Untrustworthy Spare Impellers

Thought I'd pass along a hard-learned lesson to my fellow Ford Lehman 120 operators: Last week, as a precaution, I replaced the 3-years in service raw water impellers in both my engines. I used impellers from stores of spares that were on the boat when I bought it 4 years ago. The spares looked identical to the old impellers and had a like new appearance. Despite that, the replacement impellers failed in less than 10 hours running time. The starboard one shed all its blades, causing a brief engine overheat with attendant alarms...just as I was exiting a narrow pass out to sea. The port impeller was nearly as bad. Upon removal I noticed the failed spares were stamped with Jabsco part 1210-0003. Consulting my manual, I found the suggested impeller is a 1210-0001. Luckily I'd purchased a pair of -0001's to replenish my spares store when I did the change out last week. I noticed when I put them in that the -0001 blades felt supple and pliant. The -0003 impeller blades were stiff and almost brittle by comparison. I've now put 7 hours on the -0001 impellers. So far so good! I've been boating for quite a few years and never realized that two impellers of identical dimensions and appearance could be so different.

Captain K said:

I've been boating for quite a few years and never realized that two impellers of identical dimensions and appearance could be so different.

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For some reason I immediately thought of cats and women.

Captain K said:

I noticed when I put them in that the -0001 blades felt supple and pliant. The -0003 impeller blades were stiff and almost brittle by comparison.

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Could the spares just have been too old?

Impellers age as they sit in storage. I never install them if the box printing is faded and yellowing. Those things could have been REAL old.

Working rubber actually keeps it pliant from what I have read...so rubberized parts if not vacuum sealed are better off being worked...in other words swapped out every year or two...

As cheap as the Lehmans impellers are...2 years and swap for me....as I wouldn't trust the spares longer than that so might as well use them.

psneeld said:

Working rubber actually keeps it pliant from what I have read...so rubberized parts if not vacuum sealed are better off being worked...in other words swapped out every year or two...

As cheap as the Lehmans impellers are...2 years and swap for me....as I wouldn't trust the spares longer than that so might as well use them.

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These aren't the only impellers to be cautious about. I've known others to have issues and install spares to have immediate fails. Many impellers for many different forms of engines and equipment weaken or become brittle over time. While his was just the wrong impeller, best to keep track of the age of your spares.

Lesson: some spares can become disfunctional nearly as quickly as the parts they're intended to replace.

Jabsco suffix 0001 is neoprene, 0002 is EPDM, 0003 is nitrile, 0004 is Viton.

Both neoprene and nitrile materials have a shelf life of at least 5 years if properly stored. Both materials should be stored in a cool place, not an engine room. An ozone generator onboard would be detrimental as well. Neoprene and hydrocarbons do not play well together. Both materials can be made with similar Shore durometers so comparing flexibility probably won't tell you much unless you are comparing to new.

I've thrown away lots of O rings and gaskets in my lifetime.

Even a new raw-water pump needs inspection

Here's food for thought:

Changing the impeller on the raw-water pump of my 6.5Kw Phasor generator was today's chore - removed pump from generator, cleaned everything, applied never-seize to the shaft, slicone grease to new impeller etc. I was pleased with the way the pump rotated using a small crescent wrench on the drive dog. I have a spare (new) raw-water pump purchased some 5 years ago from Phasor at Southeastern Power and decided to give it a turn using the same small wrench. There was considerable resistance and I decided to take the cover plate off for a look. The pictures tell the tale: the pump, actualy an Oberdorfer, had been assembled totally dry and the impeller had bonded itself to the faces on the pump. It took considerable work with thinners, scotchbrite etc to clean everything up. I suspect the impeller would have failed quite quickly if the pump had been put into service the way it came out of the box.

I lesson learned the hard way - inspect the impellers when you buy them. I bought four impellers for my Yanmar engines. New in plastic bag from local dealer. When I went to install them, all four had cracks at the base of several of the vanes. I took them back before they came apart in the pump.

Northern Spy said:

Jabsco suffix 0001 is neoprene, 0002 is EPDM, 0003 is nitrile, 0004 is Viton.

Both neoprene and nitrile materials have a shelf life of at least 5 years if properly stored. Both materials should be stored in a cool place, not an engine room. An ozone generator onboard would be detrimental as well. Neoprene and hydrocarbons do not play well together. Both materials can be made with similar Shore durometers so comparing flexibility probably won't tell you much unless you are comparing to new.

I've thrown away lots of O rings and gaskets in my lifetime.

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NS is right. I use this same impeller in my Jabsco 10970 RW pump. I've switched to the nitrile/-0003 variety and have been very pleased with the service. I replace mine every 200 hrs which runs about every 2 years. My previous neoprene impellers were experiencing cracks at that interval. I have yet to find the same problems with the nitrile ones.

My standard practice is to keep one on board as a spare, so I buy 2 when it's time to replace and cycle the spare into one of the pumps. One of the new impellers becomes my new spare. I keep my spare in an area that's cool and dark in the fwd stateroom. It rarely sees the light of day. I have not seen a difference in performance between the previously stored spare and the newly purchased replacement in service.

But, of course, YMMV.

Amazing on something as expensive as our boats and equipment, how dependent we are on cheap pieces of plastic or similar materials. Well, cheap materials. Not always cheap in the form and from the supplier we need.

After three years, I'm reminded (again) to replace the engine's impeller during the next scheduled engine service this summer. So far, there is still plenty of water exiting the wet exhaust.

psneeld said:

As cheap as the Lehmans impellers are...2 years and swap for me....as I wouldn't trust the spares longer than that so might as well use them.

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I do the same. The 2 year old "spare" goes in the pump and the new one gets put in the spares box. If the one removed looks "ok" I save it in a plastic bag as a back up to the back up.

Thanks much for the info Northern Spy, and all others for the input...very helpful! Guess an old dog can learn new tricks.

Yup. . . good advice, don't store any spare parts in the engine room.

I had a two year old hydrometer (for testing the SG of batteries) stored in the engine room. Squeeze ball and rubber parts turned to crumbly powder in short order. Engine alternators plus the generators create small amounts of ozone which is harmful to rubber parts.

Good point about engine room storage. I'm going to move some of my soft spares to under a bunk.

amazing what you can learn by just being nosey!