Is It The Impeller

[bigmike35]

bet im pissing everyone off with this engine!
just had engine started after 5 years put flush muffs on before firing up noted no jets of water from pee pipe could the impeller be the problem or is there anything else i should check when changing impeller just orderd manual so going to have a go at it,what is the impeller made of ? i heard that if you cover with vasalene the impeller will suck up the vaselene to give impeller a longer life is this right?

[Tim M]

Chances are that it is the impellor that's casuing your problem; after five years its probably perished and isn't pumping water properly. Of course it may be something else like a blockage; check that a family of insects hasn't set up home in your water intake or in the tell tale pipe!

The impellor is made of rubber. I'm not sure about vasallene making it last long I think this might just make it easier to fit but someone who knows for sure wil be able to confirm that either way for you.
As far as changing the impellor goes it's really easy to and and doesn't cost a fortune! Will probably take you 20 minutes/half an hour and you just need a good set of spanners!

[Nasher]

Mike

as Tim said its probably the impellor, but its worth also considering:-

A blocked intake as Tim said.
Sometimes the plastic grill thats fitted over the intake can be clogged if the boats been left afloat with the engine down.

I had a 55HP Suzuki, that when I first had it used to get its tell-tale outlet blocked with a limescale like substance. I used to carry a 6 inch piece of wire on board to poke up it. It stopped after a few trips out then went on for years OK with a new impellor each year.

Some engines, and I don't think this applies to yours, have the tell-tale pipe after the thermostat, so only 'pee' when warmed up.

But its most likely the impellor, and thats worth changing if you buy a new engine anyway. I change mine every year anyway, as I'm paranoid

Nasher.

[Tim M]

You could also try using your rib air pump to "blast" any minor blockage away. Works for me

[ADS]

As nasher says, a bit of wire prodded up the pisser should sort out any blockages, or compressed air. Had the same thing with a mates 35HP Johnson, managed to hoover up half the river bed and blocked the pipe running from the cooling to the outlet itself, took bit of wire and it was fine.
I would, however replace the impeller as a matter of course, and its more likely to be the impeller anyway.

Richard B has done a good thread here with photos on a Yamaha impeller change:

http://www.rib.net/forum/showthread....mpeller+change

Regards,

Alex

[dctucker]

Originally Posted by bigmike35

bet im pissing everyone off with this engine!
just had engine started after 5 years put flush muffs on before firing up noted no jets of water from pee pipe could the impeller be the problem or is there anything else i should check when changing impeller just orderd manual so going to have a go at it,what is the impeller made of ? i heard that if you cover with vasalene the impeller will suck up the vaselene to give impeller a longer life is this right?

My freshwater 1980 4 cyl 80 hp Merc also sat (indoors) for a number of years before I put it on my searider. I had the same problem of no pee stream when I first got the engine running. Turned out that the pee pipe was in fact blocked and I got a good stream once I cleared that. I ran the motor for probably 20-30 hours this summer on the old impeller with no problems. I really DO need to change it though!! Probably ought to change the plugs in the spring too

Never heard of the vaseline idea. Sounds like BS to me...

Take a look at the wires too, many of mine were rotting badly and needed to be rewired.

Great resource for older Merc info is the iBoats Merc forum

[Nos4r2]

Originally Posted by dctucker

Never heard of the vaseline idea. Sounds like BS to me...

A thin layer of grease (not vaseline) is used while installing the impeller.It makes it easier to seat the impeller housing.


I've had the same problem with limescale-like substance. Backflushing with a hose through the telltale works very well to clear it-but you do need to change your impeller mike, if it stops pumping water your engine will be an expensive lump of scrap if you don't notice it in time.There's no fancy overheat alarms on bluebands.