TR-3A Water Pump

[angelfj]

Need help. We ordered (and received) an upgraded water pump from a supplier in England. This pump has a different impeller (5-vane). It is claimed to deliver better flow and enhanced cooling. (we will see???) I did this because I wanted to use an original radiator with the hand-crank hole. Having the hole reduces cooling because some of the tubes are closed off. The theory was for the enhanced water pump to make up the difference. Here's the problem. The pump arrived without a pulley. The instructions say that the original pulley may be used. The original pulley was an interference fit onto the original water pump shaft. The new shaft is undersized to the point that the pulley easily slides over the shaft. Does anyone have a suggestion?

[stuart]

Talk to the supplier first to establish the problem. Some water pumps have pressed on pulleys and some have bolt on. Only the bolt on type are reuseable. Failing that get it sleeved.

Stuart.

[TR 2100]

The pulley is held on the water pump shaft by a nyloc nut, but it's the woodruff key

that stops the pulley rotating on the shaft.

 

I wouldn't quite classify the original pulleys as an interference fit, a close fit, yes,

expecially when you are trying to remove it after many years and the woodruff

key is still in place.

 

Maybe reproductions are made to greater clearances - I'm not an engineer but a

slightly greater tolerance shouldn't affect the functionality of the woodriuff key,

obviously too great a clearance would.

 

Opinion seems to be divided on the benefits of the uprated water pump.

 

AlanR

[Tr4Tony]

My experience of the 5 blades pumps isnt good - whats 5 blades going to do ? shift more water ? faster ........ the issues of cavitation spring to mind, water flowing too fast to cool .......... and so I have proved in my own cars .......... which is why i stick with the 4 blade standard type, just with a slightly bigger bearing in them.

 

I run one in my rally car and its more powerful than most - absolutely no problems. Id recommend the simple and reliable approach here.

 

Regards

 

Tony

[Richardtr3a]

These new pumps without a pulley are a pain. I fitted my old pulley to a new pump and it came loose and damaged the shaft and the pulley. They need to a really tight fit and bolted up hard. Triumph always used to sell the pump and pulley as a unit with a long bolt already placed through the pump flange.

 

I have fitted an uprated pump from Racetorations with their pulley and it has knocked out the continuous leaking gland problems which I suffered for years. I rebuilt a number of old pumps and finally went the new route. There has been no further leaks for at least ten years.

 

Good luck

[Don Elliott]

I bought a new water pump from Cox & Buckles 20 years ago when they were still in Richmond-on-Thames. The seal had been leaking and the mild steel shaft had become rusted at the seal resulting in a reduced OD. This new pump had a sealed bearing and no grease fitting. Since I'm into originality, my neighbour who has a lathe offered to turn a stainless steel shaft for me and also drill and tap a hole for the grease fitting. Since then, it has not leaked coolant in 98,000 miles of driving my TR3A..

 

Also for what it's worth, the newer repro pump had a cast iron impeller which was smaller in OD than the original bronze or brass one. I felt that with more peripheral clearance between the OD of the CI vane and the inside of the pump body, the water flow would be reduced.

 

So we pressed the original bronze one onto the new stainless shaft. Maybe the high flow 5-vane impeller technology was developed to overcome problems with the newer CI impellers. Mine has worked fine after 18 years of driving.

 

Frank - As Alan above suggests, you could add a collar to the shaft or bush the ID of the pulley or you could have a new shaft made with the correct diameter for the pulley.

 

I go by the old engineering quotation, "If it ain't broke, don't fix it".