TR2/3/3A Water pump issue

[cammau29]

1959 TR3a new water pump shaft snapped which holds pully with Woodruff key. Second pump key shears distroying inside of pully. Has anyone else had problems with Lucus Pump & Pully

 

[sp53]

Something is not correct perhaps a bent pulley something stuck in a pulley like a rock or a really bad alignment of the pulleys

 

[charleyf]

The most common cause of such pump failures is having the belt to tight. You will be surprised just how loose the belt can be and still run the water pump and generator. Watch your amp gauge to see that the generator is charging after loosening the belt. Easy to spot.
Charley

 

[bobhustead]

I had an aftermarket pump in which the keyway was 5mm, while the original is 1/8 inch. Either of the conditions you report could be brought on by this mismatch. A machine shop can easily widen the keyway.

Bob

 

[DavidApp]

The pully needs to be a very good fit on the pump shaft. A tight push fit. Any play between the pully and shaft will allow the pully to wobble a little as it turns. This will put a lot of load on the threaded portion of the shaft. Also there is an extra thick washer under the nut.
I got a 5 vane pump from TRF that has a larger diameter thread than the original pump. I also got a new pully but I did notice that the woodruff key supplied did not match both the pully and shaft. It was to narrow for the pully. I bought a new key that fit the pully and carefully filed the key to fit the shaft key slot taking an equal amount off both sides of the key.

The photo is of the two shaves showing the thread difference.

David

 

[Frank Canale]

Thank you for the pictures and information about the beefier shaft, That is a big difference. Frank

 

[bobhustead]

I believe that the malfitting keyway on my pump was 3mm, not 5mm. David's fix apparently accommodated the same problem.
Bob

 

[DavidApp]

When I rebuilt my engine I put a new pump in it as the old pump bearings were shot but used the original pully. Everything seemed to fit ok.
After a club drive where a fellow member's TR3A water pump failed at the threaded section of the shaft I went back and gave my one a second look. The old pulley had a small amount of play in its fit on the shaft and with the amount the pully overhangs I could see that the pully would wobble a little with every revolution possible causing the thread to fail.
That is why I replaced both the pump and pully. The pully fit was tight. Not a press fit but a tight push fit.

David

 

[Sarastro]

I think you are using the same pump I used: the infamous "improved" one with the five-blade impeller.

I found that the slot in the shaft was sized for a no. 5 SAE key (1/8" thick), but a 3mm key was supplied. I got the right key, but then it didn't fit into the pulley well; I had to grind the edges of the key. I also found that the pump body interfered with the pulley and had to be ground down a little in a couple places. Finally, the nyloc nut and washer were not sized right; the nut would not thread onto the shaft enough to engage the locking part. All these problems can be fixed, as long as you know about them. But it's still annoying.

Yes, the pulley absolutely must fit tightly, with no wobble or slack.