Raw water pump drip

[Safran]

I have a drip from the aft seal on my Perkins 4.108 raw water pump, about 1 drip every 3 seconds. The seals round the shaft are evidently going, with the possibility of shaft wear.

The question is, how quickly is this likely to get worse? Should I replace the seals/shaft immediately or can I safely leave it for 100/200/500 hours? Would appreciate opinions as to how long I can safely leave it.

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[cliff]

Difficult to say, I have had seals go completely in less than half an hour on the otherhand I've known seals to leak for hours before finally giving up the ghost.
If it was my boat I would change the seals as soon as possible or change the pump which might be cheaper in the long run if the shaft is damaged.
Have you checked the bearings (bushes) If these are worn you will wear out the seals quicker than normal.

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[freebird1]

Almost certainly going to be shaft wear as well. I'd change it sooner than later, before water starts find it's way down the shaft and into the engine.

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[LeytonC]

Change the seals, its quite a simple job. I had to do both of mine. It might also be worth replacing all the wear plates and cam at the same time. My pumps now work like brand new!

MBM ran an article as while back (sorry, cant be more specific at the moment) on how to do this.

1 word of warning, make sure the drive of the pump fits EXACTLY in to the drive dog on the fuel pump gear as they are very slightly different sizes (this is not obvious) If you dont you will bend the pump shaft.

The shaft of the pump is only held in the drive dog / bearing assembly by friction so if the shaft of the pump is worn by the water seal at the back of the pump it is possible to move the shaft forward by 0.25" by hitting it hard. (if you break it, its not my fault /forums/images/icons/laugh.gif) so the seal is on good metal - This is a get you home measure only, replace the shaft or get it welded ASAP.



<hr width=100% size=1>Thanks

Leyton
(EXTAR Solutions - Software that works for you)

 

[TonyBrooks]

I have a feeling that if this is a heat exchanger engine the pump has a ball bearing or two in it. If I am right, I would advise removing the pump, changing the seals, possibly the shaft, and the bearings asap. If thew ater gets to a ball bearing and it rusts or breaks up, the failure could be quick and almost total.

Tony Brooks

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[brianhumber]

An age old trick to get you out of trouble if you have no spares.

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[Safran]

Thanks very much to all.

Will replace the pump as soon as the new one just ordered arrives and rebuild the present one as a spare - sounds as though I will probably have to have the shaft built back up.

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