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Old 06-29-2018, 11:19 AM   #21
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Removed the pump. Impeller did not disintegrate into pieces, the rubber still flexes and no cracks, but when measured it is worn on its side which is why it lost prime. 0.736 is what it measures and it is supposed to be 0.75.
I was able to suck on the input line it flowed well, boy that was nasty, it got in my nose too.

I think a simple small AC electric water pump could work. What is the pumping losses of an impeller vs the electrical cost of centrifugal pump? I can mount it low enough to work.

Still plan to split open the drive end for the new impeller.
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Old 06-29-2018, 12:22 PM   #22
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Originally Posted by Xsbank View Post
This is not rocket science. There is a simpler solution. That sea-water circuit will kill your engine somewhere you don't want to be at exactly the wrong time. Change the impeller EVERY year. That's it. If you use your engine more than the average, then change it every twice a year. Its a piece of rubber that spins billions of times inside a metal housing - what is fundamentally wrong with that concept?


That is my thought. Iíve never replaced an impeller that had missing pieces off the blades. Maybe because Iíve always replaced the impellers yearly?
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Old 06-29-2018, 12:31 PM   #23
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I will give credit to Globe impellers, I have been using 2 for 2 different pumps and neither has disintegrated yet, although they wear the edges down, which is to be expected.
Another good reason to change them out.
I bought this globe impeller in October 2013, so now is 2018, almost 5 years of use! I checked my email to find out the date. Of course not continuous usage of the gen. I do not keep a record of hours, but might average a couple hours per week for about 4 years.

I used my dremel to slice down a slot in the 316 SS pump shaft, and it went fast. Kept it cool by dipping in water. The wheel is too small to finish, so I used my handheld jigsaw blade to finish the slot. When the new impeller arrives, I will spread open the slot and fit it properly parallel to the bore of the impeller.

The whole thing seems very easy so far. It ought to actually be about a perfect fit when I am done.

Behind this is a ceramic seal disc and rubber washer. Since its diameter is much bigger than the drive shaft, it will fit fine over the expanded drive shaft. A C clip secures rubber disc and ceramic seal washer to the shaft, and it fits into the ring slot cut in the shaft.

My plan is to slam a piece of steel down the slot the width of the pin in the impeller, then bend the ears in parallel to fit the bore. Since I am going from 5/16 to 3/8, this ought to be just about perfect.
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Old 07-01-2018, 01:21 PM   #24
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Quote:
Originally Posted by FF View Post
"I have 2 of those Sendure inline strainers before the pumps."

Before the pump filters only water entering the pump

After the pump catches even tiny bits of impeller.

When an impeller sheds its vanes, the debris are forced into the pumps gratings by the remaining vanes, and though you might think that would be only on the downstream side of the pump, it can happen on the intake side too.
These will lurk between the pump and he strainer, often only blocking the pump inlet when the motor is revved up.
So a wye strainer on both sides of the pump is not too far fetched, for those that refuse to install a new impeller annually.
Two of them before the pump might have been an attempt to sidestep an intake strainer.
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Old 07-02-2018, 03:35 PM   #25
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I burned an impeller in my 1989 Ford Lehman engine. As I recall I sucked up a plastic bag, over heated, and before I knew it, destroyed the impeller. Now looking back, maybe it overheated because the impeller exploded. Took a few hours climbing over this stb engine to extract what I could from the pump body, then dismantle all of the hoses to get out the bits. Also, the heat exchanger zinc was toast (this may have been a different event). When I cleaned it up I used bamboo skewer sticks to clean out the tubes. Also, I only bought the factory zincs once. Then I bought zincs online for a fraction of the cost and cut 1/2" off so they would fit right. Engine ran cool after that.
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Old 07-02-2018, 07:18 PM   #26
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Why are you using zinc anodes in freshwater and not magnesium?
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Old 07-02-2018, 11:49 PM   #27
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Hi from across the Atlantic in Guernsey, Channel Islands.

I remove, check and replace if necessary, the impellors on our two Cummins and two Onans every year. It's far too much hassle to find the bits if one breaks. I buy replacements from Cummins (and in the UK, Onan parts come from Cummins) just to make sure I'm not buying sub-standard copies.

I also carry complete replacement pumps which are far easier to replace than impellors at sea if something goes wrong.

And for zincs, yes, changed every 6 months if the boat is not used, and every 3 months if we're cruising.

I you have a limescale build up in the engine, I used this method to de-scale: Descaling the heat exchanger | Play d'eau

All the best - GPB
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Old 07-03-2018, 02:41 PM   #28
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I successfully modified the pump shaft to take the pin drive impeller style.
I am not familiar with the Jabsco 4528 impeller design, does the SS pin simply push into the impeller, or screw in?

On this one, it simply is held by the rubber, not threaded into the brass. I was wondering what would happen if the pin worked out, would be bad. I used some instant glue and secured the pin to the impeller.

Perfect fit to the pump and shaft now. the pin is quite a bit wider that I thought.
And if your going to press this apart, don't press on those ears, press on the bottom of the slot. Quite possible those smaller ears could bend now. Or have a collared adapter to slide over the shaft when pressing it out.

