Water pump and fan blade

I think I might be becoming a pest here, but hey ho that is what forums are for !
so here I go again

I have removed the water pump on my 1948 MK4 and see that there is some damage to the casting that the fan bolts to, and the threaded brass fitting for the grease nipple -see pictures, I am not too concerned as I think the casting could be chemical metal repaired, however do you think this would be ok to run as is if I cannot repair it and does anybody have a spare ?

As I have the water pump off and can get access to the chain drive, is it worth replacing the chain as a matter of course or do these last a very long time, I think this engine has done 75K

The broken casting might affect the balance of the fan. If it’s free enough to rotate you could check this and possibly mount the two balance sectors on the same side to compensate.

The chain is a double row one and I don’t think you need to change it. It’s not so easy to do whilst the engine is in the chassis. Leave well alone would be my advice.


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I agree 100%. I do have some spares, but i am a bit far away and IiRC at least one of my spares has a similar problem. You could cosmetically fix it but more important would be to balance it.


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Hi Mike,

Since you are in the UK it’s just one month to Stoneleigh. :+1:

I won’t be able to make it this time, but possibly in next year in March.


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Hi Mike,

Water pump broken element is not too concerning in my opinion. Why was it broken, was it dropped? An assessment of pump function, worn out issues, and so on is worth the time while it is out. I would be sure to evaluate bearing and seal function due both to age and that the balancing pieces
C.1753 Piece, Balance, for Fan L.34 As req’d (page 20 Spare Parts Manual)
look like they have been put in place without regard to balancing previously (perhaps when pump was out and dropped). Note there is no limitation on number of balancing pieces to be used. If pump function is satisfactory, balancing pieces may be sufficient to overcome missing chipped mass. Also comforting is that the missing chipped mass is close to rotational center and thus has reducing moment of inertia consequences for imbalance considerations in comparison to a possible fan blade imbalance much further out from the center of rotation.

In my my personal experience examining only a handful of chains, those chains have looked good up to 120,000 miles. The problem with considering a quick chain exchange is that the timing cover cannot come free enough for chain access without removing
C.2808 Centre for Damper J.7 page 16.
For me, when C.2808 is to be removed, I’ve decided to go after full engine rebuild.

Not knowing the scope of your desires, intended future use, and wear history of the engine, I would be inclined to caution about aiming for chain exchange without indication of need. On the other hand, if doing a full rebuild is where the joy would be for you, these engines can be fun for the tinkerer with top quality machine shop support.

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I agree with Roger. That tiny amount of mass missing so close to the centre would not have any detectable effect on the balance at the usual range of engine speeds. Helping this is the fact it is alloy.

Definitely dismantle and inspect the water pump while you have the opportunity. Parts were available from Alan Gibbons at alan@ssjaguar.co.uk. He also has details on dimensions and clearances for the different models of water pump used over the years. If you try to do a static balance, all friction must be prevented - no seals, no oil or grease, no contact of any sort except the balls in the dry bearings.

The misaligned grease fitting looks like it might have been just poorly fitted and is cross-threaded. If you are lucky the thread in the casting may be good enough to accept it back in its correct alignment, but if the thread is damaged be careful to avoid overtightening.

I have a few spares of the balance weights for when I overhaul mine, and noticed a tiny hole in each, at different positions. I think that when the assembly was balanced in the factory, the weights often overlapped and were drilled and pinned to the hub. This would help to reset the correct balance after an overhaul as long as you recorded the original assembly orientation.

I agree about the timing chain, they are normally only replaced at major overhaul time and even then they are only replaced as a matter of course, and not because they are worn out. The only fault I’ve experienced with a timing chain in more than 50 years of fiddling with engines is one roller (which are hardened steel) split into two halves. The chain still worked perfectly because of all the other links in contact with the sprockets. The two pieces just stayed in the bottom of the timing case - after leaving a few small scars around the cover.

Peter L

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Thanks all for the detailed responses, I have not taken the water pump to bits yet, but will be giving it a complete overhaul when I do with all the advice I have received, I believe the pump got damaged when we transported the car to my work shop ( That’s what I call my two 8X20’ steel containers !) ok to work on a Austin seven, my last car, but a tight squeeze with the Jag, and when I have completed one side of the car I have to take it out of the container to realign it so I have room to work on the other side, I am on the passenger side now, where most of the engine parts are accessible so that’s why you lovely people are getting bombarded with engine question now !)
I use to live in the US on a ranch with 8 acres and a three car garage wish I had that now, however you have to work with what you have got !

The damage occurred I believe because there was a rag under the bonnet on top of the radiator to stop any rubbing whilst in transport, unfortunately, the car was in gear when we were unloading it and the engine turned whereby the rag got caught in the water pump belt drive and went around the top pulley

Thanks all

That is correct, the fan and 2 weights were a matched set.

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