Yanmar 1GM10 impeller

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navrep

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My boat is still on her mooring in the marina.
Today I wanted to check the impeller for my 1GM10 for damage, I had bought the boat in April this year. Managed to get the cover off and the impeller out and checked happily - and no obvious degradation. However I can not get a decent seal, to stop water coming through.

Initially I just put it back on but when I turned the ball valve for sea water it started dripping. Second time I replace the gasket with yanmar part and also applied gasket grease - it seemed to hold until I started the engine, then I started spraying water. I turned the engine off.

Does the gasket have to be fitted a particular way round? Any help greatly received as I am new to boat ownership - and thought this should have been a fairly simple bit of maintenance!!
 
Hi,

I've checked/changed my 1 GM impeller several times, and never had that problem. As for the gasket, I cut out my own from a .5mm sheet of PTFE, so it is re-useable. Are you sure you have put the cover on the way you took it off? that is to say, you haven't turned it 'inside out'. It could make a difference.
 
navrep said:
My boat is still on her mooring in the marina.
Today I wanted to check the impeller for my 1GM10 for damage, I had bought the boat in April this year. Managed to get the cover off and the impeller out and checked happily - and no obvious degradation. However I can not get a decent seal, to stop water coming through.

Initially I just put it back on but when I turned the ball valve for sea water it started dripping. Second time I replace the gasket with yanmar part and also applied gasket grease - it seemed to hold until I started the engine, then I started spraying water. I turned the engine off.

Does the gasket have to be fitted a particular way round? Any help greatly received as I am new to boat ownership - and thought this should have been a fairly simple bit of maintenance!!
Click to expand...
get a tube of blue hylomar in your tool kit. A paper gasket is all a pump needs + a drop o hylomar
 
Hmmm, well I think I did - I will try the other way around - when I first checked it I left the bolt behind the pulley attached and swivelled the plate out of the way - but as this leaked I though it best to replace the gasket. I guess it is possible at this point I got it back to front but it did look like the wear of the impeller was on the inside.
 
I used blue coloured Volvo gasket grease (what it actually was I can't remember) which had been left by previous owner - and looked like it had been previously used on the plate.
 
Never had this trouble although there is a very slow leak which gives some salt encrustation around the join. Never found out how to cure this although I suspect that some gasket goo (or a PTFE gasket as noted above) might sort it.

Yes there is a right way round for the gasket, if you look at the pump body you can see that it is carefully shaped and I assume that the gasket should be positioned to follow this shape although I don't know if this is essential or just a question of keeping things neat and tidy.

As for spraying water - I'm a bit baffled. It's possible that the outlet pipe is blocked in some way, but if the engine has been running OK that doesn't seem likely.
 
navrep said:
My boat is still on her mooring in the marina.
Today I wanted to check the impeller for my 1GM10 for damage, I had bought the boat in April this year. Managed to get the cover off and the impeller out and checked happily - and no obvious degradation. However I can not get a decent seal, to stop water coming through.

Initially I just put it back on but when I turned the ball valve for sea water it started dripping. Second time I replace the gasket with yanmar part and also applied gasket grease - it seemed to hold until I started the engine, then I started spraying water. I turned the engine off.

Does the gasket have to be fitted a particular way round? Any help greatly received as I am new to boat ownership - and thought this should have been a fairly simple bit of maintenance!!
Click to expand...

It sounds as if the cover is distorted assuming that you are nipping up the bolts sufficiently. Take it off and rub it across some fine wet & dry on top of a piece of glass. Once you start rubbing you will soon see if it is flat by looking at the abrasion marks.

A better long term solution is a Speedseal if they do one for your pump as this uses a rubber ring and large thumbscrews and seals more easily.

Richard
 
RichardS said:
A better long term solution is a Speedseal if they do one for your pump as this uses a rubber ring and large thumbscrews and seals more easily.

