Waterpump SHOULDS and SHOULDN'TS

[78ImperialT]

Alright guys...I know that alot of you are mechanics and pros and know exactly what you are doing. I also know that alot of us (including myself) aren't even close.

I spent alot of time and alot of money to rebuild a boat to almost lose it because i had a bad waterpump.

I propose that we give tips and techniques for everything waterpumps and post pictures of what waterpump impellers should look like and shouldn't look like.

I know this would have helped me and might help someone else.


I'll go first:

1) just because there's water coming out of the peehole doesnt mean you have a good pump

2) when your buddy says "if it aint broke dont fixit", swap the impeller

3) just because you replaced the impeller 6 years ago and never used the motor doesn't mean you shouldn't swap it before using it again. the impeller is under pressure even when not in use (this i did not know).


thanks for all the input I / We can get!!!

 

[tashasdaddy]

Re: Waterpump SHOULDS and SHOULDN'TS

impeller should be changed every 2 years, whether the motor is used or not. they actually last longer on motors that are used.

i would go into more detail or changing them but different year and hp, have different steps.

 

[CATTOM]

Re: Waterpump SHOULDS and SHOULDN'TS

I have a 75 hp johnson that I just got ,its been sitting a while.
When I took it to the lake it ran good but when I idled along the hot light would come on and go off ,when I speeded up it would go off again.
Its a 1975 model ,do I drop the lower unit off to replace the impeller?
DOES anyone have a schematic of the motor ,or walk me through it?
Thanks
CATTOM

 

[Rick.]

Re: Waterpump SHOULDS and SHOULDN'TS

CATTOM: Your hijacking someone's thread here. Normally not a good thing to do when you have a question. Go to this link and find a parts break down of you specific model. Best of luck. Rick.
http://shop2.evinrude.com/ext/index.aspx?s1=aa3c9a1ab5f105fbe638113b543231ae

 

[CATTOM]

Re: Waterpump SHOULDS and SHOULDN'TS

Sorry about that !
CATTOM

 

[Les Robb]

Re: Waterpump SHOULDS and SHOULDN'TS

It isn't hard with your motor, start at top and take out the bolt holding your shift linkage. ( It will be easier if the flame arrestor muffler is off the carbs) Pay attention to the bolts you can see and also the one hidden under the removable trim tab. You can mark the position with a majic marker so you don't have have to think about it on reassembly. Tilt the motor up so you can see all the bolts from underside. It shouldn't take more than a little coaxing to get it loose and if you think you have to pry it off you missed a bolt. Replace all seals around water pump and tube and don't forget the o-ring at the top of your drive shaft. Make sure you align the water tube with pump outlet and make double double sure your key (lock) dosen't fall out when you put the new impeller in. Turn the drive shaft clockwise (looking at it from above and you will be able to hear the impeller turning. Don't know for sure but I have always used Vaseline for lubricating my water pumps on reassembly.

Good luck

 

[Les Robb]

Re: Waterpump SHOULDS and SHOULDN'TS

Your right he did kinda jump in on someone's post but since original did ask for tips etc I figure it wasn't like a major steal. Anyway we're all here to learn and help if we can.

Safe boating ya'll

Rick I was typing while you were posting and yes you were right.

 

[iwombat]

Re: Waterpump SHOULDS and SHOULDN'TS

My replacement rules of thumb.

If you think you might be due for a new one - replace it.
If you can't remember when the last time you replaced it was - replace it.
If it's new to you and you don't know how old it is - replace it.
If the guy you just bought it from says it's new last year, but can't produce the paperwork - replace it.
If it's been sitting unused for more than one full season - replace it.
If it's over 2 years old - replace it.


Get the picture?

 

[Les Robb]

Re: Waterpump SHOULDS and SHOULDN'TS

Amen to Iwombat, that will be the cheapest insurance you can ever put on your motor. For you newbies, think about driving your brand new car with a blown radiator hose till it finally siezes up and stops deader than a hammer. That pump is about like your heart, if it ain't pumping your in trouble.

 

[78ImperialT]

Re: Waterpump SHOULDS and SHOULDN'TS

no prob on the hi-jack...can never get too much info on the waterpump.

as far as the 75hp johnson...wow...i wish i had somebody telling me that stuff. i tried for hours to get the foot off. i removed the 4 bolts that were visible (2 on each side), i removed the one in the middle in the back, i even roved that alignment looking thing and got the hidden bolt (took a while to figure that one out). i pulled, yanked, twisted...it wouldnt drop. i was ill!

...then i found the shifter linkage bolt...i felt like a dummy...

fell right out...on my foot!

so...make sure you have a second set of hands or some sort of stand or box or anything other than your foot to catch it when it falls.

btw...good advice on the oring at the end of the drive shaft and that key at the impeller.

 

[LiLGrady17]

Re: Waterpump SHOULDS and SHOULDN'TS

Wombats has the right attitude, Cheap insurance..

People will spend money on dual batts, epirbs, kicker/secondary engine power, seatow/us boats memberships all in the effort to not get stuck, and still not religiously schedule impeller changes..

 

[78ImperialT]

Re: Waterpump SHOULDS and SHOULDN'TS

...is this all you guys have got?

any other tips?

 

[Sea18Horse]

Re: Waterpump SHOULDS and SHOULDN'TS

Personally I find it interesting that the old parts manuals show the impeller in the "as installed" shape (impeller blades curved) rather than in the "as new" new shape (impeller blades straight). I believe that in a lot of cases this leads to problems. People pull their impeller out, see that it looks just like the one in the picture and conclude that it's just fine. They don't realize that at low speeds the blades have to flex. Because the shaft and housing bore is offset. (Displacement pump mode)

Cheers..............Todd

 

[iwombat]

Re: Waterpump SHOULDS and SHOULDN'TS

I'm not sure what you're looking for as far as tips goes. A lot of it is model specific. About the only thing I can think of as a generic tip is to put soapy water on the impeller, press the housing down over it, and turn the shaft (or prop if you do it by that method) in the normal direction of rotation while pushing down on the housing. They go in a lot easier lubed up and rotating.

By far, most of the problems people post about here is removing the LU prior to doing the pump replacement. And, probably the majority of those is either disconnecting the shift rod, or missing the bolt under the trim tab.

 

[Silvertip]

Re: Waterpump SHOULDS and SHOULDN'TS

Here are my suggestions on impellers and overheating in general.

1) The water pump pumps water through the engine.
2) Just because the pump is pumping water does not mean the engine won't overheat.
3) A thermosat that is stuck shut will likely cause an overheat at idle.
4) A bypass valve that is stuck shut will cause overheating at mid to higher throttle settings.
6) A bypass valve or thermostat that is stuck open can cause overcooling which generally results in poor idle quality.

Although frequent replacement of the impeller is recommended, it is no guarantee you won't fry the engine due to an overheat. For these reasons I'm a staunch supporter of Cylinder Head or Water Temp and Water Pressure gauges.