Yamaha 2hp outboard/impeller change

[castaway]

I think that the impeller is knackered, or at least there is'nt any water coming out of the tell tale.

I have always been careful with flushing the engine thro so hope the water cooling galleries are still in good shape..so thought i would remove the bottom of the leg and check out the impeller..

Only thing is that after taking out the 2 bolts the leg end does'nt want to come free. I've been tapping with a plastic hammer but am a bit reluctant to use any force.

Any one removed one of these before?

Thanks Nick

 

[richardabeattie]

Questions:
Did it suddenly stop squirting whie running (impeller gone) or did it fail to squirt after a period of storage (bunged up)?
Have you tried poking wire into the water intake and outlet?

 

[captainforbes]

Yea I know it well. The book says something like "slacken nuts A&B then gently remove the lower leg. The first time I did it it took a week of ever increasing force, finishing up with breaking the lower casting. Luckily I got a secondhand casting from an outboard graveyard.
IMHO the first thing you shoud do with any new o/b is to remove the lower leg and use seacock grease to coat the bolts before replacing them. This way, it will come apart when you need it to.
I'm afraid force and heat is the only way to remove it. Having said that, the other cause of the lack of water is blocked water channels in the power head. Cleaning them means removing probably the cylinder head to get acess to the water channels. using pipe cleaners to clean the passages. A simpler method would be to remove the prop and immerse the intake ports in a container (bin?) and fill with ewater to the intake ports. Dissolve car radiator cleaner or possibly kettle lime scale cleaner and run the engine. Hopefully it slowly runs clear.
Got any advice on how to clean teak decks?!

 

[VicS]

[ QUOTE ]
Dissolve car radiator cleaner or possibly kettle lime scale cleaner and run the engine

[/ QUOTE ] Car radiator cleaner probably not likely to be any good, an acid based kettle descaler probably better or an acid based central heating boiler descaler. As a last resort hydrochloric acid (brick cleaner)

The trouble is that if the water passages are completely blocked you can't get a descaling solution through them so you are stymied.

I take it the leg does have to come off. Some small outboards with a fixed drive (ie no clutch) have the impellor located behind the prop rather than on top of the gear box.

 

[castaway]

Well that is a good point...re the impeller location. The only time I have done this before was on a Johnson 6hp and it was between the leg and the g/box.

One reason for suspecting the impeller rather than the water passages is that when I tried to start it after the winter the whole engine was very 'stiff'..not tight piston in bore type stiff..more the sort of tightness one would get from an out of shape impeller, cleared after a while of running in a tub but no tell tail after that.

Thanks Nick

 

[VicS]

[ QUOTE ]
The only time I have done this before was on a Johnson 6hp and it was between the leg and the g/box.

[/ QUOTE ] That has got f,n & r gears so the pump must be driven by the drive shaft or it will get no cooling water when in neutral. In the little ones with a fixed drive the pump can be on the prop shaft because it is always turning. IIRC the little Johnyrudes are like that but i do not know about the Yammies

The iboats forums are an excellent place for help with outboards

 

[castaway]

I've got the foot off now..impeller is in the usual place, however problem continues with the shaft from the power head down to the gearbox is joined just above the impeller.......in somewhere amongst the rust and corrosion should be a pin 8uggered if I can find it...of course the impeller will not go over the shoulder and up the shaft and next course of action is to strip the little g/box and see if I can do it from the other end.

First I will see if I can get some crack detector fluid from work see if I can find the pin.

Thanks Nick

 

[richardabeattie]

Face it laddie ye'r just fair doomed and it's time to smack open the piggy bank.

 

[vidapura]

HEllo,
Could you please tell me if you ever figured out how to get the impeller out?
I'm stuck where you were with the water pump housing lifting so far.. but won't go up the shaft...
And can't figure out how to open the gearbox... opened the bolts but its like its glued together..
Is that where you release the driveshaft anyway? Or should I leave the gearbox alone?

Yamaha 2hp 2b

Thanks
Vida

I've got the foot off now..impeller is in the usual place, however problem continues with the shaft from the power head down to the gearbox is joined just above the impeller.......in somewhere amongst the rust and corrosion should be a pin 8uggered if I can find it...of course the impeller will not go over the shoulder and up the shaft and next course of action is to strip the little g/box and see if I can do it from the other end.

