Mercury 8hp

[xeitosaphil]

Hi all,
Just about to do a yearly service and wondered if I should replace the impeller while I'm at it?
It hasn't been changed now for about 4 years . Everything is as it should be ,water comes out as a constant stream even at tick over but some marine places say you should replace every year or two? Not sure if they are looking for work or should it be?

I have a new impeller should I have too,but I don't see the point of trying to strip the lower leg unless it is really necessary. If things are ok leave well alone I have always thought, but am I just being lazy?

Do they usually replace all the gaskets etc as well when they do it, or is it ok just to replace the impeller itself?

If I needed replacement gaskets can I buy them online? any ideas from where?

Any advise welcome Philip

 

[VicS]

This website should locate UK dealers for you http://www.mercurymarine.co.uk/enginechoice.php

This (US) website has parts diagrams.
http://www.crowleymarine.com/index.cfm

You dont give the year or model details so have not attempted to look at the parts that might be involved but be prepared to renew any O rings or gaskets that you may disturb.

Your call really on the pump. 4 years life is reasonable but many last a lot longer.

Bit late to be doing the annual service. It should have been done as part of the winter layup procedure, then you have all winter to do any necessary repairs

If there's any sign of water in the gear lube while the gearcase is off to do the pump is the time to replace seals etc
Do not reuse seals on the filler and level plugs.

Wills Marine http://www.willsmarine.co.uk/ have been found to be good for Johnnyrude spares and are also Merc dealers.

Owners manual if you have mislaid yours available on line from the download center at http://www.brunswickmarineemea.com/homepage/welcome

Wills marine is conveniently located for you but www.ronhalemarine.co.uk advertise regularly in our favourite comic

 

[xeitosaphil]

Hi Vic ,

Thanks for your reply, the engine is a 1998 and I think a Belgian export to the UK.
The reason I haven't done the service before is I have been sailing through the winter as the weather has been quite good at times.

I haven't drained the oil yet so don't know about the water in the oil but storing the engine prop downwards I see there is some oil draining out of the bottom of the leg behind where the prop fits .Could this mean that the oil seal has gone on the prop shaft? and if so , is this the type of thing I can replace or does it require pullers etc and need to be done by a marine engineer? I am quite an able type but do not have any specialist marine puller type tools.
I have managed to down load a full PDF file on the engine from America with all the QEM part numbers and exploded veiws for the whole engine just need a supplier in the Uk for individual parts by part numbers . I would like to be aware of the costs and availability of parts etc before starting.
Any idea of what it might cost to have the impeller fixed by a dealer?

Thanks for info already received and additional? Philip

 

[VicS]

Cant help with what the costs would be at a dealers as I do all my own maintenance.

Pump impeller change is fairly straight forward usually, seals a little more complex but no rocket science involved.

There should no problems getting spares for an engine as young as that and any authorised dealer should be able to tell you prices.

The oil you see leaking. If it is obviously gear oil (that smells foul and is pretty viscous) then yes you have seal gone and from what you say it would probably be the prop shaft seal(s). There are also seals on the vertical drive shaft below the water pump and a seal of some sort or an O ring round the gear shift rod.

BUT if that's a 2 stroke engine it would be normal to see partly burnt oil from the fuel seeping out around the lower unit. That would be black and smell burnt or of petrol.

 

[xeitosaphil]

Vic,

It is a two stroke engine but the oil looks to be a dirty yellow, greeny colour which suggests it could be from the prop shaft oil seal.
If it is this one thats gone, does the cowl - casting - unit it fits into, which the propshaft passes through , is this threaded so could be unscrewed? or is it a press fit which would mean it needs pulling out, basically do you think I could do it myself or would it mean a trip to the dealers, along with the usual masive replacememnt bill?

 

[VicS]

I guess that housing unscrews. That might be difficult or it might not be.

Might be worth seeking advice on the Mercury/Mariner board at http://forums.iboats.com/forumdisplay.php?f=4

Look at it closely to be sure thats where the oil is coming from. Note which way round the seals are fitted.

 

[xeitosaphil]

Thanks Vic,

For all your help and relative links , have joined said site and await some replies.

Will let you know how I get on

regards Philip

 

[Joe]

Hi Philip
Outboard water pump impellers should be changed if you are using the engine at least every 2 years to be on the safe side
4 years is too long to leave it really
They are made of rubber and all sorts of things can happen to them over this time squashed up in a water pump housing.
Too much to go into detail here.
They also drop in performance due to the arms becoming misformed. This is because of the shape of the water pump housing which bends them into a shape while in periods of long non use.
My advice is to change it and you will see a marked improvement to cooling.
Before you start to strip anything check the gear oil for water or the oil being a milky colour.
If there is water in the gear oil then you may well ned to re seal the gearbox.
If not and the oil is good not milky in colour then it may well just be unburnt oil leaking from the exhast hub.
You wont really know till you check the oil.
If its the oil seals then you may well be better of getting an outboard specialist to do them as they often need special tools to do them.
Unless ofc you are happy to tackle it your self with a good owners manual with a description of how to do it.
Hope this helps
Joe

 

[xeitosaphil]

Hi Joe,

Thanks for the info, have taken conserns onboard and will probably do it anyway, However not really sure how cooling can improve ? as it is working perfectly at the momen,( if it lasts that is)

Do they go all of a sudden or does the flow reduce over a period of time?

The thing that does consern me is the oil leak

Would do the oil seal myself as I have Mercury outboard workshop manual on the boat, just not sure if the hub and drive shaft assembly requires specialist tools to remove it or can the hub just be unscrewed?

Once I find this out I can proceed

Thanks anyway Philip