Several Questions

Why do you guys change the water pumps out? Do you not want it to quit while your on the water? How long would they last without changeing one out? Can I do it myself? How much do they run?(00 johnson 150)

I have always considered it very cheap insurance. I change mine out every year of so. You can change it yourself, however I have always had Mercury motors and am not familiar with Johnson motors. I am sure there are websites that will walk you through it without a problem.

It's around 50 bucks for the pump and 30 or so for a manual. Tells you exactly how to do it. As HasBen said it is cheap insurance. If it does go out on the water just a minute will burn up the motor. Better to be safe than sorry.

Simple Math

1 pump 50 bucks

Change every two years over 12 years of boat owner ship 50 x 6 = 300 dollars over 12 years.

One blown motor even say a 15 HP hand tiller will cost 2,000 dollars minimum say you have a 75 Merc you are looking at 7,000 dollars or more. In many cases a new motor might be well over 10 grand.

Now if you push your pump to 3 years you may get away with it but over 5-10 years odds are you will blow your motor sooner or later.

So it is simple math and probability,

It's a do-it-yourself job for the reasonably self-confident. First time it's kind of intimidating, but you can do it.

Reason why, is the pump (unlike your automotive waterpump) is designed to function in dirty water, sand, grit, impurities, whatever - trade-off is, the impeller will wear out. In fact just a minute or two of dry running will damage it.

here's a video tutorial:
http://www.themarinedoctor.com/cgi-bin/YaBB.pl?board=Cot;action=display;num=1113876330

You'll need a manual for specific instructions on removing & reattaching the L/U - Seloc or Clymers is okay, but best bet is an original OMC service manual - www.marineengine.com or www.kencook.com

You could probably find a lot of folks run 10, 15 years with original water pump...but it's pretty cheap maintenance and a failure is catastrophic. Your Johnson probably has SLOW mode, where it'll cut back to half RPMs if it overtemps, but that's an emergency "limp-home" feature - wouldn't be prudent to plan on using it.

Change out the impeller every couple or three years, or the whole pump kit if the inside housing gets scored. More often if you run a lot in shallow sandy water or if you churn up the bottom a lot. Or if your telltale gets noticeably weaker. Or any sign of overheating.

[note: if I recall correctly, in the video he re-uses the impeller - to me it's a lot of trouble to drop the L/U & disassemble the pump, so I say, replace the dang thing regardless.]

Why change it???? Listen to everyone on this topic! Boat ownership equals MONEY for normal maintenance.

Even if a mechanic does it for $125 its much cheaper than a rebuilt powerhead! Changing the water pump is normal along with carb rebuilds about every 3 years or so. AND tuneups COMPLETE and FULL every other year.........at least......and changing the lower unit oil every year. Its part of owning a boat.

Well isn't that a design flaw? I suppose it is just part of the maintaining your boat aspect, but seems to me if you change it once a year, then something is wrong somewhere.

.....excuse me while I go to the boat shop for a water pump.....

I think every year is over kill myself but say every 2-3 years for most folks makes a lot of sense. If you are a guide and on the water 4-5 times a week, every week of the year then yearly makes a TON of sense,

Using it that often Jack is better than using it once or so a month. Using it keeps it pliable. Sitting, it will take on a "set" which is a real killer. I have had numerous Johnsons and Evinrudes that went 3-5 years easily. The 2 Mercury/Mariners I have had, about 2 years max and if I didn't use it much, then 12 months.

steve, you don't wait for them to break before you change 'em, do ya?

I've been following this thread and coincidentally just today my water pump went out on my workhorse Evinrude 48 SPL. I noticed the "pee" stream was a just little weak when I started but seemed to be running fine and staying cool (good thing it was a cool day today, too, I suppose) so I proceded to head out for a day of fishing but planned to stay very close to the marina and not use my big engine very much just in case. Throughout the afternoon, the pee stream got weaker and weaker. And by the time I gingerly eased back into the marina at the end of the day it was just barely dribbling out. I had just tested my overheat horn a few weeks ago as part of routine maintenance so I was relying on that to tell me if I needed to shut it down. It never sounded. All day I only put about 30 minutes on the engine during which time the pee stream went from a little weak to just barely a dribble. Impeller service is now in my immediate future.

Lessons: 1) I just had my water pump professionally serviced (along with the lower unit) in May and I've used my boat regularly since. Probably put about 100 hours on the engine total since the impeller was serviced. I've not abused the engine or ran it dry at all. Obvious to me now, impellers may only last as little as 100 hours or so even under good conditions. 2) Surprisingly, it gave plenty of warning before it went. I got about 30 minutes of warning run time before it went completely, but only becasue I'm in the habit of watching the pee stream regularly. I don't know if this is typically the way they fail, but this is the only one that's ever failed on me and it did so over a 20-30 minute time span. Be careful and watch that pee stream.

Bottom line: take to heart what everyone said on this thread. Consider water pump service a regular service item and do it every year when you get the lower unit gear oil changed. Even having just done the impeller service in May, I only got about 100 hours out of mine before it went. As the Nike ad says: "Just do it."

Disclaimer: I haven't taken it apart yet to confirm it was in fact the impeller, but I run only in clean open water and did check the intake screens for blockage (there was none). I suppose it still theoretically could be some other sort of blockage but the gradual weakening of the pee stream over 20-30 minutes of running indicates to me an impeller coming apart. Also, today was the first time in about a month the boat's been in the water, lending creedence to the "regular use keeping the impeller pliable" theory.

Happy boating!

darren,
before you drop the L/U, look under the hood at the telltale supply line, they develop leaks sometimes if they get old, also take a thin wire or something and check if the nipple at the water discharge outlet is blocked - insect or something. If the pump looks okay, could be a blocked water passage, corrosion or something in the thermostat housing that sort of thing. bits of the old impeller working their way through the system.

good luck!

I change my impeller every 2 years.

Change Plugs, Fuel Filter, Lower Unit Oil every year.

Maintenance is part of owning a boat.

Mine gets changed every year.....running the shallows like i do, its just cheap insurance. Also get a water pressure gauge it will help you keep track of your pressure and then you can also tell whats going on without looking back at the telltell when your pressure starts to drop you need to figure out whats going on.

Thanks jtexas! The first things I checked were the telltale hose and the nipple. Hose leak-free & nipple clear. Didn't think of the thermostat & housing though. I'll check those next. Hopefully, it's not some blocked hard-to-get-to passage but a straight impeller failure. Pretty easy to change that out. An internal blockage might be another matter though. Thanks for the suggestions. Might also look into the pressure guage. It might help that crick I've got in my neck!