First I will see if I can get some crack detector fluid from work see if I can find the pin.

Thanks Nick

 

[alahol2]

Here you go... http://www.troppo.co.uk/odds/Mariner%202M%20Impeller%20replacement.pdf

 

[Seajet]

I have one of these superb little engines, I have found it necessary to take the head off and clear the galleries every couple of years; unless you've been running it dry not in water, I'd bet it's salt build up rather than the impeller.

 

[vidapura]

Oh you absolute Gent!!
Thanks very much! That really explains it now!

I knew there had to be something holding the shaft in there..

Brilliant.

Thanks

Here you go... http://www.troppo.co.uk/odds/Mariner%202M%20Impeller%20replacement.pdf

 

[vidapura]

I have one of these superb little engines, I have found it necessary to take the head off and clear the galleries every couple of years; unless you've been running it dry not in water, I'd bet it's salt build up rather than the impeller.

You're dead right actually...
When I couldn't get the impeller out I opened all the bolts on the underside to release the complete leg from the powerhead
And I saw a lot of gunk in the various channels. (as you predicted)
Cleaned that out and reassembled everything.
Ran the engine again just to see if it had helped and lo and behold the telltales were squirting out water like mad.

But I have some questions..

(1) getting the foot back on was torturous.. trying to locate not only the driveshaft but that pipe that goes into the waterpump.. jumpin jesus that was a right pain.. basically had to be an octopus to hold it all together and the try squeeze the whole lot closed by tightening the two bolts.. If there is an easier technique I'm all ears.

(2) I only opened the bolts visible on the underside of the main housing (6 bolts ) underside of the powerhead.. so I was able to clean the channels shown in that pdf.. but I didn't open anything above that .. so I'm not sure if the channels inside the powerhead need cleaning out as well? If so.. how to do that ?

I basically couldn't get the screws out of the case to take the plastic off.. so I left it for now..
But if I really need to get in there I'll go back and try it.

I'm thrilled to have the info about how to get the impeller out now.. I know its working.. but its an old engine and I think it would be no harm to put a fresh one in there.. especially since I didn't come across a single gasket or seal during the entire disassembly.. heh...

I was thinking I'd put some limescale remover into the water in the tank I use for running the engine when I get home each time.
Any thoughts?

 

[mr_average]

As some of you seem to have had some success here I'm going to jump onto this thread. I still can't get the lower leg off a Yammie 2b. When I remove the 2 bolts it comes loose but only drops about 1 or 2mm. I took the circlip off in the gearbox (under advice from my spare parts supplier) - it broke and now parts of it are missing, presumably behind the gear - but the small gear is still on the shaft. As I try and remove the lower leg should the drive shaft come away from the head? Do I need to release something up there first? It certainly feels like there's something else to be undone, rather than the gunk of ages holding it all back.

 

[VicS]

As some of you seem to have had some success here I'm going to jump onto this thread. I still can't get the lower leg off a Yammie 2b. When I remove the 2 bolts it comes loose but only drops about 1 or 2mm. I took the circlip off in the gearbox (under advice from my spare parts supplier) - it broke and now parts of it are missing, presumably behind the gear - but the small gear is still on the shaft. As I try and remove the lower leg should the drive shaft come away from the head? Do I need to release something up there first? It certainly feels like there's something else to be undone, rather than the gunk of ages holding it all back.

No I think the water pump will prevent it coming apart if you just remove the circlip. The impeller is pinned to the driveshaft and the pump casing is bolted to the top of the gearbox however I think on that engine you do
have to remove the clip and unbolt the pump from the gearbox and lift it off complete with shaft once separated from the leg so your efforts to remove the clip are not wasted. With others you can simply slide the pump up the shaft

Your trouble is probably that the drive shaft is rusted it to the crankshaft. Maybe turn it upside down an try to get some release oil to run down the shaft. Otherwise brute force and ignorance and hope it comes free before anything breaks.

