Impeller Melting Housing and seized to shaft

[aggiechris]

A few seasons ago, I was doing a routine replacement of the impeller to find that the fins were chewed up. No problem, I replaced the impeller like I had many times before and went to start it up out of the water with the muffs on. After about 20 minutes, the engine started to overheat. I pulled the lower unit down to find that the impeller housing was now melted and the impeller was seized to the shaft. I believed that I had maybe gotten the wrong sized impeller as I do remember it being very difficult to slide the housing over during installation. So I went and got a new housing and impeller and installed, much easier to slide housing over this time. Got to starting again outside of the water with muffs on and again, after about 20 minutes, it starts to overheat. I again pull down the lower unit to inspect and find that the housing has melted once again. I have flushed the system with a water hose and water is moving through the system clearly. I am at a loss at what to do. Any help would be appreciated.

 

[stonyloam]

Re: Impeller Melting Housing and seized to shaft

More info please. Year, drive & engine, serial numbers if you have them?

 

[Pikey23]

Re: Impeller Melting Housing and seized to shaft

is it possible that you missed putting the key back between the impeller and shaft?

 

[aggiechris]

Re: Impeller Melting Housing and seized to shaft

It's a 1978 Volvo penta 120 horsepower sterndrive

 

[aggiechris]

Re: Impeller Melting Housing and seized to shaft

And yes, I did make sure the key was inserted. The new impeller kit came with a new one.

 

[Don S]

Re: Impeller Melting Housing and seized to shaft

I pulled the lower unit down to find that the impeller housing was now melted and the impeller was seized to the shaft.

It's a 1978 Volvo penta 120 horsepower sterndrive

Uhhhhh, Volvo's have never had pumps in the outdrive. So what do you really have?

 

[aggiechris]

Re: Impeller Melting Housing and seized to shaft

Ha, don't know why I wrote that, was in that forum earlier. I am pretty certain what I have is a MerCruiser 120, haven't used the boat in a while and am about to start redoing the entire interior but want to make sure I can drive it before I put a lot of money into it. So, if memory serves me right, it is a mercruiser 120

 

[Don S]

Re: Impeller Melting Housing and seized to shaft

The lower pump housing is also plastic, and normally when the upper housing is warped from heat, so is the lower. With a warped or melted housing, it will suck air instead of water and continue to burn up new impellers.

 

[aggiechris]

Re: Impeller Melting Housing and seized to shaft

I am going to have to try that. I assumed the water pump kit that I purchased would have come with all of the parts necessary to replace the water pump. However, as I have been doing my research, not seeing the whole kit together. They sell them separate. Thanks for the advice.

 

[firepro86]

Re: Impeller Melting Housing and seized to shaft

Have you checked your cooling system for quagga or zebra muscles? Here in California more and more lakes are popping up with these destructive little buggers. They can get into your cooling system and clog everything up. They like to get into the lower end voids and take hold snd then it makes it impossible for the impeller to pick anything up from the outdrive then your impeller is just spinning creating heat and then it just comes apart. Just an idea.