The Stovebolt Site Forums The Shop Area Engine Shop Water pump - short shaft or relocation plate?

Yes, you can have overheating issues with the pump/fan down low. Especially if you're driving slowly or in city traffic.

Shortening the shaft can be somewhat easier or a lot of work. To find out, you need to use a press to lift the hub up and look at the shaft. There were some pumps which used a stepped shaft...meaning you just pressed the hub on as far as it would go and it was automatically at the right spot when it bottomed against the step. Then there were some which had a straight shaft and you pressed those on using a spacer...you stopped pressing the hub when the hub just contacted the spacer. In my experience the stepped shaft are more common (because they were cheaper and faster to assemble) and you'll have to turn the shaft down to relocate the hub. If you have a lathe and if you can disassemble the pump, not a really bad job but otherwise no...not a good project at all and if you're not good with a metal lathe you can ruin it. The hub has to fit tightly. Friction is all that holds it to the shaft and you don't want it coming off.

Personally I got a short shaft pump and did away with the fan entirely in favor of a thermostatically adjustable Spal puller fan, a shroud and an alternator. After hearing a friend who ran a machine shop talk about spinning 5 random 235 fans I don't want one anywhere near my engine. They're too old and too many things could have happened to them. Only one was balanced fairly well, he said. According to him it wasn't just the weight part of balancing either. If one or more blades had been bent or damaged in some way even slightly or if it had cracked down near the center it would cause trouble. Back when a made in the USA pump cost $20 or so that wasn't so bad. Today you get some iffy made in who knows where water pumps and a short shaft type might cost over $200. I don't want a fan shaking it apart. Besides without that fan the engine will run more quietly. As for the short shaft pulley, I'm not certain where those can be had. Good luck!