Monthly Archives: June 2019

Splish splash, seized water pump.

Just as I was getting near to solving the engine balance issue I discovered my water pump was seized. The pump had been modified in the UK and although they were on the right track the mod had a fatal flaw. An original factory pump uses a series of cork seals but my pump had a modern ceramic seal fitted to the impeller (see pic) with a steel insert fitted into the body to act on the seal. However, they had not taken into account the reverse thrust pushing the impeller back onto the rear PB bush, gradually the impeller was worn down, this allowed water to travel to the front and into the main bearing. I had fitted a sealed bearing there years back but it still seized.

Original pump with seized bearing

Impeller, note worn section and modern seal

Next I order a new one from Cavalitto (€400 plus shipping)

New water pump

When it gets here a trial fit reveals a problem, it’s too long by 5mm, which means the fan belt does not align with the crankshaft pulley. I’m starting to have visions of the radiator horrors from the past (www.narrywoolan.com.au/lancia-aprilia-1070/radiator)

I contact Enrico, he promises to look into the problem. A few weeks later he ships another that they have modified. It “almost” fits, but still needs another 2mm trimmed to get the the alignment correct.

To cut a long story short I machine the body and the various internal parts to get the desired alignment.

Trim 1mm off the flange

Mill 1mm of the other body half

2mm off end of impeller and matching amount on body

Cavalitto have sold a lot of these pumps so in trying to see why it didn’t fit on my engine/radiator there could be difference in the extension on the front engine mount, I have one spare that is longer, maybe 2nd series are different, I really don’t know the answer.

A look inside the Cavalitto pump shows they have thought the design out thoroughly. The impeller has a collar on the back that works against the rear bush, there is a modern seal that runs in a nylon bush and a sealed bearing. The engine is about to go back into the car so we’ll see how this pump works…

ngm