Impeller Vs. Water Pump???

[jgliatta]

How do I know if I have to replace just the impeller or whole water pump? I saw three kits on the merury parts page. There was the Complete housing pump kit #3316 and the Upper pump housing kit #3517 and the Impeller repair kit #3217. Which do I need to replace? Is it difficult to do this?

 

[Jack Shellac]

Re: Impeller Vs. Water Pump???

It's not a hard job to do, but generally you have to go into it before you know whether you need just an impeller or the whole pump. If the motor is approaching, say 5 years old, I believe I'd order the pump kit. It's better to have too many parts than have to stop and wait for more. You'll need them sooner or later.

 

[jgliatta]

Re: Impeller Vs. Water Pump???

It is actually a newly rebuilt lower unit about 6-8 months old now. Is it possible it has a bad impeller or pump already?

 

[Jack Shellac]

Re: Impeller Vs. Water Pump???

You should't have to be doing it this soon, although it's possible that the impeller has failed. Either through sucking up sand or debris or just being a bad impeller. If you paid someone for the rebuild, I'd take it back to them.

 

[jgliatta]

Re: Impeller Vs. Water Pump???

It heats up and (pisses) the tell tale slowly when in reverse. Is this supposed to happen? Does this sound like the impeller or water pump?

 

[NathanY]

Re: Impeller Vs. Water Pump???

Do you know the exact temp of the water coming out? How hot is the powerhead? Could just be that the tell tale has something stuck in it.

 

[Boatist]

Re: Impeller Vs. Water Pump???

FishForever<br />What Brand and size motor are you talking about?? Is it a Outboard or I/O??<br /><br />Several thing could cause new impeller to go bad. One I see all the time is someone starts the motor up while up on the ramp to warm the motor up before launching. Problem with this is rubber impeller is sliding on metal water pump houseing and without cooling water the rubber heats up and melts. Two if get stuck on a sand bar and use motor to get off, it suck up the sand and sands the impeller and houseing. Three if some one changed the impeller and the houseing is bad, rough, pitted or cracked it will wear out new impeller. <br /><br />In general if none of the above thing have been done and motor is run in clean water then impeller should last at least 5 years and the houseing will be ok also. If you run in salt water and do not flush the engine then houseing can become pitted and cause problems. I change mine every 10 years and have never had a overheating problem but I check the water flow indicator after I start up and watch my heat guage. Having said that every other person will tell you to change every two years and your dealer will also.<br /><br />On a Outboard the impeller is the water pump. The kit normally contains the impeller and and the housing it runs in and the drive pin. Some Kits may also contain some seals.<br />Most I/O's have a impeller in outdrive then a water pump (circulation pump) in the engine. <br /><br />If you only have problems in reverse it could be exhaust gas out of prop is causeing water pump input to suck up exhaust gas instead of water. I would think for this to be a real problem would have to back up very hard for a long time.<br /><br />Good Luck and Welcome to the Board.

 

[jgliatta]

Re: Impeller Vs. Water Pump???

Hi Boat,<br />its a 225 hp mercury.<br />It only occurs in Neutral (extended period of time idling) or after being at idle for a while, then kicking it into reverse and backing down. It heats up much more rapidly this way because of the reduced stream. However, it runs perfectly cool when I hook the hose up to the flush connector. I am going to have the impeller changed and see if that solves the problem.