Yamaha 2hp 2 stroke how to dismantle?

[Katouf]

I've got a water pump problem with an old (1984?) but little-used outboard that came with Katouf. It starts and runs but now no water comes from the exhaust. It is regularly run in the after-use fresh water tank at the club so salt deposits shouldn't be a problem.
I've followed the threads on the MB forum and am confident that the impellor has died of old age. The problem is how to get at it!
I've undone the two bolts and got the lower casing apart but only about 1/4". I'm reluctant to pull or lever too much (to try and pull the drive shaft from the head or the cooling water tube from its rubber grommet) in case they won't go back.
Thought I'd try going in from the prop end to release the circlip at the bottom of the drive shaft but having undone the top and bottom 10mm bolts, I can't separate the packing gland from the housing - the paint is still new and the joint is well hidden. It's remained undisturbed and unserviced for years.
Should I hit it, lever it apart or what? I've looked at the boats.net/parts website for the exploded drawings (thank you Vic S) but cant see anything obvious. I need to be careful as the part is labelled obsolete! Any ideas?

Alan

 

[captainboo]

Unfortuately you are in a bit of a catch 22 situation. I had exactly the same problem with a 4hp yamaha. The shaft would not pull out of the crank due to seizure and removing the circlip at bottom dosen't help as the pump impellor has a roll pin through the middle and a cover bolted over the top. You cannot remove the lower casing from the leg without removing the shaft from the crankcase first.

I gave up being gentle on mine and eventually destroyed the lower casing/water pump trying to get it apart! The circlip on the end of the shaft broke and the rollpin ripped out through the pump housing. The shaft is still stuck in the engine even after gripping in a vice and belting the lower part of the crank with a lump hammer!

Result - bought another second hand engine!

You could try squirting a penetrating spray through the gap so it runs down the shaft to the joint between it and the crank but other than that it is brute force and hope it gives before it breaks.

P.S. I have got the Full Repair Manual supposedly for all Yamaha outboards 1984-1996 2-250hp. If you pm me I can email you the manuals that should cover something that resembles your engine!

P.P.S. Don't be surprised if you do get it apart and find serious corrosion. The packing gland on the engine I broke was corroded away and the bottom bearing seal housing on the shaft was also just white powder!

 

[pete]

I had the same problem with my Yam 4 hp 2 stroke, after a fair bit of hammering down on the cavitation plate (protected with a piece of wood) and inserting wedges in the joint I eventually got the shaft out but not before breaking a bit off the cavitation plate. on further inspection the splined hole in the crank shaft was full of white/grey crud which took a poking out. I greased the splines with silicone grease put it all back together and it is still going strong and although the cavitation plate has a piece missing I cannot tell any difference.
Pete

 

[Lakesailor]

Woah!
Does this motor have gears or neutral?
If not the impellor will probably be behind the prop.
This diagram from the Tohatsu (same motor)

If it's not the impellor it could be blocked water passages around the cylinder block, particularly the transfer hole between the block and the head. A bit more involved but not too difficult. Please don't use silicone gasket goo instead of new gaskets. I've just solved a non-pumping Evinrude in which the gasket goo had blocked the water passage!

 

[pagoda]

I've got a water pump problem with an old (1984?) but little-used outboard that came with Katouf. It starts and runs but now no water comes from the exhaust. It is regularly run in the after-use fresh water tank at the club so salt deposits shouldn't be a problem.
I've followed the threads on the MB forum and am confident that the impellor has died of old age. The problem is how to get at it!
I've undone the two bolts and got the lower casing apart but only about 1/4". I'm reluctant to pull or lever too much (to try and pull the drive shaft from the head or the cooling water tube from its rubber grommet) in case they won't go back.
Thought I'd try going in from the prop end to release the circlip at the bottom of the drive shaft but having undone the top and bottom 10mm bolts, I can't separate the packing gland from the housing - the paint is still new and the joint is well hidden. It's remained undisturbed and unserviced for years.
Should I hit it, lever it apart or what? I've looked at the boats.net/parts website for the exploded drawings (thank you Vic S) but cant see anything obvious. I need to be careful as the part is labelled obsolete! Any ideas?

Alan

My ancient (pre-cdi -no gears) 2hp Yamaha was badly salted up when I recued it from my father's shed. In the process of stripping it down to dig the salt / corrosion out of the water passages in the head and exhaust manifold- I had to dismantle the leg.
The grommets at the ends of the water tube had gone hard- and it pulled the whole lot from the underneath of the power head / manifold. It ought to have come out reasonably easily.
It is a rather fiddly job putting the water pump back together and making sure the water tube is in the right place both ends. New water tube / seals each end, new impeller & pin etc.
Much better now.
If you have problems with old Yamaha parts, I have found Caley Marina at Inverness both knowledgable and helpfull, and they post stuff quite readily.

Graeme

 

[mcanderson]

iBoats

Have a look at iBoats.com They have a wealth of info and if you can't find a helpfull post searching, then post your own and someone will come along.

 

[claudio]

I have had a lot of success for outboard parts, particularly for Yamaha parts from www.boats.net

They carry a lot of stock and despatch efficiently.
You can also see exploded diagrams and parts lists even if you don't buy from them.

Just a satisfied customer,

 

[Katouf]

Sorry for the delay in getting back on the forum and thanks for the replies.

The outboard is the non gear/astern model - once started you go where you're pointed. The water pump is definitely not behind the prop.

I'm still hoping that a treatment with plus-gas dripped down the upside down drive shaft (accessed through the gap already opened out between the lower casing and the leg) will free the drive shaft from the head.

Not a priority at the moment as SWMBO has some urgent gardening and decorating jobs in exchange for sailing last Friday and yesterday!