Changing A Raw Water Impeller (How To) - Page 3 - SailNet Community
 3Likes
Reply
 
LinkBack Thread Tools
post #21 of 43 Old 07-28-2008 Thread Starter
Senior Member
 
Maine Sail's Avatar
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,826
Thanks: 19
Thanked 213 Times in 162 Posts
Rep Power: 16
       
Quote:
Originally Posted by LittleWingCA View Post
Something worth considering, since you can't always predict when the impeller will go bad, and chances are it is when you really want to have the engine working.
As I stated in my article if you replace your impeller annually, and don't run it with limited flow or dry, you should almost never have an impeller failure.

I have been replacing impellers annually and this is the first cracked blade I've had in 12 years and it was because I let it run knowingly with limited flow.

In twelve years of annual impeller replacements not once have I needed to change an impeller at sea or mid season due to failure. This is the first one and I killed it knowingly..

I would have never needed to replace this one if I didn't have a baby with a sleep schedule on board (actually, it's our sleep schedule and if she gets off hers I don't get any) and I had stopped for 5 minutes to clean the sea strainer.

Spare pump is a good idea. I carry one, yet to use it, and a re-build kit..

______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.



Last edited by Maine Sail; 07-28-2008 at 11:11 PM.
Maine Sail is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #22 of 43 Old 07-29-2008
tdw
Super Fuzzy Moderator
 
tdw's Avatar
 
Join Date: Oct 2006
Location: Sydney Australia
Posts: 16,390
Thanks: 15
Thanked 103 Times in 97 Posts
Rep Power: 10
     
I saw recently something referred to as a quick change impellor cover. Didn't take a lot of interest in it as our Bukh is a easy as can be to change. Yanmars can be a bugger so I wondered if these things were of any use.

As per usual thanks to H for original post. I'm a believer in his principle of change once a year whether needed or not. After the first and only time I had an impeller fail and I didn't have a spare I've changed religiously every year and only bother I've had was from a bloody plastic bag.

Also do the same with belts. It's not a huge expense and the peace of mind makes it all worthwhile. (and you end up with lots of spare belts and impellers, lots and lots.)

Andrew B

“Life is a trick, and you get one chance to learn it.”
― Terry Pratchett, Nation

Malo 39 Classic
tdw is offline  
Quote Quick Reply Share with Facebook
post #23 of 43 Old 07-29-2008
moderate?
 
camaraderie's Avatar
 
Join Date: May 2002
Location: East Coast
Posts: 13,877
Thanks: 0
Thanked 3 Times in 3 Posts
Rep Power: 16
     
Fuzzy...I think you are referring to speedseal.com
bvander66 likes this.

No longer posting. Reach me by PM!
camaraderie is offline  
Quote Quick Reply Share with Facebook
post #24 of 43 Old 07-30-2008
Junior Member
 
Join Date: Jun 2006
Posts: 18
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
 
Greetings,well this JH4 has had a cooling prob since it's refit in Cartegena,lucky me,4th mechanic to get involved, figure out why no flow out the Exhaust.
short version,replumbed bad strainer routing,all the way back to the pump and disected pump to find the Backing plate missing! Probably in the deep bilge with
many other parts,tools and sunglasses. this isn't a common replacement part.
Got it shipped in and now it flows like mad and runs very cool.too bad it smokes blue,overheated too many times... Lesson, Assume nothing! Cheers
crzhors is offline  
Quote Quick Reply Share with Facebook
post #25 of 43 Old 07-31-2008
Senior Member
 
Join Date: Jun 2007
Posts: 2,708
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 10
   
Quote:
Originally Posted by halekai36 View Post
As I stated in my article if you replace your impeller annually, and don't run it with limited flow or dry, you should almost never have an impeller failure.

I have been replacing impellers annually and this is the first cracked blade I've had in 12 years and it was because I let it run knowingly with limited flow.
I still find this disturbing, Hal. I can't find your comments on the incident atm, but, IIRC, you let it run with mildly restricted flow for a short while. ISTM an impeller designed for this application should be able to tolerate that. What brand was the failing impeller?

I know you have had poor results with Globe's blue "run-dry" impellers, and I have found others who have experienced similar failures: Where the hub breaks free of the surrounding material, so the vanes no longer turn. But I notice that some Globe impellers appear to have non-metalic hubs and some metal. One of the failed ones about which I read was reported to have a "plastic" hub. I wonder which yours was and, if it was non-metalic, if the Globe impellers with metal hubs are better?

Did you try to contact Globe about this early failure? I certainly would have. Tho I note that, in a couple of the articles I found, it was reported Globe was unresponsive to complaints about this product. I find that disquieting.

Jim
SEMIJim is offline  
Quote Quick Reply Share with Facebook
post #26 of 43 Old 07-31-2008
Senior Member
 
timebandit's Avatar
 
Join Date: Sep 2002
Posts: 928
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 13
 
Just to add a few more tips.

Don't be a silicone junkie. If you clean off the old gasket as recommended you shouldn't need a sealer.

An old product called "Gasket Cinch" will keep the gasket attached to the cover while you are trying to get it on. Gasket cinch is aplied like contact cement, coat the cover(always attach the gasket to the removable part) and the side of the gasket that attaches to it and allow to dry and then using a couple of screws to aling the gasket just press. Gasket cinch is a low stick kinna stuff and will allow the gasket to be removed later with little effort.

Now you have the plate with the gasket attached just reach for your tub of BTG (Boat Trailer Grease). Go ahead, get a little on your finger and rub on the side of the gasket that goes to the housing.

BEWARE of rubbing grease on the housing as it might have a sharp edge.

