# How Often are your Replacing the Impeller, Spark Plugs and Fuel Water Separator



## Finatic7 (Feb 14, 2020)

So I just completed the 100 hour maintenance (20 hour was completed by a certified Yamaha shop) on my Yamaha F115 that's on my Marquesa. I'm kind of OCD with maintenance on everything mechanical and always seem to take things too far. Having said that, I added replacing the spark plugs, impeller and seals and fuel/water separator filter to the standard oil, filter, gear oil, fuel filter, grease fittings and prop shaft 100 hour maintenance. The spark plugs and fuel water separator were super easy and if I already had to pull the plugs for inspection, I didn't see a reason to not change them. The fuel/water separator filter was much the same...too easy and cheap to not replace. I will say that there was much more crud in the filter than I had expected for a filter that has been in service for 10 months on a new boat and have only used Wawa non ethanol fuel:









Now for the impeller. At the strong recommendation of the Yamaha certified shop that I buy parts from, I also decided to change the impeller. Their recommendation was based on the fact that it is a shallow water boat and as such I run it shallow all the time. So I dug in night before last and pulled the lower to change it. I would say that replacing the impeller took about twice as long as doing everything else and this is the shape the the impeller was in:









To me it looked really good and was performing flawlessly. I don't think I needed to change it, but by the time you've pulled everything apart and now have to re-assemble I couldn't see not installing the new parts. Everything was pretty smooth except for the woodruff key (kind of a hassle)...just took a bunch of time.

So my question to everyone is how often do you replace your impeller and seals and also the spark plugs and fuel water separator? Do you inspect your impeller every 100 hours without replacing? If not every 100 hours - how often? I'm guessing that I didn't need to replace it...opinions?


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## flynut (Sep 7, 2015)

Usually a yearly thing for me. Around spring time is what I shoot for.


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## Smackdaddy53 (Dec 31, 2012)

X2 on flynut’s post for a stock outboard.
The woodruff key is easy to pop out with a flat screwdriver and hammer. Put the blade on the top edge of the key and hammer down and it will slide out the bottom.


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## Seymour fish (May 13, 2018)

Finatic7 said:


> So I just completed the 100 hour maintenance (20 hour was completed by a certified Yamaha shop) on my Yamaha F115 that's on my Marquesa. I'm kind of OCD with maintenance on everything mechanical and always seem to take things too far. Having said that, I added replacing the spark plugs, impeller and seals and fuel/water separator filter to the standard oil, filter, gear oil, fuel filter, grease fittings and prop shaft 100 hour maintenance. The spark plugs and fuel water separator were super easy and if I already had to pull the plugs for inspection, I didn't see a reason to not change them. The fuel/water separator filter was much the same...too easy and cheap to not replace. I will say that there was much more crud in the filter than I had expected for a filter that has been in service for 10 months on a new boat and have only used Wawa non ethanol fuel:
> View attachment 175744
> 
> 
> ...


operating under the " if iy aint broke, dont fix it" principle, my F70 impeller went 500 hrs of running skinny on hard sand , still making normal water pressure this was the limit as one vane cracked at autopsy. with Zephyr Cove low water pickup, the intake of sand is about zero, so longevity should be excellent, but will likely change every 300 hrs. the water seperator gets changed every 60-100 hrs depending on fuel quality. view this as critical. Plugs every 200-300, or if any motor issues. note: a bad plug can look absolutely normal


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## Finatic7 (Feb 14, 2020)

How are you determining fuel quality? Ethanol free is a no brainer for me as I have pretty easy access here in Florida and have always stayed with the same chain of gas stations (Wawa) as they are mostly new with new tanks, but am surprised by the amount of junk that came out of the filter. Always looking for a better option.


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## Finatic7 (Feb 14, 2020)

Smackdaddy53 said:


> X2 on flynut’s post for a stock outboard.
> The woodruff key is easy to pop out with a flat screwdriver and hammer. Put the blade on the top edge of the key and hammer down and it will slide out the bottom.


