Impeller question

[dawson515]

I just bought a boat and it was overheating so I looked at the impeller and noticed that it was crammed insides the impeller liner. Is the impeller suppose to be touching the liner?

 

[Gary H NC]

Re: Impeller question

Yes,and the fins of the impeller should be flexible with no dry rot type cracks or missing pieces.

 

[Newbie@boats]

Re: Impeller question

Might be the water pump in the motor if the impeller is in good condition.

 

[dawson515]

Re: Impeller question

I was told that the boat was running hot at idle, it got up to 180 degrees while i had the ear muffs on it. I am going to check the thermostat next and then see about replacing the water pump. The impeller was so tight in the liner that I thought maybe someone put the wrong size impeller on it.

 

[Bondo]

Re: Impeller question

Might be the water pump in the motor if the impeller is in good condition.

Ayuh,... Highly unlikely, unless he's got a 470 like your's...
Which brings up the Question for Dawson,...
What are We workin' on Anyways,..??

 

[dawson515]

Re: Impeller question

89 VIP VISION with a 2.3 OMC Cobra ford motor.

 

[dawson515]

Re: Impeller question

I guess my question is, can an impeller that is too big cause water flow problems?

 

[cr2k]

Re: Impeller question

The impeller is supposed to be touching the inside of the housing. It pumps by compressing to pump and expanding to suck in water (it is on a concentric). If the vanes are set in a folded position and stiff it needs to be replaced. If any vanes are missing they MUST be recovered form your system or you will have problems from then on. The "water pump" on the front of the engine (called a circulation pump) usually never needs replacing and has little to do with water getting to the engine as this is the job of the impeller, it merely circulates the water through the engine.
If run dry (no water muffs on outdrive when out of water) it will destroy the impeller and the housing in a matter of 15 seconds or less. This can lead to overheating also as well as costly replacement of the housing.

Usually when overheating at idle and running normal at speed it is a sign of a weak impeller and time to change it. A Cobra drive is the easiest of all to change. Look above in the Stickys for the correct manual for your drive to find out how to do it.

 

[dawson515]

Re: Impeller question

The impeller is in excellent condition but the problem is that when it is inside the liner it is bent down so much that the tips of the impeller blads are all touhing each other. I understand that they need to be making contact with the liner but there is hardly enough room for any water to get between the blades of the impeller because it is such a tight fit.

 

[Don S]

Re: Impeller question

Those blades bending over is what makes it a pump that creates suction, and pressure. That is how it's supposed to be.

 

[dawson515]

Re: Impeller question

Ok, well I will replace the impeller anyways because it needs to be done often.