Where is the impeller on an Yamaha 6hp outboard?

[OGITD]

Hi all,

I’ve just had a lesson on the stability or rather not, on the life span/properties of modern unleaded petrol. It appears that it becomes almost unusable after just a few months. I did take the advice of a few more experienced fellows and changed the fuel for new stuff and also cleaned the jets and float chamber, it then started first pull every time.

The problem now is it does not appear to pump water, so my question is:
where is the impeller located on a Yamaha two stroke, twin cylinder outboard.

This as (call me overcautious and paranoid) I need to have a reliable auxiliary.

Thanking you all for any help/pointers (no I do not have the manual Frank).

 

[VicS]

On some small outboards with a fixed drive it is located behind the prop but I guess that does not describe yours so it will be on top of the gearbox driven by the vertical drive shaft.

If that is so you will have to separate the gearbox box from the leg.

reference to a workshop manual would be advisable

However if the engine is of any age or has not been flushed regularly with fresh water you are likely to find the water ways are clogged up.
You have checked that it is not just the telltale that is blocked i hope.

By the way there is no problem storing fuel from one year to the next provided it is stored properly. I always do. As a precaution I always filter it before use and usually mix it with an equal volume of fresh

 

[srp]

You may also want to check the thermostat - it might be blocked with salt crystals, the by-products of corroded aluminium or bits of broken impeller. On my Yamaha it was totally blocked - taking it out and throwing it away cured the problem.

 

[OGITD]

Thanks guys,

I’m not bad with mechanics so tomorrow I’ll be stripping it down, so far the list of checks are:
1 Impeller,
2 Thermostat,
3 Telltale and waterways.

Thanks again.

 

[William_H]

Just be extremely careful with bolts that arte tight to undo. The 6mm stainless steel bolts will snap of so easily. Use heat on the bolt head and plenty of antisieze fluid.
When you reassemble use lots of grease on the bolts or better still Duralac. If it is like my old Johnnson there is a pipe running from the pump to the motor head. I can attach a garden hose to the pipe and get a good flow through the engine. (tell tale and exhaust) This confirms free passages. The pump can loose efficiency because the housing and end plate are worn. There is total kit available for the Johnson so hopefully for yours. good luck olewill

 

[Topcat47]

Replaing the gearbox post refit can be a pain. It takes two if you're a bit clumsey like me. Don't forget the water pipe either. There's very little clearance and for some reason the Makers seem to think you've three hands each.

BTW the handbook was useless....if there is a simple technique for doing this it seems to be something of a trade secret.

 

[reeac]

[ QUOTE ]
Hi all,

I’ve just had a lesson on the stability or rather not, on the life span/properties of modern unleaded petrol. It appears that it becomes almost unusable after just a few months. I did take the advice of a few more experienced fellows and changed the fuel for new stuff and also cleaned the jets and float chamber, it then started first pull every time.

The problem now is it does not appear to pump water, so my question is:
where is the impeller located on a Yamaha two stroke, twin cylinder outboard.

This as (call me overcautious and paranoid) I need to have a reliable auxiliary.

Thanking you all for any help/pointers (no I do not have the manual Frank).

[/ QUOTE ]

Regarding your opening statement on modern unleaded I recently used last year's 50:1 mixture in my cheapskate Suzuki 2.2 and it started first pull and has done so on the several occasions that I've used it since. The mixture has been kept in its usual plastic "can" in the garage.

 

[impact30]

I had one of those (unknown year but very old) and the telltale got blocked every 3 weeks or so. The impellor was changed each year at first but then I just ran it for 4 years and it was fine. I flushed it with milking machine cleaner (liquid type) for about 10 minutes and it cleared all debris in waterways and no more bother. Engine was old so I wasn't too bothered but it was very reliable.

 

[OGITD]

Re: Where is the impeller on an Yamaha 6hp outboard? THANKS!

Thanks all,

Job done.

New impeller, four bolts above the gearbox, one locking bolt on the gear change rod and four bolts on the impeller housing. A little cleaning with some silicone grease for the rubber blades, reassembly, a 30 minute run in the test tank with a short blast around Troon harbour (I think I am now in trouble) and it works a dream.

I also discovered that it is the “C” variant due to the type of prop.

Thanks once again.

OGITD’s

 

[OGITD]

One last note.

One last thing, Yamaha also informed me that this engine is a detuned 8hp, just to add to the knowledge base.
Thanks again.