The screwdriver and hammer from the top edge is exactly how I tried to begin. Probably tapped it for 20 minutes with little success but deformation of the key. Called an audible and ran to the hardware store for a small cold chisel and alternated between hitting the bottom of the key directly toward the shaft and then down from the top. This only took about 5 minutes to break it free. To get the new key in, I ended up tapping it with a brass hammer which worked okay. Anybody know of some type of press tool that would work better for the next time?


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## flynut (Sep 7, 2015)

I usually change the hole water pump housing and impeller, gaskets, all together. Buy the kit. While your in there might as well do it all.


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## Smackdaddy53 (Dec 31, 2012)

Finatic7 said:


> The screwdriver and hammer from the top edge is exactly how I tried to begin. Probably tapped it for 20 minutes with little success but deformation of the key. Called an audible and ran to the hardware store for a small cold chisel and alternated between hitting the bottom of the key directly toward the shaft and then down from the top. This only took about 5 minutes to break it free. To get the new key in, I ended up tapping it with a brass hammer which worked okay. Anybody know of some type of press tool that would work better for the next time?


I’ve never had one that siezed up!


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## devrep (Feb 22, 2009)

fuel/water sep yearly (or so). impeller every 2 or 3 years and they always look good (they always do until they aren't). spark plugs uh almost never.


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## NealXB2003 (Jun 8, 2020)

I do impeller and fuel filter very other year. Oil changes (4 stroke) every year. Lower unit fluid every year or every other, depending on how much time I put on it.


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## SkiffaDeeDooDah (Jan 20, 2020)

Good info here on this thread - thanks all. Since silicone acts like a preservative or conditioner on rubber, I like to completely coat a brand new impeller with a thin layer of SuperLube Silicone Lubricating Grease, before installing it into the new housing. Keeps the impeller rubber from hardening as quickly, and the pee stream stays strong-as-new longer.


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## Kirc (Jan 18, 2020)

*"Impeller, Spark Plugs and Fuel Water Separator"*

4 Stroke 
1yr or 100 hr - impeller, spark plugs (& lower unit oil) / 50hr - water separator

2 Stroke
1 yr or 100 hr - impeller (& lower unit oil) / 50hr - spark plugs & water separator

also (after running most the fuel out), if you can:
annually jack the tongue all the way up, let it set a few days, pull the sending unit, run a hose all the way down to back / lower part of the fuel tank and pump at least a gallon out. Shocked the first time I did it,.......and for me, determined by all the s&%t I pumped out, the additive fix-alls were an absolute waste.


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## permitchaser (Aug 26, 2013)

Thanks for starting this thread. Since my back surgery I'm not dropping that 140 foot and not being able to get it back on. My local marine mechanic is a better option. Just changed my impeller and water pump. Why was your water separator full of gunck?. I don't use my boat as much as most on here. I change impeller about every 2 years, spark plugs every year. Water sep. yearly I use non ethanol.


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## Finatic7 (Feb 14, 2020)

permitchaser said:


> Thanks for starting this thread. Since my back surgery I'm not dropping that 140 foot and not being able to get it back on. My local marine mechanic is a better option. Just changed my impeller and water pump. Why was your water separator full of gunck?. I don't use my boat as much as most on here. I change impeller about every 2 years, spark plugs every year. Water sep. yearly I use non ethanol.


I’m lost as to why all that gunk was in there, considering I’m very consistent with where I purchase fuel and what fuel I’m purchasing. Not sure how to solve that, but if anyone has any suggestions..I’m all ears. I’m definitely going to pump some of the gas out of the tank as recommended by Kirc above. Thank you for the suggestion.


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## BrownDog (Jun 22, 2019)

Every 100hrs gets oil change, LU oil, and water separator/filter.

Impeller is usually an annual thing, more to make sure the LU bolts or anything doesn’t seize. Along with anodes.

I also repowered end of November and am getting ready to do my 300hr service.


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## mwolaver (Feb 6, 2014)

The impeller is a "broke vs efficiency" thing. As the arms take that permanent set, they lose efficiency. Yes, it will still pump and probably be fine. I think my yamaha manual says 300 hours for the pump, but I did it at 200. No, it's not worth the work to inspect it....replace it while you're there.

Seymour's "run to failure" experiment was great information.


