A week ago I asked for advice, suggestions and opinions and the response
from the List has been fantastic. My thanks to all who have contributed to
this thread.
The 4 blade fan needed to be replaced. The blades were bent and deformed
and no two had the same pitch angle, one was even reverse pitch. The purist
in me wanted to rebuild the original, but the practical and economic aspects
prevailed.
To summarize the various comments, suggestions and advice that have been
submitted thus far:
1. Keep a 4 blade fan and replace the water pump with a 6 blade impeller
from BFE.
2. Replace with a 6 6 blade Tropical Fan. Hard to find I am told.
3. Replace with a Volvo 122 S 6 blade. File out 2 of the 4 mounting
holes and it will fit.
Mount yellow 8 blade fan by doing the following:
4. Move the radiator forward. Can't do this on a TR4. The bottom of
the radiator hits the cross brace on the front of the frame and I am
unwilling to remove the brace. One owner of a TR4A moved the mounts on the
radiator back 5/8 inch and achieved 3/4 inch clearance between the 8 blade
plastic fan and the radiator.
5. Change fan hub extension. The original hub is #128318. One TR4A has
a shorter extension #142121 in place with the 8 blade plastic fan.
6. Change fan hub extension to the one from a TR3. This may be the same
part number referred to in the above paragraph. One list member is trying
this solution and I hope he posts his results. I am concerned that there
will be interference with the steering rack and the cross tube. You will
also need to get another crank bolt which is shorter.
7. Reverse yellow fan. Remove hub extension and check diameter. I used
a compass to scribe a circle on the end surface of the hub, and found that
the shape was more oval than round. The high spot was more than several
thousandths out and I carefully removed the material with a fine wheel on the
bench grinder. The yellow fan then fit when reversed.
8. Electric fan mounted in front of the radiator as a pusher.
The solution I chose was number 7, to mount the yellow plastic fan
reversed. I already had the fan and associated hardware. After slight and
careful grinding to the hub, the fan fit reversed. There is plenty of
clearance from the radiator.
With the fan reversed the blade ends are running backwards. What was the
trailing edge is now the leading edge, and the airfoil shape of the blade is
no longer as effective as designed. Thus the efficiency will suffer, but I
am told will be more than adequate for the job.
If I had not already had the yellow plastic fan, I would have chosen the
electric fan. As it was, I had a workable solution at no additional cost.
Thanks,
Bill Grubb
62 TR4
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