Reply
 
Thread Tools Search this Thread
 
Old 08 August 2019, 14:20   #1
Member
 
Country: UK - England
Town: Ipswich
Boat name: Click and Collect
Make: Valiant and Narwhal
Length: 4m +
Engine: Outboard
Join Date: Sep 2016
Posts: 1,030
That old Change your impeller every year debate

Got my Brothers boat ready for him to go boating in. He does nothing to it and I don't think he has started it in over a year. He/We have owned the boat over 6 years and it has never had a new impeller. Not sure how long the one in it had been in before we bought the boat.

I Charged the battery and it started after about 4 attempts. Petrol in tank very old.

It seems to run ok and pumps water like a trojan .




Makes you think !
__________________

__________________
Bigplumbs is offline   Reply With Quote
Old 08 August 2019, 15:03   #2
Member
 
The Gurnard's Avatar
 
Country: UK - Scotland
Town: Stirling
Boat name: The Gurnard
Make: Quicksilver
Length: 4m +
Engine: mariner 25hp 2s
Join Date: Jul 2013
Posts: 1,246
I am no expert Big Plumbs but would imagine the impeller is like everything..if you dont use the boat much..it will last for years. I do my own servicing and check my impellers every winter but only replace them when I think they require replacing.

Example my 6HP Yamaha Four stroke averages around 200 hours per year. I check the impeller every winter and decided to change it after three years of use..approx 600 hours of running. It was still in reasonable conditions but the ends of the blades were wearing flat and it was starting to loose its spring feeling when I bent them..if that makes sense.

So yes..you are correct they could be fine..but if it was my OB ..I would at least check their condition. Simply because if they fail at sea..(and you have no idea what shape they are in ?) ..they could cause a loss of life. If not yours or your brothers ..someone elses if the RNLI are attending to your problem and someone else gets into serious trouble. Admittedly .. very unlikely .. but not something I could live with if it happened to me .. simply because I ignored checking a vital part of the engine that does wear out.

Does my reply make you think ?

PS..I don't replace my plugs every year either..I keep them going until I think they are done..but I check them regular too ..and carry a spare set on the boat
__________________

__________________
The Gurnard is offline   Reply With Quote
Old 08 August 2019, 15:14   #3
Member
 
Country: UK - England
Boat name: Bluefin
Make: Ribcraft
Length: 5m +
Engine: 150hp
MMSI: Ex Directory
Join Date: Oct 2015
Posts: 239
Quote:
Originally Posted by Bigplumbs View Post


Makes you think !

Certainly, modern merc 4 strokes are impellor change every 3 years or every 300 hours and TBH I have never changed an impeller as part of an annual service, but I do inspect it every year ............

At 6 years you really need to have a good inspection for the rubber cracking at the root of the vanes ...........
__________________
gpsguru is offline   Reply With Quote
Old 08 August 2019, 15:42   #4
Member
 
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,489
Quote:
Originally Posted by Bigplumbs View Post
It seems to run ok and pumps water like a trojan .

Makes you think !
I'm thinking:

- why would someone think it would have failed in storage.
- how long will it be till a vein tears off and stops pumping properly.
- when a vein tears off will little bits of the rubber break off and block up the water channels
- if it was as simple as failing when testing in a tank rather than underway then people wouldn't replace routinely
__________________
ShinyShoe is offline   Reply With Quote
Old 08 August 2019, 16:31   #5
Member
 
Country: UK - England
Town: Ipswich
Boat name: Click and Collect
Make: Valiant and Narwhal
Length: 4m +
Engine: Outboard
Join Date: Sep 2016
Posts: 1,030
Answers below in red

Quote:
Originally Posted by ShinyShoe View Post
I'm thinking:

- why would someone think it would have failed in storage. They think the Rubber holds its bent position
- how long will it be till a vein tears off and stops pumping properly. Who Knows
- when a vein tears off will little bits of the rubber break off and block up the water channels Could do like all the other rubbish that is sucked into the raw water intake
- if it was as simple as failing when testing in a tank rather than underway then people wouldn't replace routinely Many don't replace routinely
__________________
Bigplumbs is offline   Reply With Quote
Old 08 August 2019, 16:33   #6
Member
 
Country: UK - England
Town: Ipswich
Boat name: Click and Collect
Make: Valiant and Narwhal
Length: 4m +
Engine: Outboard
Join Date: Sep 2016
Posts: 1,030
Quote:
Originally Posted by The Gurnard View Post
I am no expert Big Plumbs but would imagine the impeller is like everything..if you dont use the boat much..it will last for years. I do my own servicing and check my impellers every winter but only replace them when I think they require replacing.

