Water pump impeller price and quality

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
frontier
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Water pump impeller price and quality

Postby frontier » Sat Sep 22, 2018 8:03 am

The prices for a new outboard motor water pump impeller (part only) vary a lot. For example, the prices of new six-blade 3-inch-diameter impellers to fit the newer 30 to 60-HP Mercury outboards range from $11 to over $60. Many people say you should change your impeller every year or two. I wonder if cheaper impellers have to be change sooner? It seems like a you-get-what-you-pay-for situation. The OEM impeller on my old Mercury 40-HP engine (used on a 13-foot Boston Whaler boat) lasted 15 years or longer.

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Phil T
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Re: Water pump impeller price and quality

Postby Phil T » Sun Sep 23, 2018 10:45 am

In my experience, the ones recommending impeller changes every 1-3 years are in the replacement business. If running in salt and don't flush the engine I say 3-4 years as a precaution.

I prefer OEM branded parts.
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Jefecinco
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Re: Water pump impeller price and quality

Postby Jefecinco » Sun Sep 23, 2018 12:01 pm

I believe impeller change intervals should be dependent on how/where you use your boat. In our case we frequently operate in sandy bottom shallow water conditions lacking in NAVAIDS. This helps keep our engine skeg nice and shiny and bare of paint but the impeller may not fare too well. We change impellers every four years or so.

If your engine skeg paint is not worn and your engine cooling water tell tale remains strong and constant perhaps a ten year interval is more appropriate.
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dtmackey
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Re: Water pump impeller price and quality

Postby dtmackey » Sun Sep 23, 2018 10:16 pm

I've seen impellers fail within 1 year, run in good clean water, you just never know. Personally I limit impeller life to 3 years max. Remember, it is rubber an the vanes are very "flexed" and as rubber ages it can take a set. I've seen the rubber separate from the inner shaft collar enough times not to play the game in changing out a $40 part.

I'll go thru my pics tomorrow and see if I have one of the several failed impellers I've seen.

D-

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GoldenDaze
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Re: Water pump impeller price and quality

Postby GoldenDaze » Mon Sep 24, 2018 10:04 am

I replace my impeller every 3 years. I mostly boat on deep fresh water, and the old ones come out looking brand new. But considering the consequences of impeller failure, it seems like cheap and easy insurance. For the same reason, I buy brand-name parts. Frequent replacement also ensures that the lower unit mounting bolts don't have time to freeze up; everything always comes apart nice and easy.
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ConB
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Re: Water pump impeller price and quality

Postby ConB » Mon Sep 24, 2018 4:01 pm

I buy OEM. Cheap impellers are probably made by the same Chinese company that make tires and hoses that won't hold air.

Con
!987 Outrage 18 / 1987 150 hp Johnson & 1969 13 / 30hp Johnson tiller

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Dutchman
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Re: Water pump impeller price and quality

Postby Dutchman » Tue Sep 25, 2018 7:45 am

OEM every 10-years or longer is fine as long as your cooling workssame tell tale.

Yes salt water and sand will shorten impeller life.

Use your own discretion.

Impellers can fail in one hour or 500 hours. I've had impellers that were 23-years-old used in fresh water before I changed them.

Replacement is money driven. If you can do it yourself, do it when you want for feeling better reasons.

If you need to use a mechanic make sure replacement is really needed.
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Wirenut
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Re: Water pump impeller price and quality

Postby Wirenut » Fri Sep 28, 2018 8:07 pm

I had an Evinrude 80-HP engine impeller last 17 years. It was replaced in a Fall, and the engine blew up after about three hours running in the next Spring.

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Re: Water pump impeller price and quality

Postby Jefecinco » Sat Sep 29, 2018 11:11 am

That would make me seriously suspicious of the mechanic.
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Wirenut
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Re: Water pump impeller price and quality

Postby Wirenut » Sun Sep 30, 2018 9:09 pm

I was the mechanic. [The cause of the engine blowing after the impeller was changed] was totally unrelated to the cooling system.

dtmackey
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Re: Water pump impeller price and quality

Postby dtmackey » Sun Sep 30, 2018 9:21 pm

I like to replace my impellers within a 3 years period in the 4 outboards I run. In my Cummings diesel and Northern Lights diesel genny, I also go 3 years, but in the off season I also remove the impeller from the housing so it can relax and the vanes do not take a "set" and it only takes 10 minutes on the diesels.

Personally I do not feel that under 3 years is necessary unless you run in sandy water or have dry-run the motor. Otherwise it's like handing money over to the dealer (I do all my own maintenance).

Over 3 years I feel adds risk to the ownership equation. We all know someone that has run for well over that, but the risk factor does go up and since parts are inexpensive, it doesn't hurt replacing.

Over the years, I have seen a number of failures of impellers in the first year they were installed. I do not have pics of them all, but share this one of a Merc outboard with a brand new impeller with no more than 5 hours of runtime. The inner collar separated from the rubber and the motor lost cooling and overheated. Since this was a friend of mine on our summer cruise, I know how the boat was run and we diagnosed after the motor overheated. It was not dry run and it was installed correctly. It just failed.

