6-71N Raw Water Pump

[Freestyle]

Got a little scare when I lost raw water cooling on the starboard engine while docking. After tying up I went down to figure the cause. The pulley on the raw water pump shaft had flown off the shaft and rolled all the way to the aft end of the engine room.

Now I am trying to figure out why this happened.

Should I be able to turn the shaft on the raw water pump by hand now that it is not hooked to the engine?

I am thinking the bearings in the pump went bad, seized and that is how the pulley broke free.

Any other ideas appreciated.

Bruce
Freestyle
1976 43 DCMY

 

[REBrueckner]

I may be crazy, but I thought 71 series raw water pumps were gear driven; My 8v71's sure enough are....but I think on my old 6V53's, the coolant pump may have been belt driven...

anyway, you'll not be able to turn a raw water pump via the shaft by hand as the impellers offer to much resistance...

 

[yachtsmanbill]

The front of this guy has a clutch driven bilge pump plus the AF circ pump, with the sea water pump gear driven on the back. 1940 ish 6-71N ws

 

[newinlet]

My 671n- 78 vintage has a gear driven raw water pump

 

[spartonboat1]

I may be crazy, but I thought 71 series raw water pumps were gear driven; My 8v71's sure enough are....but I think on my old 6V53's, the coolant pump may have been belt driven...

anyway, you'll not be able to turn a raw water pump via the shaft by hand as the impellers offer to much resistance...

My '72 vintage 6-71's are dual belt driven raw water pumps on the front of the engines. The internal pump is gear driven. P.s., I lost my alternator pully 2 seasons ago and it fiended the shaft in the process. May well be that in the situation above, the holddown screw loosened and the pulley backed her way off the shaft! I try to put a wrench on all that stuff every season, but don't always get there.

 

[REBrueckner]

Ok, so Sparton confirms some raw water pumps are belt driven....

why the water pump drive belt drive mechanism fails: broken/stressed pulley, worn/loose drive belt(s), worn/bent shaft, worn/wobbly bearings, loose set screw/lock key etc or associated component failure like an alternator....or even the drive (engine shaft) pulley may be loose/worn/broken...

 

[LENZ]

Got a little scare when I lost raw water cooling on the starboard engine while docking. After tying up I went down to figure the cause. The pulley on the raw water pump shaft had flown off the shaft and rolled all the way to the aft end of the engine room.

Now I am trying to figure out why this happened.

Should I be able to turn the shaft on the raw water pump by hand now that it is not hooked to the engine?

I am thinking the bearings in the pump went bad, seized and that is how the pulley broke free.

Any other ideas appreciated.

Bruce
Freestyle
1976 43 DCMY

Bruce, My pump on my 1972 43 DC, 8V53N DD is also belt driven and went bad recently, I bought a rebuid kit from "Diesel Specialist" in Baton Rouge LA. Cost was $108.00 and included, Shaft, bearings, mechanical seal and impeller. I thought that was a good price. Their Ph# 1-800-768-0742. They do have a exchange program and I believe the cost for a complete rebuilt pump was around $200.00 or so.

Thanks Lenz