Eric of 1967beetle.com messaged me recently with a diagnostic situation. Eric explained that he was hearing a strange sound in his engine. He even made a short video of his running engine.
I listened, heard “something”, but could not come to a conclusion. Had it been the Generator bearings, I would have suspected a growling. I could not hear that. I suggested that it could be something to do with the Fan—maybe the Fan Nut on upside down?—maybe a cracked Fan? It did not sound like a Fan rubbing the Fan Shroud. Someone else thought that it might be a connecting rod. I asked Eric if, after accelerating, then letting off the gas, he heard a heavy thumping. No. Well…that seemed to limit our attention to the Fan. In the end, Eric’s mechanic was called upon to diagnose and remedy the problem. The Fan had succumbed to metal fatigue and had cracked where the Fan Hub seats on one side and the Wave Washer, on the other.
Eric wanted to install a new Generator which he had on hand—which turned out to be a good thing because the original one was quite troublesome to disengage from the Fan and was rendered useless in the end. With the replacement Fan and the new Generator installed, the Savannah Beige was, once more, purring down the roadways!
In choosing a good German Fan to send to Eric, I looked at several which I had on hand. I found one similarly cracked. Another was severely rusted at the Hub. Rust does a number on metal, weakening it. That one also was discarded.
Yet another problem which can occur to the Fan is “wallowing”. If the Fan Securing Nut is not properly torqued onto the Generator Shaft against the Fan Hub, the Fan will begin to “rebound”, causing the opening for the Hub to become distorted. When this happens, the Fan must be discarded and a fresh one installed. The Hub, also, must be inspected for damage.