1971 Se1 4.2 SWB Man-OD Water Pump, seemingly pointless hole in cy' head- see most recent post.

[johnlakey182]

Waterpump 1971 Jaguar XJ6 Se1 4.2 ManOD

A while back I started the XJ and could smell coolant, so stopped, had a good luck and realised it was leaking from the water pump.
A little prodding confirmed the pump shaft had plenty of movement in it, so I tried to order a new water pump. The usual suppliers (SNGB’, David Manners etc) all told me its not available for my car and that it would need rebuilding. They quoted 4 -6 months to do this and also said if it’s already been done its probably too thin to machine and rebuild again. Saying this is a unique water pump that was not fitted to any XK engined car other than Se1 4.2, which I was surprised about.

A bit of googling conformed it is a different part number than the norm but I found someone selling that part number in Australia and so took the plunge as I didn’t want to leave the car in bits for 5 or 6 months while I waited, only to be told my pump can’t be rebuilt…
I’m hoping to fit it next week and opened the new pump today but it has a different pully on it – see pictures. Although the pump body looks the same.

I’ve carefully put the impeller in a vice today and managed to loosen the pully with the big nut on and could see the centre shaft withdrawing from the impeller. See pics.

The double belt pully I have on the new pump protrudes too far to refit the visco fan so the only thing I can think of doing is fitting my old shaft to the new pump but if the play is in that I don’t feel that’s wise!

Also if I do decide to tackle it next week is it worth taking the bonnet off totally to make it easier to get to or is that a nightmare waiting to happen? It looks like its only 4 bolts to remove the whole bonnet.

I have attached pictures as well of the old pump in situ and the new pump I have with the different pulley.

I’d be grateful for any knowledge or info please as I’m not sure where to go next!

Thanks

John

[johnlakey182]

part 2 pics

[piman]

John,

why do they machine it for play in the shaft? The usual failure in water pumps is the bearing, and once worn there is too much play for the seal to work. If you are able to remove the shaft from your original pump why not just replace the bearing and seal?

Alec

[poprivet]

The problem with parts sellers is they, well, only sell parts. They would contract any 'work' out to a third party.

I would think a decent engineering workshop could rebuild the unit easily and without paying the middleman

[mike020150]

Checking the original parts manual, four versions of the water pump are listed for the 4.2 litre engine, all complete with pulleys. Nevertheless, all of them use identical body, impeller and shaft part numbers. That implies it's only the pulleys (3 versions) and other bolt on items which differ. It may well be that when you remove the old pump, you will find that the new one does have just enough clearance, albeit you will have an unused pulley rib, probably for running an aircon compressor or similar. Mike.

[johnlakey182]

Thanks for all the replies, much appreciated.

They have confirmed where my brain is - take the old one off and see what I have when both are sat on the bench as the casting of the new one looks the same so I may be able to fit my pully, presuming that is not the part causing the leak...

How easy is removing the bonnet on a Se1 XJ? It would stop me from banging my head on the edges (which I know myself well enough to know I will do!) but am I opening a can of worms doing that or is it as simple as it looks? Four bolts on enormous brackets.

Thanks

John

[mike020150]

Stating the obvious, the bonnet is quite heavy and awkward to manoeuvre. It is also very adjustable, having sliding captive plates inside the hinge fixing points. It's best to mark clearly the starting position before loosening any of the hinge fixings or it will take some time to return it to a position where it shuts properly and doesn't catch anywhere. Dependent upon the assistance you have available, it may be easier to try supporting the bonnet in a more open position than removing it completely. Mike.

[PaulGover]

... How easy is removing the bonnet on a Se1 XJ? It would stop me from banging my head on the edges (which I know myself well enough to know I will do!) but am I opening a can of worms doing that or is it as simple as it looks? Four bolts on enormous brackets. ...

As Mike suggests, removing it is relatively easy. Getting it back in the right place with even gaps is the hard part. And, as far as I recall, it's heavy. I must have taken one off years ago, because I changed the engine, but I'll be d*mn*d if I can remember what was involved.

As long as it's opening properly, I don't think you are likely to hit your head - when working on it, it's a looming presence! Possibly remove the safety catch on the LH side, as that sticks out a lot, and maybe split some hose and tape it over the edges if you're worried about them in particular.

Probably better, you can disconnect the bonnet stay (on one of the hinges) to let bonnet open until it rests almost vertically on the front bumper, which gives lots of clearance for anything short of an engine-ectomy. <Note added> Check before raising the bonnet that far that it won't hit your garage roof or supports (he says from experience....).

[johnlakey182]

Finally fitting the rebuilt water pump and when I came to clean up the surfaces yesterday I noticed a hole at the top - see picture- which appeared to have the remains of a rubber bung in it.

A bit of poking showed it was full of what appeared to be lithium grease (very pale grey in colour). The rubber bung/O ring was very broken but definitely there. I very gingerly poked a small screwdriver in and got about 2.25 inches in before hitting metal. I've cleaned up the hole and it appears to have a ridge on which a bung or O ring could sit.

The gasket and pump are solid over this hole, effectively stopping it from doing anything as far as I can tell, so it may be a hangover from an earlier design?
Or some kind of vent hole for the cam chains I'm missing the point of? But why fill it with lithium grease if that is the case?

See pics.

A careful study of the SNG B XJ PDF shows they don't offer said bung or O ring and, in fact, the hole is not in their drawing...

So I thought before I go ahead and fit the pump, covering up said hole I thought I'd better sense check it.
I have no desire to take it to bits again in a week or so because I've missed out an essential part. Even if I can't see the point of it...

Happy to be told I'm being an idiot - better that than waste more time and money on it.

Thanks

John

[mike020150]

Unfortunately, I can't give you a definitive answer to your query. Like most of us, rebuilding the front of an XK engine is something only tackled infrequently so much of the detail is lost as the years pass! However, checking an original XJ parts book, the mystery hole is shown in the line drawings so it should definitely be there. Similarly, no bung to cover it is listed. From its location, I would guess the hole aligns with the shaft supporting the timing chain intermediate gear. So, maybe whoever designed the timing cover believed access to the nose of the shaft would be required in service. I can't understand why but the timing gear/tensioning arrangements of the initial XK engines were slightly different from those of the Series XJs. As long as you fit the water pump gasket correctly, there's no chance of oil and water mixing in the engine so I'd carry on with the rebuild without worrying about it. Mike.

[johnlakey182]

Thanks Mike, much appreciated.

There was definitely the remains of a rubber bung in the hole but, like you, I can't find any mention in the manuals etc so I guess whoever has been there before (and although it is a Se1 it has never been restored as such just maintained and has done about 60k from new) must have thought putting a rubber plug in there was a good idea but of course with the heat and pressure its just broken up and I suspect been turned to dust by the timing chains.

An odd thing to do if it's not there in the parts book though!

[andypryce]

Could it possibly just be there to hold the engine during production, eg on an assembly line?

[johnlakey182]

I can see the logic of that Andy, or for casting in some way...

[PaulGover]

...
I would guess the hole aligns with the shaft supporting the timing chain intermediate gear.
...

Could it be a manufacturing requirement for inserting said shaft?

[mike020150]

Unfortunately not, Paul. The timing gear can only be fitted without the timing cover being in position. Mike.