Water pump/fan taper

gridleak

gridleak

Senior Member
It seems that the reason my fan keeps getting loose on the pump shaft is that the taper is wrong. Kept tightening it but now it doesn't track well.
Searches indicate: 1. The some pump shafts were sold with the wrong taper. 2. Some 2 bladed fans had wrong taper (one guy was destroying these so they could not be used).
The fan on my 29 coupe is a new 4 blade fan.
I want to set this right and don't know if I should get a new fan or new pump shaft, how can I determine which has the proper taper?
 
There is also the chance the woodruff key is the problem. Test fit the ban to the shaft without the key in place. It it goes on and fits snug then you either need to deepen the groove in the fan hub or find a smaller woodruff key. We did an extensive evaluation of fans and shafts several years ago and discovered this problem would show up from time to time.
 
there might be some complicated math formula to test the tapers, but the simplest way I can imagine is to find an original fan and use it to verify the taper.. You are right, it could be either or both tapers.
 
Clinton

How do I know which is the correct taper with the Persian/Prussian blue?
 

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You really don't care which is the correct taper, you just want them to match. The taper on the shaft is a lot easier to modify. Spin the shaft in a lathe or drill press and use sandpaper wrapped around a file to sand off the areas where the prussian blue was rubbed off the shaft.
 
I considered lapping or fitting to make a better fit but part of the problem is that even now the castle nut goes on so far that that I have to add a washer so that the slots in the nut line up with the hole in the shaft.
 
gridleak said:
I considered lapping or fitting to make a better fit but part of the problem is that even now the castle nut goes on so far that that I have to add a washer so that the slots in the nut line up with the hole in the shaft.
Click to expand...

If you are using an aluminum fan then the flat washer is a good idea anyway. On a steel fan it still won't hurt to use it if it helps the castle nut to line up.:)
 
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