 

[Gin]

I've got the foot off now..impeller is in the usual place, however problem continues with the shaft from the power head down to the gearbox is joined just above the impeller.......in somewhere amongst the rust and corrosion should be a pin 8uggered if I can find it...of course the impeller will not go over the shoulder and up the shaft and next course of action is to strip the little g/box and see if I can do it from the other end.
Reply
I have just acquired one of these little engines, as you may have seen elsewhere on here, and I too have had to change the impeller as a vane had broken off and disappeared. Dismantled leg from power head and gearbox/impeller casing from lower section of leg- no sign of it anywhere and waterways through leg and power head let water run through freely under just garden hose pipe pressure. Note- the emission of water when running with the broken impeller was less than impressive, just a modest but firm and steady spray, so I was hopin that a new impeller would improve things- it has not and I cannot risk removing the little black cowling/ deflector on the upper power leg where the water is ejected to see if there is any obstruction as a previous owner has mashed the machine screw head and it will be a b***er to remove without damaging the leg.
Anyway, back to the impeller change- a simple task which took all day yesterday due to complications peculiar to my unit.

1. The outer tube housing the drive shaft is lightly crimped to a square section near the bottom end, so it cannot be withdrawn from the tube without dismantling the gearbox which is an easy job. Remove prop, take care to remove shear pin and store it as it is a loose fit in the prop shaft.
2. Remove circlip from the projecting drive shaft end which retains the pinion wheel. Remove pinion wheel and note that there are two washers of different thicknesses which should be reassembled in the same order.
3. Now the lower leg can be removed from the drive shaft/tube together with the water pump and spacer plate to enable the impeller to slip off the pinion end of the drive shaft. Note- the tiny shear pin style peg which engages in the impeller slot is like the shear pin a loose fit and will fall out if you don' t take care.
4. Once the impeller has been changed then reassembly is the reverse of the above
So why did it take all day?
Probably me learning as I went along but I found that trying to get the 6 shouldered pinion drive shaft end back through the pinion wheel a very frustrating job as it simply wouldn't locate and the tiniest movement of the crown wheel aggravated matters. Nevertheless it is straightforward

I forgot to say that a good bit of the day was taken up through the actions once again of a previous owner who had clearly either lost a bolt or stripped the thread of one of the two locating points for securing the water pump housing to the lower leg and had dealt with that by installing a self tapper, which had then sheared off leaving a small ragged stud which was very very difficult to drill out even with a pillar drill. The result is not pretty but it is now secured by two screws as intended by Yamaha.

The water flow issue was no different after installing the new impeller but after running the engine for 5 minutes or so at high revs the emitted water never got very hot so I am thinking that all is OK. A YouTube video of another of these engines running has clearly got a better flow than mine but we shall see how it goes out on the river this weekend.

Hope this helps


First I will see if I can get some crack detector fluid from work see if I can find the pin.

Thanks Nick

 

[mr_average]

Thanks for the replies. There does seem to be more to this than some of the 'how to' guides admit - including the one on the PBO website. If I can retrieve the broken bits of circlip from the gearbox I may abandon the attempts to get at the impeller- it was for maintenance and inspection rather than a known problem.

 

[vidapura]

As some of you seem to have had some success here I'm going to jump onto this thread. I still can't get the lower leg off a Yammie 2b. When I remove the 2 bolts it comes loose but only drops about 1 or 2mm. I took the circlip off in the gearbox (under advice from my spare parts supplier) - it broke and now parts of it are missing, presumably behind the gear - but the small gear is still on the shaft. As I try and remove the lower leg should the drive shaft come away from the head? Do I need to release something up there first? It certainly feels like there's something else to be undone, rather than the gunk of ages holding it all back.

Ehhmm.. just on the drive shaft coming away from the head.. Yes it should.

(maybe download the pdf that is linked earlier in this thread.. with all the handy photos??)

When I got the two bolts off the foot .. it came down a few mils from the (blue) leg.. but didn't fully release...

I had to pull it away from the leg, but don't worry you are not breaking anything...here"s why:

Inside the leg are two things (1) is the driveshaft that brings drive from the engine down the leg into the gearbox..
but there is ALSO (2) a pipe.. its for rising the water pumped from the waterpump up into the engine head.

THAT pipe was still holding the foot to the leg in the absence of the two screws..

