13/60 water pump pulley diameter

[MikeC]

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.

 

[Colin Lindsay]

I thought the water pump pulleys were all the same size, part number 201329, but with the latest Heralds - especially a 1970/71 car - it wouldn't surprise me if Triumph used a different pulley from another model.

A fan belt should be easy to source - get a piece of string, put it around the components following the same route as the fan belt, and measure the length required. Any good autofactors will sell you a belt of the required length. Alternatively, if the old belt will fit, read along the outer edge and see if there's any measurement or part number printed along the edge, as in my GT6 belt in the photo. This will help source a new one.

The one I've found listed for later Heralds is Unipart GCB 11025

Earlier Heralds, 1200 and 948, are listed as Unipart GCB 11038. 

If your original belt is a good fit, I'd try to source a replacement locally like-for-like.

 

 

[Guest]

1 hour ago, Mike Cook said:

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.

Hello Mike,

If the pulley dimeter [supplied] is bigger than the one you removed, it's hardly surprising the fan belt will not fit - as such it is fair to assume that your car had the incorrect pulley size but had the correct fan belt to fit the set-up. Am I missing something here ??

Who did you source your replacement pump from ??

Regards.

Richard.

[MikeC]

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.

[Guest]

Hello Mike,

The other option is to have your original pump reconditioned by this company and send back the JP unit.

Not only are they brilliant in all aspects but also give a life time guarantee on all their units. I know Colin has used them, as have I on a number of occasions.

Herald reconditioned pump about £50 including that guarantee but excludes carriage - still cheap as chips for the service and lifetime product. Worth thinking about.

Regards.

Richard.

http://www.ep-services.co.uk/our_company

[KevinR]

My understanding is the diameter of the pulley depends on whether the car is fitted with a Generator or an Alternator.

To get the alternator or generator running at the optimum speed, the pulleys are different diameters, so the water pump pulley was changed to accommodate the same length of fan belt.

Given the age of the cars, it could easily have had the wrong size pulley pump fitted at an earlier time in its life. 

[DanMi]

when I replaced the water pump on my old 1500 engine the replacement (repro) pump did have a bigger diameter pulley than the original just measure the fan belt that fits and source one the same length. Modern repro parts are not always exactly the same as original

 

[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.

 

[PeteH]

By my reckoning a larger dia on the water pump effectively reduces the rotational speed of the Water pump and the Fan?. Was this the intention of the later change?. Reducing the Crank pulley dia, would further reduce the rotational speeds too?.

This might suggest that, the original intention was to reduce the rotational speed of an Alternator? as opposed to a Dynamo? . (having to) Using the same belt length could be due to possible obstruction by some other engine or body part?.