4hp Johnson Impeller - Can You Reverse and Reuse?

[Larrygs]

The impeller on my 1969 4hp johnson does not appear to be putting out a lot of water and the engine is very hot. I have a previous impleller (slightly worn) and it appears to me you could install it in reverse (Upside down) with the arms angled the correct way (opposite the way they were previously). Would that work? Thanks... Larry

 

[River Boy]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

No.

 

[samo_ott]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

Everyone will say no, but I have tried it on some engines and it has worked. But you have to be prepared to take the risk if the impeller fails. I was. But if you took it out originally wasn't there a problem then? Most folks don't have spares lying around. Also, if the quantity is low I find that usually the water pump housing might need changing also...

 

[Larrygs]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

Why not? Wouldn't the arms be tight against the sides and be turning the correct direction?

 

[Larrygs]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

Steve... Just saw your reply. I have not yet looked at the impeller now in the motor. The one I've got was replaced I guess and I just held on to it. What would be a sign if the impeller was to "fail" as you say? No water thrown out? Larry

 

[samo_ott]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

Yup. No water. Overheated head. If you're lucky it will start again once cooled. If you're unlucky and don't catch it fast enough you're power head will be fried and you'll be looking for a new power head. That's why you have to be prepared to take the risk.

 

[Larrygs]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

Steve... How much time does it take to overheat with no cooling? If I tried this should the water be coming out instantly so that I can shut it off quickly if I see no water? Thanks for your info and replies... Larry

 

[tashasdaddy]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

don't try it, they have a tendency to take the set, then when reversed they come apart, and can clogged the water passages. new impeller is cheap insurance.

 

[samo_ott]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

As I said, it's a risk. And I would not knowingly run an engine more than 30 seconds or so without cooling...

 

[F_R]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

don't try it, they have a tendency to take the set, then when reversed they come apart, and can clogged the water passages. new impeller is cheap insurance.

When you bend the blades back against the set-in curve, they often break off, causing instant overheating and possible clogging of the system.

Besides, that is not the problem. The blades only contact the outer rim of the housing at slow speeds anyway. At slow speeds, it acts as a displacement pump. At higher speeds, they flex back and act as a centrifugal pump.

 

[CATransplant]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

I guess I'm trying to figure out why anyone would even think about using an old impeller. They're not hard to buy, and not all that expensive. Once you have the lower unit off, replace the impeller with a nice new one. Don't try to save money on something like this. You'll end up costing yourself a heckuva lot more in the long run.

Just head for your nearest Evinrude dealer and you can have a new one right now. Or order one online and have it in a week.

 

[jtexas]

Re: 4hp Johnson Impeller - Can You Reverse and Reuse?

if you were, say on day 3 of a 4 day camping trip and had an impeller failure, and had one on hand that you had removed in serviceable condition, I'd say go ahead and put it in but *don't* reverse the vanes.

I have no scientific or documentary evidence to support my position, but I just imagine that if you bend a piece of rubber back and forth, it starts to crack.................