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Admiral
Posts: 1140
Home Port: Seattle
IP Logged | Capt Pete,
that is very interesting. I noticed in taking the pump apart that the circlip was "recessed" which is strange. Normally a circlip rests against a non moving part so there would be no need to machine a recess/ hence there should be no groove. If I get where you are coming from then the washer is spining, creating a groove, hence taking pressure off the seal which causes it to leak? |
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Admiral
Posts: 437
Home Port: New Zealand
IP Logged | A circlip aways sits in a groove. You are correct in that a circlip sits against a stationary part. (You can have an external circlip or an internal circlip, one is smooth on the outside, and so goes into a hole, the other is smooth on the inside and so goes on a shaft).
The circlip holds tension against a washer against the seal. One half of the seal is pressed into the housing, the other half is tight on the shaft. The circlip holds the half on the shaft in place so the preload on the carbon faces is correct.
The theory on the failure of these pumps is that the two carbon faces stick together, and then the shaft half of the seal spins on the shaft, flogging out the center of the seal so the water leaks along the shaft. It also spins the washer and circlip, flogging out the circlip groove, wrecking the shaft.
If you look at the pix, there is a picture of the shaft half of the seal, the washer and the circlip, and the washer is obviously trashed.
Regards Pete
Edited by Capt Pete 6/25/2010 7:49 AM
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Admiral
Posts: 1140
Home Port: Seattle
IP Logged | I wrote it kinda wrong. Of course the circlip sits in a groove on the shaft. I was just surprised at the groove in the washer it sits against and that a carbon seal would stick hard enough to make it spin like that. I wonder if a harder material on the washer would make it last a little longer noting at least on mine the circlip was undamaged and had little if any wear. |
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Admiral
Posts: 437
Home Port: New Zealand
IP Logged | The circlip often looks fine and would be reusable (They are cheap so I do not know why you would want to reuse it as a new one comes in the kit). But the circlip groove on the shaft needs to be carefully inspected. That is what gets damaged.
Regards Pete |
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Deck Hand
Posts: 5
Home Port: Hampton, VA
IP Logged | My Sherwood pump went out at 248 hours. Cummins offered a rebuild kit for $600 plus labor, or a new pump for $1,100 plus alot less labor and 1 year warranty. I had them install the new pump. A easy as y'all make it sound, I'm not up to rebuilding the old one. Does anybody know where I can send it? |
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