Nanni 4150HE - replacing raw water pump bearings

[KompetentKrew]

Hello all,

Some time ago a mechanic was onboard - he reported that there was play in the impeller shaft, and that the bearings need to be replaced.

This job is now well due, but I've never worked on this part of the engine before and I'm not sure exactly what the job involves.

The pump is shown on page 22 of the spare parts catalogue [PDF], and I've circled the bearings:

This pump appears to be made by Johnson - according to this PDF, both Nanni and Beta fit the same pump when marinising this engine, part number 10-24334-01.

Assuming that is correct, this PDF tells me the pump is also known as a "F5B -9", and gives me part numbers for the service kit and various seals, gaskets, etc.

Bearings: UK / EU

Does this all seem right so far, please?

What other parts do I need? I guess the washer (16), o-ring (14) and seal (13) should be replaced during the rebuild? Anything else?

It looks like I can just take the whole pump off the front of the engine and rebuild it on the table of the salon.

I would be grateful for any other advice or pointers.

 

[Lucy52]

I have a 3.100HE and when searching around for pump parts I found a replacement pump was available for approximately £150. The previous owner had replaced it once and had been able to get one. I also searched using the Kabota base engine details. Here is a web site with pumps for sale.

Cooling Pumps - COOLING PUMPS AND SPARES

You could fit a new pump and refurbish the old one as a spare. You seem to be on the right lines as far as it goes, Now found the web sites I used:

SPX Johnson Pump: Flexible impeller pumps spare parts - buy online, Page 4

for example:

SPX Johnson Pump 0.3431.761 Ball bearing (05-08-123) - buy online

They were helpful if you email them with the part you need, they seem to have a full range of spares. There must be a UK site with spares as well.

 

[KompetentKrew]

A complete replacement pump is €280 on that site, whereas the bearings are remarkably cheap - less than a tenner each.

A service kit, which seems to contain everything but the bearings, is £55 / €61

So repairing this one is definitely order of the day.

The impeller itself seems in good condition, but I assume it is considered best practice to replace these at any reasonable opportunity?

It's not clear to me whether an impeller failure will lead to disaster.

 

[Lucy52]

If the impeller breaks up then the bits will travel to the heat exchanger where they may block the tubes. With less water being pumped by the broken impeller and an obstructed heat exchanger then the engine is likely to overheat. Whether that is a disaster or not will depend on how soon you realise it and the circumstances you find yourself in. It will of course seize up if you ignore it or at least gouge the cylinders for you if you don't stop the engine. Best avoided if possible.