Sea water leak - Yanmar 1GM10 pump

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Grahamm462

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I have discovered a leak from the pump body where it connects to the engine casing. This is the unit that holds the impeller. According to the workshop manual there is a O ring between the pump body and casing.
Have any forum members experienced the same problem and how was it overcome ? Is it just the O ring ?
 
The O ring seals the pump body to the engine block. If that has failed then oil will be leaking from there.

BUT within the pump there are two seals, one seals the water part of the pump and the other is an oil seal.
Ususlly, and I expect the pump on the 1GM10 is the same, there is a telltale hole in the pump body between the seals so that you are alerted to a water leak before it forces its way past the oil seal into the engine sump.

However if all you see is a small oil leak from that O ring then that should be all that requires replacing. I might be a good time while it is off to renew that to overhaul the pump ... replacing those other seals. and inspecting the bearings.

Do be sure that the leak is from the O ring, not coming from the telltale hole in the pump body.

Worth making sure that the mounting bolts are tight!
 
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Sorry I failed to notice that you said "seawater leak" in the title

Nothing to do with that O ring. It is the water seal (#9 in the diagram I am looking at) in the back of the pump body.

No way of telling if it will just continue to drip for ages or suddenly get worse.

You do not want it to become so bad that it forces water past the oil seal into the engine sump or to damage other items that it drips on to.

Sensible therefore to sort it out sooner rather than later.
 
Yes, fix it immediately. Not only do you run the risk of seawater dripping on the oil pipe and corroding it, but you will get further corrosion of the aluminium housing and the steel set screws. This area is a horrible mixture of metals - bronze pump housing, stainless shaft, aluminium housing and mild steel screws holding it all together. Add seawater and you get the picture. Guess how I know!

So, have the pump overhauled - seals and bearings are easy to change and the Yanmar dealer should do it for the price of the parts if you are not confident to do it yourself. Replace the gasket and the O ring and fit a Speedseal cover. Make sure there are no leaks from the hoses when you put it back toegether and you should have an idiot proof set up and easier impeller changes.
 
My bet is most 1GM10 water pumps weep water to some extent. If you have an older boat with messy bilges or do not have good access to the water pump you may not notice until the oil pipes begin to corrode.

If you have super clean bilges with shiny gel coat, as I did, you notice every drip ... very annoying. I gave my oil pipes many coats of paint virtually from new + a smeer of vasoline to protect them. In the solent where the water is sandy they only remain totally water tight for 50 to 100 hours after a full rebuild with a new shaft and seals.

It is a relatively easy job best done by removing the pump on a Sunday evening and taking it home to rebuild. The shafts are expensive. If there is a grove I beleive there is some scope to reposition the seals to avoid the grove.

No great hurry assuming it is only an occasional drip ... just make sure you look after the pipes underneath.
 
Do sort it out, my steel oil pipe was pitted so £55 was passed over to replace it with a genuine yanmar replacement. They have now changed their conecting pipe to copper, all supplied with no paint, thats how I noticed. My problem was a weeping hose not the pump but with the same outcome.
 
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