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  Topic Review (Newest First)
2 Days Ago 05:01 PM
LinekinBayCD
Re: Premature impeller failure cause

Quote:
Originally Posted by hellosailor View Post
Engine running at 190F? Did I miss something, or is this a fresh water (or heat exchanger?) boat?

In salt water, if you run over ~150F you will get minerals crystalizing out of the salt water and blocking the engine cooling passages if you are raw water cooled.

FWIW.
Heat exchanger.
2 Days Ago 04:59 PM
LinekinBayCD
Re: Premature impeller failure cause

Quote:
Originally Posted by celenoglu View Post
The impeller is designed to work at higer pressures than it is rated, therefore the dimensions of the pipes and hoses are not the reason. The problem is the impeller. The batches might be faulty (Bad luck). If you face the same problem again it is best to drill a hole through the rubber to the bushing and put a short bolt which is not too much higher than the rubber.
Don't think it is bad impeller batches. The impellers that failed were from multiple sources both Westerbeke and Johnson branded and bought over multiple years or provided by Westerbeke / Hansen Marine over multiple years.

The impellers have a pin that fits in a slot in the pump to drive it. I believe they extend in to the rubber a little.
2 Days Ago 04:50 PM
LinekinBayCD
Re: Premature impeller failure cause

Quote:
Originally Posted by boatpoker View Post
I have the sam engine. I'd love to see some photos of your mods.
PM me with your email address and I'll email you some pix. Might be quicker than me getting around to posting the pix here.
2 Days Ago 03:07 PM
hellosailor
Re: Premature impeller failure cause

Engine running at 190F? Did I miss something, or is this a fresh water (or heat exchanger?) boat?

In salt water, if you run over ~150F you will get minerals crystalizing out of the salt water and blocking the engine cooling passages if you are raw water cooled.

FWIW.
2 Days Ago 02:55 PM
celenoglu
Re: Premature impeller failure cause

The impeller is designed to work at higer pressures than it is rated, therefore the dimensions of the pipes and hoses are not the reason. The problem is the impeller. The batches might be faulty (Bad luck). If you face the same problem again it is best to drill a hole through the rubber to the bushing and put a short bolt which is not too much higher than the rubber.
2 Days Ago 02:51 PM
boatpoker
Re: Premature impeller failure cause

Quote:
Originally Posted by LinekinBayCD View Post
Fast forward to 2015. After another impeller failure in the summer of 2014 on my Westerbeke 55 I had enough of trying to investigate the cause of the annual failures. I bought a new pump, upgrading from the stock Johnson belt driven F35 to a Johnson F5 crank mount. My yard had an adapter plate fabricated so that the pump could be bolted the adapter plate which in turn was bolted to the crank pulley. The crank mounted pump has the added advantages of eliminating a belt and being 1000% more accessible for changing the impeller. Previously the pump had to be removed in order to change the impeller.
I have the sam engine. I'd love to see some photos of your mods.
2 Days Ago 02:40 PM
sony2000
Re: Premature impeller failure cause

I noticed on the Atomic 4 pumps that it was easy to end up with an impeller that is a little too wide for the casing, as well as too narrow. The cams wear down over time, and may even wear out the blades, if they have been damaged.
2 Days Ago 02:18 PM
LinekinBayCD
Re: Premature impeller failure cause

Fast forward to 2015. After another impeller failure in the summer of 2014 on my Westerbeke 55 I had enough of trying to investigate the cause of the annual failures. I bought a new pump, upgrading from the stock Johnson belt driven F35 to a Johnson F5 crank mount. My yard had an adapter plate fabricated so that the pump could be bolted the adapter plate which in turn was bolted to the crank pulley. The crank mounted pump has the added advantages of eliminating a belt and being 1000% more accessible for changing the impeller. Previously the pump had to be removed in order to change the impeller.

I sized the new pump so that it pumps roughly 1.5 time the GPH as the stock pump. Because of the size the difference between the crank pulley and the pulley attached to the pump, the water pump was spinning at 125% the engine RPM's. During the course of investigating what pump to use I learned that by changing the size of the cam in the pump the GPH can be increased or decreased. Although the new F5 pump probably pumps 2.5 times the GPH of the F35 at any given RPM I got it down to about 1.5 times (150%) the old GPH by using a different cam and the slower RPM due to being mounted on the crank.

The water flow is noticeably greater but not crazy more than with the old pump. The engine is running slightly cooler which is a good thing as it sometime would be over 190 degrees. Now seems to settle in at about 182-183 at cruising RPM's. If I make it through the summer without an impeller failure I'll know if this remedy was a success. At least now changing the impeller will be a 10 minute job.
07-28-2013 10:10 AM
aa3jy
Re: Premature impeller failure cause

Couple of things after reading this post... Check to see if new impeller doesn't delaminate by trying to pull the vanes at the 9 o'clock and 3o'clock position.

Flip the water pump cover and try the unused side.

Make sure the impeller has seated it self fully on the shaft.

Too much pressure from the cover on a improperly mounted impeller may cause excessive heat which in turn may cause premature failure..
07-28-2013 08:38 AM
Mechsmith
Re: Premature impeller failure cause

In my 7.5 Merc. 2 stroke the impeller failed after being test run in a 50 gallon barrel. The first time after being prepped by a repair shop, The second time I did it all by myself. The impeller aparently cannot stand the oil in the exaust. Now I always keep a spare impeller and the tools. They were both OE impellers.
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