Impeller Failure

[Jeff Lewis]

Both impellers failed on my Cummins 6BTA5.9s after 75 hours. I’ve been in some shallow water and maybe ingested some sandy water, but I would still expect a little more time. The only other thing worth noting: when installing these impellers they are slightly “proud” of the housing. When you put the pump housing cover back on it is tight against the impeller. This causes the cover to get very hot on initial start up. After a “run-in” period of a couple starts and stops the housing cover stays a normal cool temperature while running. I am wondering if this initial “run-in” and hot temperatures due to the friction of the impeller against the cover may be causing the premature failure of the impellers.

Topic

[Tony Athens]

20 years in seawater? IMO, you are playing Russian roulette !

BTW, cams and inner “wear plates” corrode away with time, even when not used..

Tony

[Jeff Lewis]

Pump age

They are probably the original pumps (20 years) and will be a pain to replace. I should for your reasons, but there is no movement in the cam so I hesitate to replace. As a side, they are working great now (even after the “hot burn in” of the impellers. Great water flow, perfect cooling, and the pumps run cool to the touch.

[Jeff Lewis]

burping

The pump primed immediately (within 10 seconds), although there was air in the hose between the strainer and pump. So I need to bleed that air out? It seems hard to believe that 10 seconds dry (with a very liberal coat of grease on the impeller) would cause damage.

Any ideas about the “tight fit” of the impeller? ie. the end of the impeller is extremely tight against the pump housing cover, causing excessive friction until it is worn down

[Tony Athens]

Jeff,

How many years has this pump been operating in seawater? Sound to me, the “innards” of the pump are done—– Housing, inner wear plate, inside of the cover plate, and cam ..

As to lubing an impeller–The more lube of any type, the better. We prefer some type on GREASE.

Tony

[john]

To further the comments if you don’t see water flow almost immediately shut it down and investigate. Don’t wait until it gets hot. I’ve got about twenty of these pumps sitting around. They always leak before they wear out.

[Rob Schepis]

Jeff Lewis wrote:

What is burping the system?

Burp = Removing any air lock and getting instant prime.

Further to Justin’s comment above, I noticed a better prime with the KY vs. grease, probably because I use much more of it on the impeller and in the housing because it’s cheap and easy to work with..

[Jeff Lewis]

lubricate

Yes, I used plenty of lubrication. The pump primed quickly.

[Jeff Lewis]

pump rebuild

not sure when it was last rebuilt, if ever. The shaft is solid, with no noticeable play.

[Jeff Lewis]

Burp the system?

What is burping the system?

[Justin Riege]

Did you put the impeller in dry? Tony usually recommends using a little lubricant. Some say use a synthetic rubber safe grease, Rob likes the KY jelly, Tony says just use something, anything pretty much, once you run the engine its all going to get flushed away anyhow and fears of it degrading the impeller material are exaggerated.

A quote from tony on a previous thread

“Although the Sherwood book may say different, we have always lubed the impeller , inside of the housing, and the shaft w/ a general purpose grease just before install and use.. Most people think that degrades the impeller– It does not, but believe what you like…It makes absolutely no difference which way you twist the impeller as you push as the blades will flip over when you change directions.. Lubrication of the impeller makes for instant prime, easy install, and no dry start-ups” …………………Tony

[Philip]

Any wear inside the pump housing on the cam plates, rear wear plate etc can also cause impeller failures. Sand / silty water can cause those items to wear as well.

When was the last tim the entire pump was rebuilt vs just an impeller change?

[john]

Sounds like you burnt them up pretty good and didn’t burp the system on the initial start up. You should see no heat at any time or pre mature failure will occur.

[Author]

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