Replace your water pump!

[Glenn]

As a matter of practice, I replace my water pump impeller every 2 years like clockwork.  This year, when my mechanic took the pump assembly apart, he discovered "burns" and damage on the housing (see pics below).  

I had absolutely no inclination to think anything was wrong.  The pressure was 20-24psi....plenty strong.  There was no reason to believe there was an issue.

He said it probably happened when the water flow was temporarily disrupted somehow, and was allowed to run dry for a short period.  Mind you,  he said short!  He said it doesn't take much to cause damage like that.  

I asked what could have caused it, and he said it most likely caused when I ran over something like a plastic bag, candy wrapper, potato chip bag, big leaf or some other garbage floating in the lake....something large enough to cover the intake screen until it "blew" off.  He said from the time it happened until it cleared itself was so fast that I wouldn't have heard any alarms, and was just enough to cause the damage.

So, lesson learned... replace that impeller every 2 years, and have it inspected more often than that!

[Way2slow]

I've preached that for years, but most people seem to think they will last the life of the motor. Which, I guess that's true, when they go out, they usually take the motor with them.

That probably happened when you had the motor trimmed up using the motor to get out of some very shallow water or forgot you had it trimed all the way up in shallow water, started the motor to leave and left it running while you trimed it down. Five - ten seconds is all it takes on a dry pump. I can't help but laugh at all the people you see get to the ramp and crank there motor before they back it into the lake, I guess just to make sure it's going to run.

[Crowcommander]

X2 on that advice and have them change the lower grease in the foot also! Many folks have extended warranties on motors and the water pump is not on them. It only cost about $150 around here and well worth it considering what a new motor or power head  costs.

[Glenn]

Actually, I have a Yammaha HPDI - the water pickup is very low.  The prop has to be all the way out of the water before the pickup is dry.  And in the event I accidentally start it with the motor all the way off, I immediately shut 'er down.

So in this case, picking up some garbage makes more sense.  In fact, I just had a buddy of mine tell me he was running down the lake and the alarms went off.  After checking things out, he discovered one of those plastic grocery store bags wrapped around the lower unit, preventing water from getting in.

[simplejoe]

Let me ask you guys something, My Johnson 112 Spits water almost instantly after starting it but my  Evinrude takes about 5-10 seconds to start spitting water and its a strong stream do you think any damage is happening to the pump and the impeller?

                                                joe

[Way2slow]

NO.  It's very common for them to take several seconds for water to start coming out the pee tube, they have to fill the block with water before it comes out the tube.   The big V-4 and V-6 looper blocks can take a while before the water starts coming out of them.  

Running one dry is what kills the pump, the friction of that rubber impeller spinning at 800 - 6000 rpm on dry metal generates a lot of heat very fast.  If your lower unit is fully in the water and the inlets are not blocked, the pump is not running dry, it just take a few seconds to pump enough water.  

As mentioned though, if in doubt and it's been a coule of years, change the darn thing.  It's just not that expensive.  $35 for an impeller or less than $100 for the whole pump kit if you do it yourself and usually less than $200 to have a shop it.   When I buy a used motor, I always replace the whole pump first thing, then in a couple of years I just replace the impeller, (provided things still look good and not meet the fait of Glenn's).  A couple of years after the impeller change I replace the whole pump again, alternating between impellers and whole pumps so every four/five years the complete pump is replaced.

[simplejoe]

Thanks Way2Slow,  the impeller and pump are new the guy changed it right before I bought it he handed me the receipt and the old ones. I changed my other boat motor right before KY Lake Roadtrip so I know it's not hard. I try to keep up on maintenance on these motors, I don't want to be stuck somewhere out on the lake for something that could've been avoided.

Thanks makes me feel a little better now knowing I'm not damaging the assembly.

                                joe