Impellers

[justchange]

I've seen here and read to NOT run the engine without a water supply. Not even for 5 second according to the manual I have.


I'm really wondering about this. AFter I bought my boat, I ran it for a total of about 5 minutes without water. While this wasn't continuous, according to the manual, the impeller should have been junk. I changed it along with the housing as I felt it had a problem. What I found was a housing that had damage to the inner part where the impeller "blades" actually run.[I think it'd been frozen] The impeller itself showed no signs of damage. In fact it looked as good as the new one except it was already bent in the correct direction.


So, after this experience, I have to wonder about this.



What have your experiences been with impellers?

 

[Apollo75]

Re: Impellers

I was just told a long time ago not to run the engine without water to the impeller. Never have yet ---> they still don't last long.

Turn the hose on


OFM

 

[Blujay96]

Re: Impellers

The bad thing about impellers is they are hard to tell if they are bad by looking at them. If you think about how fast you motor is turning and depending on the gear ratio of the drive even at idle your impeller could be turning at 500 to 700 times every minute. At that speed you can heat up the rubber and harden it and though the impeller may look good it will never work at the same capacity.

 

[ziggy]

Re: Impellers

this is a good read..

http://www.boatfix.com/merc/Bullet/87/87_14.pdf

personally, i replace mine yearly.

if you've ever had an overheat, you'll be real careful. overheats are preventable. all the associated parts that get melted is the big bummer.....

never run w/o water applied...

 

[Fishermark]

Re: Impellers

The impeller itself showed no signs of damage. In fact it looked as good as the new one except it was already bent in the correct direction.

"Already bent in the correct direction." In other words, it has already taken a "set". That alone shows it is past time to change. You also don't mention what outdrive you have. It is my understanding that some have a little more tolerance than others for running dry. Bottom line, it is never a good idea.

 

[justchange]

Re: Impellers

"Already bent in the correct direction." In other words, it has already taken a "set". That alone shows it is past time to change. You also don't mention what outdrive you have. It is my understanding that some have a little more tolerance than others for running dry. Bottom line, it is never a good idea.

The drive is an OMC Stringer from 1976. I felt that the impeller should be replaced as it didn't seem to flow water as well as I'd like. The rubber in the old impeller felt the same as the new one. The previous owner didn't do that great of work on it. An example is the use of red Permatex instead of the recomended #2 Permatex.

I'm currently waiting to replace the shiftwire as it showed problems. Other than that, I had to replace the front engine mount and transom seal.

Oh well, it's something else to work on.

 

[renny1]

Re: Impellers

wish i`d taken a pic of my new impellor and housing to show you what happens if you dont use water..the housing had even melted so pls pls always use water

 

[T-Bone Coug]

Re: Impellers

The moron who owned my boat before me ran it without water in his driveway for several minutes when he was showing it before I came along. I discovered this when he offered for me to hear it run, claiming that it didn't need muffs because of the coolant reservoir. I ended up buying it for about $1000 less than he thought it was worth because of the "cosmetic" issues, but it definitely wasn't pumping enough water.

I went ahead and ordereded the entire pump just for good measure because the nearest parts supply is an hour and a half drive. Upon disassembly, the impeller didn't look bad, other than one "leg" in the wrong direction. BUT: legs already bent means hardened rubber. Try to bend the legs on the new and they snap back to initial position. Hardened rubber means too much heat (too hot for short time, or normal heat for long time) so it's bad.

When I inspected the lower and upper casings they appeared good at first glance also. But looking closely around the edges where the gaskets seal the plastic had melted. Only slightly, but enough not to trust the old housings. So inspect it very carefully before assuming it's okay.

 

[justchange]

Re: Impellers

When I ordered the impeller, I ordered the houseing an everything. Replaced all of it too. The place I kind of messed up was not geting the impeller key. The one that as in there was very sloppy. Before I put it back together, I'm going to take this back apart and replace that key.

 

[scutly]

Re: Impellers

The moron who owned my boat before me ran it without water in his driveway for several minutes when he was showing it before I came along. I discovered this when he offered for me to hear it run, claiming that it didn't need muffs because of the coolant reservoir.

Holy crap the same thing happened to me but i didnt know any better and almost overheated the third day out. ended up getting the whole quicksilver pump kit for good measure rather than saving a few bucks on aftermarket. now i will just change out impeller every year.

 

[justchange]

Re: Impellers

I found this. Found it interesting not to mention overdue.



http://www.globecomposite.com/pages/products_impeller

 

[renny1]

Re: Impellers

looks good but geez would i still risk it....i doubt very much

 

[Bondo]

Re: Impellers

not to mention overdue.

Ayuh,... They've been around for Years,.... Just alittle hard to find...

 

[frank246]

Re: Impellers

What is the difference compare to the jabsco pumps that are mounted above the waterline and run dry while sucking up every time the engine gets started.