Rule Bilge Pump Failure


Is there any magic in a Rule Bilge pump? Will it last forever? Can you stake your life and your boat on it? I wouldn’t stake my life and boat on any single company, product or part. You need both quality and redundancy.

I had the opportunity to take apart a bilge pump that had failed. I love doing this because it tells me what is good and bad about product and what to watch out for. This bilge pump was a Rule 1500 GPH pump and came out of a 1967 Bertram 25. A very nice boat and a very good pump. The pump was old (STAMPED 649)  but probably not as old as the boat (my guess is  20 years old). So what was the issue.

rule bilge pump 004

As you can see there is rust inside the pump where water had gotten into it.  The brushes were worn but they still had much life in them but one of the connections was frayed as you can see from the following picture. While this is a potential problem it still is not what caused the failure.

spring 2013 141

The pump has a stainless steel shaft and bronze bearings in good condition. The following picture shows the armature is rusted and was covered in grease. Where did the grease come from? Probably the bilge water was oily and infiltrated the casing through a failed waterproof seal.

spring 2013 armature

It sports permanent magnets for added reliability and were in good but a little rusted.

spring 2013 magnets

Waterproofing was accomplished via an  o-ring and wire through hull fitting. I can’t really tell which failed but I suspect the wire. If there was any real pressure I don’t think the wire waterproofing would hold up. The boat was in lake water for the last 10 years so a little water in the pump by itself would not cause the failure. I’ve seen DC motors run flooded with fresh water. The corrosion would eventually cause a problem but I don’t think that was the ultimate issue with this pump.

spring 2013 148 waterproofing

The other way water can get in is through the bottom bearing. There is a seal on the SS shaft and it might or might not have failed.

Bottom Line

It was a quality brand name product. Brushes were good but connections were frayed, armature and magnets were good but rusted, bearing and seals were good but water had infiltrated.  I understand that Rule uses a triple seal which is very good for keeping out the water but not infallible. None of these issues caused the failure directly. Failure was caused by a seized shaft due to gunk on either the bottom shaft bearing or shaft seals.  Seizure was not complete but enough that the motor could not overcome it. Before I took it apart I tried to revive the pump by manually turning the shaft many times.

The main point is that “Equipment Fails”. You cannot rely on your equipment alone. You must test, analyze and create your own fault tolerant system using monitoring and redundancy as well as quality. Look around on this website to read about how you can create robustness.

Test your bilge system today then come up with a system that cannot fail with a single point of failure.

 

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