Water pump impeller size

Dollywobbler · Post by **Dollywobbler** » Mon Sep 26, 2011 10:22 pm

Sorry to bang on about this (see cambelt change in FAQ section) but much as I trust Mr Fenwick, I wouldn't mind more opinions - especially as I'm not going to be able to get anywhere near the car again until at least Wednesday.

The new water pump for the Mk1 has an impeller that is 1cm smaller in diameter than the gunked up mess I removed earlier. Otherwise, it looks exactly the same. I don't have much of a grasp of water mechanics, so it could be that this is perfectly acceptable if not better in action than the larger one I took off, but I'd like to see if anyone else has encountered this! I really don't want to go through all this pain only to have generated another fault.

Kitch · Post by **Kitch** » Mon Sep 26, 2011 10:44 pm

You might find that originally two different engines had two different pump designs (because one had a more restricted orifice for the pump to mount in) and since then one of the manufacturers has realised one pump will suffice for the two different engines.
It\'s very common to see totally different inpeller designs. If you\'re unsure let me know what part number you\'ve got and I\'ll check it out for you - I used to be a parts man in a previous less happy life!

FWIW - there is a cambelt part number change on the XU somewhere along the 80\'s. I think it was the tensioner design that changed, but it could have been the waterpump pulley.