water impellor direction
 

-I changed my water impellor today on my 150 mercury o.b. 1988, im not 100 percent sure its in the right direction, I started it and it pissed out good my question is this, if its in wrong how would you know? the ribs facing the wrong direction, how would you know, thanks

don't worry, once you fire it up, it will flip them the correct direction, the large diameter water pumps can stay the wrong direction, but the small diameter mercs tend to flip in the correct direction

Not to hijack this thread, but I still wonder WHY we have these flexable impellers that we need to change all the time. (Aside from the obvious expense that equals profits for the makers).
I have 2 British Seagull outboard motors... both of them have solid impellers like those found in a pedestal sump pump. They work perfectly. So why do we put up with these rubber impellers? My pedestal pump has a 3/4 hp motor on it and it pumps to a 25 foot head. And thinking about it, a regular car water pump also has a solid impeller, and they do just fine circulating the water around the engine. So WHY do we have rubber impellers?????

Probably the same reason we don't have permanent light bulbs. :head:

Did you know there's a light bulb that has been burning almost continiously since 1901 in a firehouse? It's in Livermore, Ohio and has been the subject of several researches, investigations, and documentations. It started out as a 60 watt bulb and now burns as a low (4) wattage bulb. It doesn't give out much light, but even still... 110 plus years......
(And I have a 6v high intensity night light on my night table that I put a 12v automobile bulb in...that bulb has been on continiously for the 27 years we've been living in the house. It's not a lot of light, but works just great as a night light). Obviously the trick to long life for a lightbulb is the burn it at a lower wattage than it was designed for.)

That's pretty cool. My point was there would be lots of lost revenue in the aftermarket parts industry if we had impellers that lasted for the life of the engine. Seems like everything these days is made to wear out after a certain amount of time. I don't think it is a coincidence and in a lot of cases I don't think it is just because it would be cost prohibitive to make stuff more durable.

Rubber impellers are used because the yare self priming by nature, and are forgiving to debris going through them like sand, and provide good output at low RPM's. There are other optons, but the rubber impeller is still the best overall option for reliability, longevity, and durability.

I'm still musing over the fact that Destroyer still sleeps with a night light:you:

Ya,.. I got tired of stubbing my toes against various items in the dark.. The glow of a little light works just great. Beside, it lets me see other "business" in the dark. :hide:

Ferm, I know that you know your stuff, and everything you said it true,
but just for the sake of arguement, let me put forth the following. Both of my Seagulls pump a ton of water when they run. One is a 2 1/2hp and the other is a 4hp. Both have solid impellers similar to the kind found on just about any pedestal sump pump. I have a pedestal sump pump, and looking at it I find I was wrong, it's a 1/2hp motor, not the 3/4 I thought it was. Regardless, it still pumps to a 25 foot head. At 3 feet of head it will pump about 4000 gph. According to it's specs, it's designed to pass up to 3/8" solid debris, which is far more than any rubber impeller will.
You say that rubber impellers are self priming by nature, but if submerged, so is a pedestal pump. You would probably have to redesign the lower unit a little to get the pump impeller under the water intake ports, but other than that the self priming feature is pretty much a wash.
As stated above, the solid impeller will pass debris like sand and seaweed about the same as a rubber unit... perhaps a little better. Finally, my pedestal pump impeller is direct coupled to the motor via a shaft, turns at 1725 rpms and pumps 4400gph at zero head. That's a lot of cooling water at idle speed.

I know that this is all just conjecture, but it would seem to me that there's really no good reason to not use a solid impeller, especially given the fact that the British Seagull engines, (considered by many to be the best, most reliable small outboard engine ever built), use a solid impeller in their design. Really, I cannot see why they could not be used on larger engines. I wish some engineer could give me some hard facts documentation as to why the rubber impellers are used. (Other than the fact that it's just good business to make a unit that needs yearly replacement at about $35 per unit)... Multiply that by how many hundreds of thousands of outboards in use and that's really big business.