Example my 6HP Yamaha Four stroke averages around 200 hours per year. I check the impeller every winter and decided to change it after three years of use..approx 600 hours of running. It was still in reasonable conditions but the ends of the blades were wearing flat and it was starting to loose its spring feeling when I bent them..if that makes sense.

So yes..you are correct they could be fine..but if it was my OB ..I would at least check their condition. Simply because if they fail at sea..(and you have no idea what shape they are in ?) ..they could cause a loss of life. If not yours or your brothers ..someone elses if the RNLI are attending to your problem and someone else gets into serious trouble. Admittedly .. very unlikely .. but not something I could live with if it happened to me .. simply because I ignored checking a vital part of the engine that does wear out.

Does my reply make you think ?

PS..I don't replace my plugs every year either..I keep them going until I think they are done..but I check them regular too ..and carry a spare set on the boat

Very wise words. I wonder however about the old adage if it ain't broke don't fix it


Or as I have herd it...... if it ain't broke don't break it
__________________
Bigplumbs is offline   Reply With Quote
Old 08 August 2019, 17:06   #7
Member
 
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,489
Quote:
Originally Posted by Bigplumbs View Post
Very wise words. I wonder however about the old adage if it ain't broke don't fix it


Or as I have herd it...... if it ain't broke don't break it
Do you change oil in your car?
What about timing belts?
__________________
ShinyShoe is offline   Reply With Quote
Old 08 August 2019, 17:09   #8
Member
 
Country: UK - England
Town: East Anglia
Boat name: Nimrod II
Make: Aerotec 380
Length: 3m +
Engine: Yamaha 15Hp 2-stroke
Join Date: Nov 2007
Posts: 4,861
I'm always a bit nervous with any used new to me outboard re the impeller condition even if it pumps OK so as part of getting the outboard to a known position I'll change it using a genuine OE one. With the Yamaha 15 2-stroke I bought this year I put in the full kit with upper pump housing liner and lower plate so it starts off as new.

Now I've done this, with our low leisure use hours compared to Gurnard, I'll probably only drop the lower unit 2 yearly and replace the impeller then whatever the condition. For me it's not worth the trouble of just inspecting at such an interval but then leaving the old one in.
__________________
Fenlander is offline   Reply With Quote
Old 08 August 2019, 18:13   #9
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,973
Quote:
Originally Posted by gpsguru View Post
At 6 years you really need to have a good inspection for the rubber cracking at the root of the vanes ...........

If those leg bolts have been sitting for over 6 years I’d be keen to check they will actually move when needed.

BP presumably your inlet has a “grill” on it to filter out the big bits that won’t make it through the passages. There is no guarantee the bits that break off will be small enough to cause you no problem.

FWIW - I don’t religiously change impellers annually. I actually think many people don’t. But with an engine of that age having been sitting doing nothing for a long time - I wonder why you would take the risk.
__________________
Poly is offline   Reply With Quote
Old 09 August 2019, 00:17   #10
Member
 
Country: UK - England
Town: Ipswich
Boat name: Click and Collect
Make: Valiant and Narwhal
Length: 4m +
Engine: Outboard
Join Date: Sep 2016
Posts: 1,030
Quote:
Originally Posted by Poly View Post
If those leg bolts have been sitting for over 6 years I’d be keen to check they will actually move when needed.

BP presumably your inlet has a “grill” on it to filter out the big bits that won’t make it through the passages. There is no guarantee the bits that break off will be small enough to cause you no problem.

FWIW - I don’t religiously change impellers annually. I actually think many people don’t. But with an engine of that age having been sitting doing nothing for a long time - I wonder why you would take the risk.
Because it is pumping water very well and changing it is unnecessary.

Why would you do something that does not need doing why would you take the risk of messing something up when you pull it to pieces. Always a risk

There is theory and then their is facts and the evidence you see

If you have 10 boats + to look after and 12 engines you tend to only do what is necessary
__________________

__________________
Bigplumbs is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 19:14.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.