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## SS06 (Apr 6, 2021)

I am going to use this northern tool filter/ funnel for all my pump fuel. My Wawa and CircleK gas have historically been "dirty".



https://www.northerntool.com/shop/tools/product_200578787_200578787?cm_mmc=Google-pla&gclid=EAIaIQobChMIrfin8YuE8QIVQx-tBh3xwADmEAQYASABEgImsvD_BwE&gclsrc=aw.ds&utm_campaign=FloTool&utm_content=22049&utm_medium=Automotive%20%3E%20Automotive%20Engine%20Repair%20Tools&utm_source=Google_PLA


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## Sublime (Oct 9, 2015)

Kirc said:


> also (after running most the fuel out), if you can:
> annually jack the tongue all the way up, let it set a few days, pull the sending unit, run a hose all the way down to back / lower part of the fuel tank and pump at least a gallon out. Shocked the first time I did it,.......and for me, determined by all the s&%t I pumped out, the additive fix-alls were an absolute waste.


I'm a big fan of this. I used to regularly pump E10 out of the skiff into the car with a little 12 volt fuel pump if I thought the fuel had been in there a while (4 weeks ish)


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## LastCast (Jun 13, 2012)

I typically change plugs, oil and filters once a year and the impeller every other year. It's probably overkill but I figure its to easy and inexpensive to no do it and take care of the engine


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## Backlasher (May 20, 2016)

While I should be more diligent in tracking the engine hours, I typically use the calendar for most services. Every spring (before it gets unbearably hot in the garage) I change the engine oil and fuel filter. I added the Racor S3213 fuel filter with stainless bracket and plastic see through bowl when I purchased the boat and mounted it below deck in front of the motor so relatively easy to get to for change out. Have seen very little debris in the bowl and have been running corn juice during my ownership. I also examine the small fuel filter under the cowl and change that out if it starts getting dark in color (usually every 3 or 4 years). I change the gear oil every two years (regardless of engine hours).

I probably change plugs every three years or sooner if I don't believe the engine is starting quickly or losing any performance.

I use my water pressure gauge to determine when it is time to change the impeller. If I see a consistent drop in pressure (5 lbs or more), then it is time.

I know this is probably another discussion but I am starting to pay more attention to the life of the batteries. I run two Optima Blue Tops (starting/house and 12V trolling motor) which have never let me down but thinking that I should go ahead and replace them at the 5 year mark.

And I do have a small notebook where I write down all services, dates, engine hours, quantities, brands, and part numbers as well as keeping a maintenance guide taped in the inside cover.


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## DBStoots (Jul 9, 2011)

Backlasher said:


> While I should be more diligent in tracking the engine hours, I typically use the calendar for most services. Every spring (before it gets unbearably hot in the garage) I change the engine oil and fuel filter. I added the Racor S3213 fuel filter with stainless bracket and plastic see through bowl when I purchased the boat and mounted it below deck in front of the motor so relatively easy to get to for change out. Have seen very little debris in the bowl and have been running corn juice during my ownership. I also examine the small fuel filter under the cowl and change that out if it starts getting dark in color (usually every 3 or 4 years). I change the gear oil every two years (regardless of engine hours).
> 
> I probably change plugs every three years or sooner if I don't believe the engine is starting quickly or losing any performance.
> 
> ...


Add your trailer tires to the list!


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## Backlasher (May 20, 2016)

I do. And bearings too. Rather than rebuilding the bearings I just replace the hubs (with bearings), pre-greased and ready to mount. They are relatively cheap and much quicker/easier than repacking old bearings. I also keep a new spare hub assembly in my trailering box to prevent ever having a bearing failure on the road (Murphy's Law).

I swapped out all the tires last year (two primaries and spare) even though I have never had a flat (just cursed myself).

Next on the list is to swap out my Amertrail torsion axel. Getting very rusty on the torsion axel ends....


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## Bruce J (Mar 4, 2018)

Backlasher, if you’re in Texas take your trailer to “Trailer Todd“ Garland at The Trailer Shop in Rockport. He just cleaned up the torsion axles on my Ameritrail (same age as yours) and said they should be good for another 10 years. They look good as new. I was sure mine would have to be replaced.


