Impellor - Am I being dumb?

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Pasarell

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I put off changing my water pump impellor because it's so difficult to get at. I know that's dumb anyway - but am I going about it the wrong way?

Engine is a (Kubota) Hydromarine DM12 and the pump is on the rear right side of the engine, just forward of what I assume is the flywheel housing. Gap between the housing and pump face plate is about 2cm.
Just to add some spice I have to remove the bulkhead between the quarterberth and engine compartment to get at it and then lie down using my left (wrong) hand.

Gap in front of face plate means even the smallest right angle screwdriver I've found won't fit so I used long nosed plyers to undo the screws - from their condition what previous owners have done too.

Whole job took about 4 hours. Glad I did it as one of the fins had broken off and was being swept around inside the pump.

Everything I've read says I should be able to replace the impellor in minutes out at sea. I went into a marina to avoid the slight movements on my berth at the top of Southampton water and still took hours.

I imagine a Speadseal will help but am I missing something else?

Anyway engine now runs smoother, quieter and cooler.

All comments on how to make next change easier are welcome. There has to be a better way!
 
Wow! I couldn't put up with that! I'd be replumbing to resite the pump to make the faceplate accessible, even if it was via an access hatch in the bulkhead.
 
I have a poroblem accessing the impellor on my Perkins 4107..it is actually the only bit of the engine which is difficult to get at.

After looking at the problem from various angles I am going to cut a hole through the bulkhead from the saloon, behind one of the fwd facing seats. This will give me access to the engine 'hole' right in front of the impellor housing.

I sure this is not suitable for you but what Im saying is that possibly with a bit of 'outside the box' thinking there may be another approach.

PS Im going to get the speedseal securing bolts also.

Regards Nick
 
I tried to do that but only had access to one of the securing bolts. The other I couldn't get a spanner onto let alone turn it in the space available.

Project for this winter is to put an access hatch in the bulkhead but that's the easy bit ....
My concern is trying to change the impellor in any kind of sea.
 
You're not alone - I have the same problem and there is no workaround that I can see. I think that when push comes to shove you would do it at sea but you might need to keep quite a few spare screws, a spare cover, etc. because it would be very easy to drop one. For my Yanmar, the recommended change period is every 500 hours and I don't do it more frequently than that. I do run the engine every few weeks in winter (we are liveaboards) so the problems of frozen and deformed impellors is not an issue.
 
as other have said, it is well worth making alterations so that you can inspect and change impellors easily. Relocation of teh pump sounds a bit drastic, and I am not sure how easy that would be. Certainly get yourself a Speedseal, they are pricey but well-worth the money. I now check the impellor as frequently as I check oil levels.
 
Could you remove the pump first - I need to on my Yanmar ....

PS next time you need a calm berth - dont go to as marina, come to Marchwood Yacht Club. We welcome visitors, a fraction of the price and bar etc etc!
 
Discovered how hard it is to get at on my HT6354s, did S/H one at Burnham a couple of weeks back. Whoever last did it did not change the screws for the cover, which were knackered and needed a Molewrench to move them. Had to undo the pich bolt and remove the pump in the end. I think Mr Speedseal may be getting some money from me soon. Two hours of cursing and fiddling, time which could better have been spent in the dinghy or a pub. I didn't change the screws either, local chandlery had nothing that fitted. Bring home and tap M4 methinks.
And the impeller was fine:-(
 
Itr may appear a bit drastic to relocate the pump but in my vue that would be the only way to go.A pulley driven Jabsco or Johnson pump could be adapted to the front of the engine in some way.
 
Would it be an idea to discard the screws and replace them with stainless steel thread pieces (don't know the english word, maybe studs? You can buy them per meter and it is basically just a veeeeeery long screw with no head) and put the cover on using wing nuts?
 
[ QUOTE ]
Itr may appear a bit drastic to relocate the pump but in my vue that would be the only way to go.A pulley driven Jabsco or Johnson pump could be adapted to the front of the engine in some way.

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Totally agree, lets face it if you HAVE to replace impeller at sea, in a chop, at twilight on the way in, what kind of nightmare job would that be?
Relocate the pump, put it somewhere that it is easy to access, not jut to change the impeller but also to inspect it, cos lets face it, if it is such struggle to get at the only time you will take the cover off is when it is too late and you are forced to replace a shattered one. I never like doing jobs that are forced upon me.
Bite the bullet and move the pump, always assuming there is somewhere to move it to!
Mal
 
[ QUOTE ]
Bring home and tap M4 methinks.

[/ QUOTE ]If you do that you won't be able to use Speedseal. New screws are obtainable along with new covers and usually, if used with care, with an appropriate screwdriver, they last the life of the cover.

Mind you, some folks inspect their impellors very often. I suspect that messing about like that increases problems and that you are best advised to simply replace at the recommended service interval.
 
'Stud' or 'studding' is the correct word for a length of threaded bar. If you do that you might find it more difficult to get the impellor in or out, you would need to think that through, and try it out before loctiting it in.
 
Another perspective on this is to consider impellor repair as simply not possible at sea. There are plenty of other things that all into that category (head gasket, etc.) and you have no doubt got contingency plans for that. e.g. sail in, anchor off, call Seastart (is that excellent organisation still going?). If you are a Mobo you probably have two engines (I would) and a sailor seldom needs to consider calling the CG or emergency services.
 
I have wondered about that. How closely matched to the engine does the pump need to be? Is there a danger of too big a pump pushing too much water through and causing water to back up into the manifold ? At the other extreme, how likely is it that it won't provide sufficient cooling? I guess the thermostat provides some leeway?
 
It does not answer the removal of the impellor problem but I would go for cap head screws that you can use an allen key on. Mor positive location and better leverage than a screwdriver.
 
Thanks all. Some very useful suggestions. I think I will investigate moving the pump first and driving it with a belt.
I didn't mention getting the impellor out as it was relatively easy after the screws but I still wouldn't fancy trying it in a seaway. I could just get a bit of grip on the top of the hub with long nosed pliers. No chance of getting a remover onto it and consequently no chance of the impellor being reusable.
If I fit a belt driven pump does it matter about the shaft just rotating with no load on it?
Thanks again
 
Repair of an impeller should be possible at sea, and the Speedseal makes life a lot easier, as long as there is reasonable access.

One point we have found is that the impeller is often hard to remove if it has been in a while. Speedseal supply a small tube of a silicon type lubricant for the neoprene O ring between the cover and the pump housing with the kit. They also recommend putting some on the impeller shaft for easier removal of the impeller in future. They provide a small plastic lever to assist with removal, but we've never found it much use - not so much of a worry if you're simply pulling out a shredded impeller in a hurry, but a nuisance if the impeller is OK.

As a result we bought a proper impeller puller - not cheap, but does the job quickly and effectively.
 
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