Are all impellers made equally?

Tim Good

Tim Good

Well-Known Member
Joined
26 Feb 2010
Messages
2,888
Location
Bristol
Visit site
I replaced my impeller in my Perkins 4.236 2 years ago. The one I took out was fine but I replaced anyway as it has been in there a long while. Whilst there I added the new style speed seal.

Anyway we’re now two years on and I thought I’d take a look and found the impeller in poor condition. 3 blades ready to come off fairly soon.

So I’m about to order more and wondered if some are better than others and if one brand tends to out shine the rest? I noticed initially ASAP sell Jabsco ones and eBay has some by CEF. The latter being cheaper.
 
I'm sure there are better quality impellers on the market than others but impellers are not the type of part that you use until it wears out. They say you should replace them every year (or after so many hours) so as long as they don't disintegrate before that time they have done their job.
 
coopec said:
I'm sure there are better quality impellers on the market than others but impellers are not the type of part that you use until it wears out. They say you should replace them every year (or after so many hours) so as long as they don't disintegrate before that time they have done their job.
Click to expand...

Who is the "they" who say that you should replace them every year? Or after how many hours?
 
I replaced my impellers earlier this year .
The previous impellers had been 3 years and just started to split slightly at the root of the vanes.
I thought that was good util some other people informed me they leave the impellers in service for a decade!
 
By the way the impellers I fitted earlier this year are the CEF brand. So it remains to be seen what they look like in the spring.
However no issues that I am aware of after 90 engine hours use.
 
My marina neighbour still has his original impeller from 1995. Yes you read that right, 1995.
Every few years he checks it, and puts it back. 3 cylinder Yanmar
Boat used weekly in summer, hardly at all in winter.
He closes his intake seacock routinely at shut down - no idea if this is relevant, but he thinks it is.
I remain flabbergasted!
 
I check mine annually. Any signs of weakness - cracking at the base of the vanes or bent vanes, and I replace it. I usually get several years out of it. I also remove a good impeller if I come out for the winter, so it doesn't stay in one place without moving for months.
 
I don't buy Johnson impellers, which used to break up annually.
Jabsco, in my size -653001, never do and the present one has just started to show signs of stress after 4 years and c400 hours
 
NormanS said:
Who is the "they" who say that you should replace them every year? Or after how many hours?
Click to expand...

Various engine service schedules specify that the impeller must be changed annually or every xx hours.

Curiously, different engines/manufacturers will specify different schedules, but they will be using the same water pump. There is no logic behind having to change an impeller annually in one engine, when the same impeller in another engine has a 4 year schedule.
 
Years ago, when I bought my first boat with a Yanmar, I was told that there were a lot of poor quality impellers around, a bad batch prone to early failure, so if you had a good one, keep using it.
I was once on a boat where the rubber bit of the impeller came loose from the brass boss. I fixed it with superglue. I believe the owner used it for the following year.
 
NormanS said:
Who is the "they" who say that you should replace them every year? Or after how many hours?
Click to expand...

How many hours the motor was running every season, the conditions and the type of motor will determine the life of the impeller. I will be running my Perkins 4-108 everyday as I do not have a separate generator.

You ask who "they" are who say the impeller should be replaced every year. If you do a google you'll get plenty of sites that state that e.g.

Replace all impellers at least once every year, or sooner, depending on the engine duty. When the installation is correct an impeller may last for several years, but it is always advisable to stick to a schedule of preventative, rather than corrective, maintenance.

https://www.jamestowndistributors.com/userportal/document.do?docId=676
 
RichardS said:
One has to ask the question "How often do you change the impeller in your, non 2.3 Honda, outboard?"

The answer is, possibly, never. :)

Richard
Click to expand...

Bit of an own goal, there, Richard. My Honda 2.3 outboard is air cooled :)

I replace my impeller every year, immediately prior to launch. Many years ago, I had an impeller throw a blade. It was my first year of ownership of a 3 year old boat so I had no evidence of its age. I was never happy with the thought of rubber debris clogging the water heat exchanger.

Now contradicting myself, I have 2 outboards, I also have the ubiquitous Tohatsu 2.5, it's probably 15 years old, probably done less than 10 hours and I don't even know how to find the impeller, never given a thought to changing it......perhaps I should.
 
If people don't test the things to the limits of use there will be no raw data to assist in buying decisions.
There will be no motivation for Jabsco to provide a better product than Johnson or to continue providing better than minimum durability.
I reckon if we buy crap that is what will be produced, viz the Chinese products in our dustbins.

I am not surprised that retailers recommend changing things annually. My Beta manual says: Inspect every year and replace as necessary
 
But it depends on the amount of use. Some 40 ft yachts will heat water with a calorifer, carry all the drinking water, do all the cooking using gas, don't have an auto-helm but have solar panels. My 40ft yacht will have a water-maker, inverter, microwave, bread-maker, auto-helm and electric hot-plate. I will have to run my engine everyday.
 
coopec said:
My 40ft yacht will have a water-maker, inverter, microwave, bread-maker, auto-helm and electric hot-plate. I will have to run my engine everyday.
Click to expand...

You'll be popular in quiet anchorages:)

I haven't even looked at my impeller for several years, plenty of water being pumped through and temperature stable so it's obviously still working. Outboards work fine for years without being checked annually in most cases so, what's the difference?
 
Engine and water pump manufacturers have to be conservative in their estimates of impeller life. If they say every year, that means they expect as near as dammit 100% of impellers to last a year. That implies a mean time between failures of 3 years or more.

I reckon on a fairly conservative maintenance schedule - check and replace if necessary, simply because the consequences of losing a blade somewhere inside the engine are not something I want to have to deal with.
 
Well said Steve.

When the motor is working hard (to avoid a nasty/life threatening situation) the motor packs it in........... (I'll keep a close eye on mine)
 
You must log in or register to reply here.

Share this page

Top