will take about 15" more to exchange the whole lot - if it's abelt-driven pump there is no oil-seal, just the waters seal.
As it's impossible to get a boat to Pompeii, it gas to be in Torre Annunziata, Castellmare or in Marina di Stabia itself. There is, in the marina, a very adequate marine mechanic who will do the job for you in about an hour and about €18. Providing you take hime the dismounted pump.

The engine in question has a shaft driven water pump (MD2010).

I blame the spell checker for my geographical blundering, thankfully my marine navigation is a touch more reliable as I am able to work out where I am using the normal road atlas.

I meant of course Pompey.

 

[SiteSurfer]

May not be relevant to your arrangements, but many years ago we chartered a Sigma 33 which turned out to have significant water ingress, but only when the engine was running. It turned out to be from the water inlet hose which was in contact with the propshaft coupling and a tiny hole had been chafed through. Was very tricky to find, especially on a strange boat.
Just to make matters worse, neither of the two bilge pumps fitted actually worked.

Easy enough to fix once the cause had been identified.

I've placed myself in some awkward positions peering at various hoses whilst the engine is plodding along, its only a top down view and luckily (or perhaps not so luckily) all the water action with hoses et al, happens in a relatively close proximity to each other. Visibly - and of course allowing for the bulkhead that neatly gets in the way of actually seeing the lower part of the water pump - the only thing that I have thus far observed has been the drip from the hose attached to the water lock (mentioned in the OP) - its been really comforting to know that the possibility of a water leak from the water pump is in fact quite possible, it gives me something else to check - naturally I'll do one thing at a time and see what results.

The only small issue right now is that the boat is on the hard making long term tests tricky, however - I'm confident that the leak is not hull based so all this can be done when refloating.

 

[Spyro]

It is a saildrive so no prop shaft seal.

He said he'd checked the stern tube.???

 

[VicS]

He said he'd checked the stern tube.???

OTOH he said he has an MD2010/120S and that the sail drive gasket is OK

It's difficult to help someone who is not sure if he has a sail drive or a shaft drive but I'd start by checking the raw water pump and the exhaust system

 

[SiteSurfer]

He said he'd checked the stern tube.???

Once again I fall foul of the lexicon of marine terms, I'm referring to a tube inside the stern which carries the rudder post. So to my undecucated and decidedly non seadoggy eyes its a stern tube.. cos it's well... a tube - at the stern.

 

[SiteSurfer]

OTOH he said he has an MD2010/120S and that the sail drive gasket is OK

It's difficult to help someone who is not sure if he has a sail drive or a shaft drive but I'd start by checking the raw water pump and the exhaust system

Pretty sure I'm confident about the whole saildrive thing. At least unless the boat fairies have been in.

 

[VicS]

Once again I fall foul of the lexicon of marine terms, I'm referring to a tube inside the stern which carries the rudder post. So to my undecucated and decidedly non seadoggy eyes its a stern tube.. cos it's well... a tube - at the stern.

You confuse us all by referring to the "rudder tube" in your opening post!

 

[SiteSurfer]

Edited OP to avoid further embarrassment.

 

[Lizman]

Non-bonded stern tube? A lot worse when motoring for obvious reasons.

Good luck with finding it.

 

[solent clown]

So glad this thread is about a boat and not prostate problems.
Other than that I have absolutely nothing obvious to add. Maybe a diagnosis trick might be to use a bucket of coloured water in place of the raw water inlet , that way at least you might isolate it to the engine/exhaust rather than another part of the boat.

 

[SiteSurfer]

So glad this thread is about a boat and not prostate problems.
Other than that I have absolutely nothing obvious to add. Maybe a diagnosis trick might be to use a bucket of coloured water in place of the raw water inlet , that way at least you might isolate it to the engine/exhaust rather than another part of the boat.

That. Is genius.