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## Ben Sheppard (Feb 1, 2020)

Regardless of the hours replace engine oil and lower end oil once a year minimum or every 100 hours of normal use, whatever comes first.
Replace water separation filter minimum of one a year.


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## Fliesbynight (Mar 23, 2020)

Backlasher said:


> And I do have a small notebook where I write down all services, dates, engine hours, quantities, brands, and part numbers as well as keeping a maintenance guide taped in the inside cover.



Backlasher,

The information on quantities, brands and part numbers is so you can buy the right stuff, or are you keeping track of the replacement parts? If so, why? I am new to boating and am trying to figure some of the out. Tracking everything appeals to my CDO (OCD with the letters in the correct order) but I'm not sure if that is what you meant.


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## Backlasher (May 20, 2016)

Fliesbynight said:


> Backlasher,
> 
> The information on quantities, brands and part numbers is so you can buy the right stuff, or are you keeping track of the replacement parts? If so, why? I am new to boating and am trying to figure some of the out. Tracking everything appeals to my CDO (OCD with the letters in the correct order) but I'm not sure if that is what you meant.


The answer is yes - I tape the factory recommended maintenance schedule in my notebook along with a couple of engine part diagrams and write down part description, part number, and quantity whenever I replace anything (along with the date).


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## Fliesbynight (Mar 23, 2020)

Backlasher said:


> The answer is yes - I tape the factory recommended maintenance schedule in my notebook along with a couple of engine part diagrams and write down part description, part number, and quantity whenever I replace anything (along with the date).



Thanks for the reply. Sounds like a good practice to me.


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## jesseoshea (Jul 10, 2018)

I change my water pump impeller every other year if it’s functioning well (strong stream). The plugs are changed every season.


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## JC Designs (Apr 5, 2020)

I always have and always will recommend all annually or sooner if commercial use no matter! It is cheap insurance and beats the hell outta a ruined day on the water!!! Time is precious, maintenance parts are cheap!


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## scissorhands (Apr 8, 2012)

8 months for the impeller. Did the usual oil change, fuel filters, lower unit oil, fuel water separator while I was at it.


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## FlyBy (Jul 12, 2013)

scissorhands said:


> 8 months for the impeller. Did the usual oil change, fuel filters, lower unit oil, fuel water separator while I was at it.
> View attachment 181225


Dammit, man.


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## mwolaver (Feb 6, 2014)

scissorhands said:


> 8 months for the impeller. Did the usual oil change, fuel filters, lower unit oil, fuel water separator while I was at it.
> View attachment 181225


That is not normal wear. Extreme service or intake clog? I'm sure you know.... An impeller will look mostly new, except for the set of the arms, at 200 hours.


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## scissorhands (Apr 8, 2012)

mwolaver said:


> That is not normal wear. Extreme service or intake clog? I'm sure you know.... An impeller will look mostly new, except for the set of the arms, at 200 hours.


I've had some pretty bad impellers in my day. That impeller above was still producing 12-14psi. while running, but had a hard time pumping water at idle. They are made to wear out.


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## bob_esper (Jun 3, 2021)

I change all oils once a year and water pump every other year. Unless you're starting the motor out of the water, raising it too far out of the water, or running through sand it should honestly last 3+ years easy.


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## Mako 181 (May 1, 2020)

The more you use the boat the longer the impeller will last to a point. Dry rot caused by lack of use kills them. 
That one in the pic looks to have very unusual wear.


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## DBStoots (Jul 9, 2011)

scissorhands said:


> I've had some pretty bad impellers in my day. That impeller above was still producing 12-14psi. while running, but had a hard time pumping water at idle. They are made to wear out.


PSI on my F70 is over 30 when running. That seems inadequate. Good thing you changed it out.


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## scissorhands (Apr 8, 2012)

DBStoots said:


> PSI on my F70 is over 30 when running. That seems inadequate. Good thing you changed it out.


Brand new it was 18-20 psi, my friend Suzuki 60 only gets about 10 psi if he is lucky. Different brands gonna all pee different


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