Its only held into the water pump by a small black rubber gasket.. you have to carefully pull the pipe out of that gasket in the water pump to get the foot and the driveshaft out of the leg.

Up in the head that pipe is held in the head by being bent at right angles and a flange holds it into the body of the head...
(you'll see this if you undo the six bolts on the underside of the head.

So, basically you can separate the foot , complete with drive shaft, from the head by pulling it down away from the leg, thereby extracting that riser pipe from the water pump...

Is that any help?

It might give you a better chance to get the drive shaft out of the gearbox as VicS suggests..
Cos if you've got the circlip off the shaft then the drive shaft should come up out of the gearbox having shed the "small gear" you mentioned.
Possibly if the circlip broke then a bit of it might still be in the way.. the small gear should come off the shaft and allow you to pull the shaft up out of the foot...
Otherwise there is no way to get the new impeller on the shaft.
Freeing the shaft at the top end is no advantage to you cos the waterpump will not slide up ..


PJ

 

[steve66]

Ehhmm.. just on the drive shaft coming away from the head.. Yes it should.

(maybe download the pdf that is linked earlier in this thread.. with all the handy photos??)

When I got the two bolts off the foot .. it came down a few mils from the (blue) leg.. but didn't fully release...

I had to pull it away from the leg, but don't worry you are not breaking anything...here"s why:

Inside the leg are two things (1) is the driveshaft that brings drive from the engine down the leg into the gearbox..
but there is ALSO (2) a pipe.. its for rising the water pumped from the waterpump up into the engine head.

THAT pipe was still holding the foot to the leg in the absence of the two screws..

Its only held into the water pump by a small black rubber gasket.. you have to carefully pull the pipe out of that gasket in the water pump to get the foot and the driveshaft out of the leg.

Up in the head that pipe is held in the head by being bent at right angles and a flange holds it into the body of the head...
(you'll see this if you undo the six bolts on the underside of the head.

So, basically you can separate the foot , complete with drive shaft, from the head by pulling it down away from the leg, thereby extracting that riser pipe from the water pump...

Is that any help?

It might give you a better chance to get the drive shaft out of the gearbox as VicS suggests..
Cos if you've got the circlip off the shaft then the drive shaft should come up out of the gearbox having shed the "small gear" you mentioned.
Possibly if the circlip broke then a bit of it might still be in the way.. the small gear should come off the shaft and allow you to pull the shaft up out of the foot...
Otherwise there is no way to get the new impeller on the shaft.
Freeing the shaft at the top end is no advantage to you cos the waterpump will not slide up ..


PJ

Common problem with these engines. The driveshaft tube fits outside of the driveshaft did into the impeller housing. It often sizes where the tube meets the housing. If all else fails strip it from the top down instead of bottom up. The tube locates into the exhaust plate under the engine block. Unbolt the engine and try to free it from the exhaust plate. Otherwise cut the driveshaft tube

 

[vidapura]

Thanks for the replies. There does seem to be more to this than some of the 'how to' guides admit - including the one on the PBO website. If I can retrieve the broken bits of circlip from the gearbox I may abandon the attempts to get at the impeller- it was for maintenance and inspection rather than a known problem.

I'd say its the broken bits of circlip that are preventing you getting the driveshaft out.
That small gear on the driveshaft has to slide off... its supposed to slide off when the circlip is removed..

Don't abandon it.. you're almost there ...
You'll have to get it eventually.. what will you do when the impeller finally wears out otherwise?
Seriously.. its one of those things that is a bit nerve-wracking the first time you do it.. but once you've done it once you'll be very happy you did.

You can get the impeller and manual on ebay as a package... just search for "yamaha 2hp impeller".. the manual and the guide posted earlier in this thread make it all a bit clearer...

And, by-the-by, if the impeller IS ok for now you should really separate the head from the leg (six bolts up under the engine) and clear the water passages (as suggested by castaway earlier in this thread) cos even if the impeller is ok it will be useless if the passageways aren't clear.
The guide posted earlier alahol2 is really helpful.. http://www.troppo.co.uk/odds/Mariner...eplacement.pdf

When I did all this my impeller was perfect but the water wasn't pumping until I cleaned the passageways.