I actually have a backup original pump in case this mod fails, but it wont fail. This is how they work.
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Old 07-03-2018, 04:53 PM   #29
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Its hard to see for sure but is that a threaded "pin" in there? I would have assumed the impeller came with the pin in place. Either way, I wouldn't feel comfortable relying on glue to hold the pin in. Next time, I would would suggest using something like a spring pin (sometimes called a roll pin) that has a bit of a press fit in the impeller.

Ok I looked it up and I'm a bit surprised how they do it. It looks like a set screw to me. Next time I would suggest using red loctite on the screw threads. Or perhaps "buggering" the threads with a pair of pliers or something so it is a bit hard to screw in which should keep it from backing out. Or maybe the action of the drive shaft on the "pin" buggers the threads and keeps it from backing out? Obviously, it must work.

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Old 07-04-2018, 06:42 AM   #30
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Its hard to see for sure but is that a threaded "pin" in there? I would have assumed the impeller came with the pin in place. Either way, I wouldn't feel comfortable relying on glue to hold the pin in. Next time, I would would suggest using something like a spring pin (sometimes called a roll pin) that has a bit of a press fit in the impeller.

Ok I looked it up and I'm a bit surprised how they do it. It looks like a set screw to me. Next time I would suggest using red loctite on the screw threads. Or perhaps "buggering" the threads with a pair of pliers or something so it is a bit hard to screw in which should keep it from backing out. Or maybe the action of the drive shaft on the "pin" buggers the threads and keeps it from backing out? Obviously, it must work.

Ken
It must work because most people would just put it in without thinking.
I also got a close up picture of a genuine jabsco, and it shows no threads, just slides in. The rubber must be sufficient to hold the pin in place.

https://www.amazon.com/Jabsco-4258-0.../dp/B077QDNJQJ

I ordered another exact same one for less at $3.96
It feels like good quality rubber on this impeller.
https://www.aliexpress.com/item/Impe...714701567.html

Loctite would help it stay in place. but got to make sure does not overflow which would interfere with being able to slide it onto the shaft. The small amount of instant glue, I had t scrape off the inside of the impeller bore for it to again smoothly slide on.

I also thought you might be able to expand the ends like a rivet by hitting it with a drift, but the might slightly bend the pin, then it wont slide on.

This impeller is also used on some shafts where is just a pin hole not a slot.

This SS pin is actually a long set screw, so you can turn it with an angle wrench.

I really like switching away from a design that is going to have fewer future buyers and parts selling like gold, saw one seller selling a genuine Onan impeller for $103, which is crazy.
And nice to get these so cheap now.
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Old 07-05-2018, 12:07 PM   #31
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I purchased one of these http://www.speedseal.com/SpeedsealLi...howitworks.htm but haven't gotten to the boat yet to install it. My Deere 4045 main engine uses a generic Johnson F7B-9 raw water pump. A little more run-dry capability, and easy-change pump cover. That and a Globe Run-Dry Impeller might be too much upgrade in one go--hopefully they'll turn out to be good upgrades which will lessen the chances of impeller destruction.
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Old 07-05-2018, 05:20 PM   #32
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I have yet to see a GLobe impeller disintegrate into pieces.

Back to my mod, a total success. We were out on the water for 5 hours today and ran the gen the whole time. It pumped perfectly.
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Old 07-05-2018, 05:29 PM   #33
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Originally Posted by Wil View Post
I purchased one of these http://www.speedseal.com/SpeedsealLi...howitworks.htm but haven't gotten to the boat yet to install it. My Deere 4045 main engine uses a generic Johnson F7B-9 raw water pump. A little more run-dry capability, and easy-change pump cover. That and a Globe Run-Dry Impeller might be too much upgrade in one go--hopefully they'll turn out to be good upgrades which will lessen the chances of impeller destruction.
I watched that video and think it is a good idea.
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Old 07-05-2018, 05:47 PM   #34
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Originally Posted by Wil View Post
I purchased one of these Welcome to Speedseal How it Works but haven't gotten to the boat yet to install it. My Deere 4045 main engine uses a generic Johnson F7B-9 raw water pump. A little more run-dry capability, and easy-change pump cover. That and a Globe Run-Dry Impeller might be too much upgrade in one go--hopefully they'll turn out to be good upgrades which will lessen the chances of impeller destruction.
The Speedseal website says they've gone out of business. I have the Speedseal Life and would like to get a set of the 2 wearable parts. Anybody else dealt with this?
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Old 07-05-2018, 06:14 PM   #35
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The Speedseal website says they've gone out of business. I have the Speedseal Life and would like to get a set of the 2 wearable parts. Anybody else dealt with this?
Why? Did they wear out?
You can go to a bearing supply house and buy teflon sheet in various thicknesses, just cut it to fit.
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Old 07-05-2018, 07:37 PM   #36
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Unfortunate--didn't realize this happened, bought mine 6-8 mos ago. Hopefully someone will continue the business.
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