Image

I've seen this same concern occur on Evinrude, Yamaha, Tohatsu outboards and Volvo and Westerbeke diesel inboard impellers over the years working on boats.

D-

dleopoldi914
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Re: Water pump impeller price and quality

Postby dleopoldi914 » Thu Oct 25, 2018 10:22 am

frontier wrote:...Many people say you should change your impeller every year or two...


Every year or two? The former owner [of my outboard engine] said he [changed the impeller four] years ago. I was going to change [the impeller] as a maintenance item but [the old owner asked] "Is [the overboard confidence stream] ok" and my answer was "yes." He said, "ok. Why change it?"

I am the type of guy that would rather be safe than sorry. I actually have all the parts to do the thermostat and the impeller. Maybe two hours in labor.

I am new to boating and not mechanically inclined so probably should pay [to have the water pump impeller changed]. Pulling the lower unit seems like a lot that can go wrong. Plus [the engine power is] 90-HP and [the gear case] will be heavy.

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Re: Water pump impeller price and quality

Postby jimh » Thu Oct 25, 2018 2:01 pm

The weight of the gear case and the complexity of re-installing everything correctly are two reasons why I hire an experienced and trained mechanic to service the water pump on my relatively new 2010 E-TEC engine.

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Re: Water pump impeller price and quality

Postby dtmackey » Thu Oct 25, 2018 10:34 pm

jimh wrote:The weight of the gear case and the complexity of re-installing everything correctly are two reasons why I hire an experienced and trained mechanic to service the water pump on my relatively new 2010 E-TEC engine.


I don't blame you for going to the dealer. The Etec does take more time and effort than other motors out there. Side panels must be removed and also the shift rod pin, before you can attempt to remove the lower unit. After a couple times you can do it quickly, but it'd be so much easier if they had a setup like the Yamaha shift shafts where it's rotational so it uses a splined shaft that comes apart easily with minimal prep. It does make it a bit easier if the L/U is removed with the motor tilted about 1/3 to 1/2 way.

D-

fno
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Re: Water pump impeller price and quality

Postby fno » Fri Oct 26, 2018 2:24 am

Anecdotal comments both here and other sources indicate that smaller horsepower(20-75hp) engine impellers can last a lot longer than those on higher horsepower engines (90-300 hp). I think that's Bull$#!+ The thing to consider is the cost to benefit ratio of replacing the impeller say every 2-3 years vs. 5-10 (or even 17 yrs) years as advocated by some. If your engine is worth $2,00-$5,000.00 and the impeller costs $40 why not wait till the bitter end. With a $20-25K engine relying on a $40 impeller I would consider changing it every two years or even one if conditions compel. Another fallacy in this conversation is the reliance on the motors telltale stream to indicate the lifespan of an impeller. The only thing the telltale is reporting is that the impeller is in good shape and doing it's job at the exact moment you looked at it. It is providing no guidance whatsoever that the impeller will be working on the next outing or even the next 10 minutes. My thought is to replace every two years based on 100 hours per year in both salt and fresh water. That's $20 per year of use and is peanuts for most. One less thing to worry about while enjoying the outdoors and your family and friends on the water.

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Re: Water pump impeller price and quality

Postby Don SSDD » Fri Oct 26, 2018 5:34 am

Judging by the reports of failures of new impellers after as little as 5 hours, it may be you have as big a risk of impeller failure by changing an impeller every year or 2 as by leaving it there for 5-10 years? You may get one of those bad new ones when you buy a new one more often?

I use the quantity of water from the telltale as a sign and on the last 2 used outboards I bought, I changed them both after buying them. I would change them every 5 years unless the telltale stream declines. My use is in salt water and almost never near any sand.
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dtmackey
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Re: Water pump impeller price and quality

Postby dtmackey » Fri Oct 26, 2018 8:54 am

I think we can all agree that as an impeller ages it:

- Sees additional wear from use
- The rubber dries out and vanes can crack
- The mechanical bond with the internal collar can weaken (yes, I posted a failure of a new impeller, but that is rare)

So if we all can agree that an aging impeller sees a higher potential of failure as the years add up, then for the minimal cost of replacement, it makes sense to replace. Relying on the telltail stream is IMHO poor judgement since one does not operate an outboard with their eyes trained on the telltale stream the entire time a motor is running. Even if one has a water pressure gauge, how often are you looking at it?

If your motor is running at cruise speed and the impeller fails, it takes very little time for the motor to heat up and run the risk of heat seizing. When this happens, the cost of the impeller replacement will seem cheap compared to a rebuild or possible replacement of the motor.

I realize people will fall back on what they've heard or what has worked for them in the past, but for others minimizing those risks is the peace of mind one has when taking the family out for a day on the water or cruising 25 miles offshore for deep sea fishing.

D-