Richard
Click to expand...
+1 I fitted a speed seal when I had a 1GM10. Makes life a lot easier especially if the impeller should fail...how do I know this !
 
navrep said:
My boat is still on her mooring in the marina.
Today I wanted to check the impeller for my 1GM10 for damage, I had bought the boat in April this year. Managed to get the cover off and the impeller out and checked happily - and no obvious degradation. However I can not get a decent seal, to stop water coming through.

Initially I just put it back on but when I turned the ball valve for sea water it started dripping. Second time I replace the gasket with yanmar part and also applied gasket grease - it seemed to hold until I started the engine, then I started spraying water. I turned the engine off.

Does the gasket have to be fitted a particular way round? Any help greatly received as I am new to boat ownership - and thought this should have been a fairly simple bit of maintenance!!
Click to expand...

Where is it dripping from? It might be the pump seal that has gone rather than the impeller.

If (hopefully) it's dripping from the impeller housing, then turn the engine by hand while inserting the impeller so that it seats correctly.
 
Last edited:
Thanks for advice - I would be surprised if it was the pump seal as there was no issue before I tool it apart! Just thought I should check to see what state the impeller was in , and also thought a good idea to have a play when it was not vital.
 
Remind me .... can a 1GM10 cover be refitted in more than one position. If so, it is possible the surface has warn in a way that it only seals in one position?

Also, if operating in shallow sandy water, 1GM10 water pumps soon begin to leak from the trace hole. Are you certain it wasn't leaking before you removed the cover?
 
Are you tightening the screws by the approved method? Nip them all up then tighten diametrically opposite sides a bit at a time. The only way I can imagine you could get a leak of the size you describe is by tightening hard on one side before the other.
 
navrep said:
Hmmm, well I think I did - I will try the other way around - when I first checked it I left the bolt behind the pulley attached and swivelled the plate out of the way - but as this leaked I though it best to replace the gasket. I guess it is possible at this point I got it back to front but it did look like the wear of the impeller was on the inside.
Click to expand...

You haven't bent the face plate have you with leaving the screw in ? I know it's pretty unlikely. From memory you can flip the face plate around on this pump to offer up a new unworn face to the impeller. also check outlet jubilee clip hasn't been disturbed and the water is running down.

As a quick improvement on my last boat I replaced the small bronze screws with longer stainless screws, I knurled a bit of 1/2" brass rod around 3/4" long, drilled and tapped it through its centre then using lock-tight screwed the new longer stainless screws right through. You could then undo them with your fingers. As you will know the screw behind the pulley is a pig to get at with a screw driver.
I believe you can get just the knurled screws from speed seal now .
pete
 
I believe you can get just the knurled screws from speed seal now
They're quite a price though.
I had a new brass faceplate made for mine with a O ring groove and cheese head Allen key fixings. (Speedseal don't do a replacement to fit my pump)
I was wondering too if you have accidentally bent the plate. It should have impressed marking with the model number on the outside. Well mine does anyroad.
 
As already suggested a Speedseal is the answer to leaky front plates on that engine. It is a really bad bit of design with silly little bolts, one hidden behind the pulley. The slightest leak and the oil pipe underneath corrodes and the front timing cover gets eaten away. That was the only thing that ever went wrong with my 1GM and no more leaks after fitting a Speedseal.
 
Thanks everybody - I think the most likely thing I have done is got it on back to front or similar - first attempt was I am sure because the original gasket was pretty much gone, so when I tightened it was dripping, quite fast - I know I didn't pay enough attention when I took it off completely (live and learn) so that is probably where I have gone wrong. Next time I am up I will swap it all around - 1 in 6 chance!

There are only 3 bolts on the pump.

Didn't bend the plate as bolt was loosened and swivelled easily.

The last time I was up the engine had cut out on first two attempts of starting, then got going with initially some black smoke but then seemed to clear - I changed the air filter this time up as it appeared to be pretty dirty. So maybe a more sinister problem - hopefully not!

Once again thanks for all the comments - and I will look into the speed seal.
 
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