Engine Room Discussions

[Pascal]

2003 1400hp Cat 3412Es, 1800hrs

I noticed some wear on cover plate of the sherwood raw pumps as well as some on the wear plate. Engines run at normal temperature, only possible symptom has been a little bit of steam when decelerating from 1900rpm cruise.  Just a little, goes away quickly.

hard to describe the amount of wear, but numerous grooves, some as deep as 0.25 MM.

impellers look good, no set, vanes in good shape.  seems like it's time to replace the covers and wear plate? How much wear is acceptable?

[Tommy]

Hi Pascal,

I would consider that as water pump cavitation. Usually it would be fine, but if it becomes worse, then the water pump shall be replaced. I am not sure about the tolerence of the wear rate when a repair/replacement should be done. Can anyone contact the pump supplier and suggest Pascal?

[fanam77]

Hello Pascal

Some steam is typical in a marine exhaust and it does not necessarily mean that there is a problem with the water pump.

Slight wear is normal for that component and is typically not a problem until a decrease in cooling system performance is observed. T

he parts you have described are maintenance items for that pump. Per our maintenance guidelines the pump requires service when the differential pressure exceeds 15 psi.

To ensure the pump is operating properly we would suggest you contact your nearest dealer, who can inspect the pump and provide the best repair option if needed.

Check here for your nearest dealer:  http://marine.cat.com/cda/layout?m=214789&x=7

[Tommy]

Hello, fanam77.

May i check with you why are you mentioning the exhaust gas in the raw water pump? Is the exhuast gas forced to blow into the raw water pump? Would you please explain in more details... Appreciated!

Regards, Tommy

[fanam77]

Hello Tommy

The steam in the exhaust system is mentioned only because the sea water is mixed with the hot exhaust gases after the sea water has run thru the heat exchangers of the engine.

When this mixing of sea water and hot exhaust gases occurs then there is the possibility of steam to be produced in the exhaust which is very normal.

The exhaust gases are never forced or blown back into the sea water pump, all the mixing of the sea water and exhaust gases is done in the exhaust system after the turbo charger on the engine, this helps cool the exhaust gas just before it exits the vessel.