As most mechanics know--If you put the first bolt in at the 12 o'clock position the cover will almost swing into place. Remember to always start all bolts before tightening any and then in a criscross pattern.

The next time you have to change the impeller the gasket will come off with the cover and be easy to remove and clean up will be a snap.

If that day comes when you have to change the thing in a hurry just pull the cover change the impeller and use the old gasket and you should be done in about 5 min.

If of course you have one that is easy to get to

Rick
timebandit is offline  
Quote Quick Reply Share with Facebook
post #27 of 43 Old 07-31-2008 Thread Starter
Senior Member
 
Maine Sail's Avatar
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,826
Thanks: 19
Thanked 213 Times in 162 Posts
Rep Power: 16
       
Quote:
Originally Posted by SEMIJim View Post
I still find this disturbing, Hal. I can't find your comments on the incident atm, but, IIRC, you let it run with mildly restricted flow for a short while. ISTM an impeller designed for this application should be able to tolerate that. What brand was the failing impeller?

I know you have had poor results with Globe's blue "run-dry" impellers, and I have found others who have experienced similar failures: Where the hub breaks free of the surrounding material, so the vanes no longer turn. But I notice that some Globe impellers appear to have non-metalic hubs and some metal. One of the failed ones about which I read was reported to have a "plastic" hub. I wonder which yours was and, if it was non-metalic, if the Globe impellers with metal hubs are better?

Did you try to contact Globe about this early failure? I certainly would have. Tho I note that, in a couple of the articles I found, it was reported Globe was unresponsive to complaints about this product. I find that disquieting.

Jim
I got nowhere with Globe and if I remember correctly it was a metal hub.

My current thinking is that my Johnson impeller was an old one when I installed it. My baot came with two new spares but who knows how "old" they were. Johnson has since changed the rubber compound to a product called MC97 which is supposed to be better.

Limited flow can be enough to heat up the impeller but still enough to not over heat for a while. I have actually measured my raw water pump before (not on this boat) with my infrared under a "partial flow" and it was over 200 degrees..

The only lubrication is water and you have rubber on bronze spinning at a high rate of speed. Lose flow and you have less lubrication and cooling.

I've had this happen before and never seen cracks so my only guess is that the impeller was many years old and the rubber was aging before I actually installed it? That is my best guess because my engine had only climbed to about 190 and I was still getting a "mist" out my exhaust. If you've experienced a partial blockage you'll know what I mean by mist..

After this incident I bought 3 new impellers all with the new MC97 compound and threw away my one year old used ones. At $16.00 for an impeller why risk it..

______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Maine Sail is offline  
Quote Quick Reply Share with Facebook
post #28 of 43 Old 07-31-2008
Senior Member
 
Join Date: Jun 2007
Posts: 2,708
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 10
   
Quote:
Originally Posted by halekai36 View Post
I got nowhere with Globe...
Yours would be the third incident I've read of where somebody had premature failure of a Globe RunDry [tm] impeller and got no satisfaction from Globe Composite Solutions, Ltd. That's enough for me. Any company can have product failures, but I expect vendors and manufacturers to stand by their products.

Quote:
Originally Posted by halekai36 View Post
...and if I remember correctly it was a metal hub.
So much for that theory

Quote:
Originally Posted by halekai36 View Post
My current thinking is that my Johnson impeller was an old one when I installed it. My baot came with two new spares but who knows how "old" they were.
...
I've had this happen before and never seen cracks so my only guess is that the impeller was many years old and the rubber was aging before I actually installed it?
That would certainly explain it!

Quote:
Originally Posted by halekai36 View Post
After this incident I bought 3 new impellers all with the new MC97 compound and threw away my one year old used ones. At $16.00 for an impeller why risk it..
Indeed! I'll buy two and install one this season. Next season I'll install the other and order a new spare. Each season: Wash, rinse, repeat.

How can you tell if Johnson impellers are fabricated with their new MC97 compound?

Jim
SEMIJim is offline  
Quote Quick Reply Share with Facebook
post #29 of 43 Old 07-31-2008 Thread Starter
Senior Member
 
Maine Sail's Avatar
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,826
Thanks: 19
Thanked 213 Times in 162 Posts
Rep Power: 16
       
Quote:
Originally Posted by SEMIJim View Post

How can you tell if Johnson impellers are fabricated with their new MC97 compound?

Jim
Like this..


______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Maine Sail is offline  
Quote Quick Reply Share with Facebook
post #30 of 43 Old 07-31-2008
tdw
Super Fuzzy Moderator
 
tdw's Avatar
 
Join Date: Oct 2006
Location: Sydney Australia
Posts: 16,390
Thanks: 15
Thanked 103 Times in 97 Posts
Rep Power: 10
     
Quote:
Originally Posted by camaraderie View Post
Fuzzy...I think you are referring to speedseal.com
That's the thing. Looks to me as if the only change is using gnurled knob instead of slotted screws. Not a bad idea I must admit but hardly revolutionary.

Any thoughts ?

Andrew B

“Life is a trick, and you get one chance to learn it.”
― Terry Pratchett, Nation

Malo 39 Classic
tdw is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
raw water anti siphon/vented loop? deniseO30 Gear & Maintenance 16 05-28-2008 11:12 AM
Raw water pump bestfriend Gear & Maintenance 56 04-26-2007 09:03 AM
Gifts from the Rain Gods Doreen Gounard Cruising Articles 0 03-18-2004 07:00 PM
leak from engine raw water siphon break i670684 Gear & Maintenance 2 08-11-2003 05:53 AM
Raw Water in Engine wmwtlw Gear & Maintenance 3 02-25-2001 11:31 AM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome