MikeC

Thanks to everyone for replies - I suspect it may well have had the "wrong" pump fitted at some point prior to my ownership. I'll just press on with a larger belt I think.

Thank you Richard and Colin for your prompt replies. Richard - the surprise is that if I have been supplied with the correct pump AND fan belt for the engine, then the belt should fit? Supplier was James Paddock, whom I have always found to be very good and helpful - I have noises with them at all. Rimmers also list the same part number for GK engines. They also list two pumps but list the same part number for the belt for late GK engines and the earlier (GE) ones! I think in theory the later engines have a different pump pulley size but also a different crankshaft pulley? So the same belt should work in each case? I think the later GK engine water pump is the same as the one fitted to MkIV and 1500 Spitfires? The listed part numbers seem to suggest that to be the case. The puzzle is that the old pulley I've removed is smaller than the new one whilst the old fan belt is longer than the old one. I can make the old fan belt fit with the new pump but I can't fit the new fan belt. Colin - the old belt doesn't have any useful marks to indicate the length. But the new one is GCB 11025 which, as I understand it, should be correct and matches what you've said. The engine block is clearly stamped as a GK version and the registration date is 1971 so I would have expected the late engine pump and fan belt 11025 would fit. I guess I really only need to get a new fan belt that is the same length as the old one (or trust the old one for a bit longer but I didn't really want to do that). However I am just trying to figure out what it is about my car that is non-standard. If I could somehow learn the original pulley diameters for the crank and the water pump I may be a step nearer. Thanks again for your replies.

Hello all. I recently had a noisy water pump. The noise got worse. So I lifted the bonnet whilst the engine was running only to be sprayed from head to foot with rusty water. Water escaping from the water pump, sprayed into a nice disc by the fan. Lovely. Wasn't really dressed for that. Anyway, cutting to the chase: I ordered a replacement pump, carefully making sure to order the one for the late 13/60 GK engine. Also ordered a fan belt of course. Today I fitted the pump but the new fan belt won't fit. Even with the dynamo fully loosened and at its slackest position. On closer inspection I found that the pulley diameter is bigger than the one I removed. I called the supplier and they reassured me that the GK engine definitely has the bigger diameter pulley but also a different crankshaft pulley, so the same fan belt should fit. It doesn't. The fan belt I've removed is slightly longer. I can get the old one back on but the new one just won't go. Most of what I see under the bonnet is original or else I have fitted it. I have had the car 18 years and am the second owner. I suppose the water pump could have previously been replaced with the incorrect one, but that doesn't explain why the correct fan belt won't fit. Does anybody know what the correct diameters are for the crankshaft pulley and the water pump pulley? For a 1971 GK-engined 13/60? Or else what size fan belt I need to order to make it right? Thanks.