Water Pump Rebuild

[peterhulley]

Just rebuilt my JUPITER water pump using a new water pump casting supplied by JCC (part No J54505). When the water pump was refitted above the front timing case cover, the distance between fixing points on each component, for the "dynamo and water pump strap", was 20mm longer than the distance between the holes in the strap, when the pump casting inlet and timing case outlet were metal to metal. On checking the old water pump casting I took off, the water entry diameter was longer on the new one than the old one by about 20mm, and this was making the distance between the strap fixing points too far apart. I am tempted to remove 20mm from the new casting - but that's a bit final. Why I am hesitant is that I do not know if the part I took off was standard or had been previously modified to suit and because the engine was rebuilt whether the front timing case cover is original JUPITER or from a JAVELIN
Any help would be appreciated, either on the dilemna above, or the questions below.
Can anyone advise on the folowing:
1. The difference between the JUPITER water pump housing assembly casting (part no 52972) and the JAVELIN water pump housing assembly casting (part no J54505)
2. The difference between the JUPITER front timing case cover (part no J54531) and the JAVELIN front timing case cover (part no 54662)
3. Is there any dimension that can be checked on either the water pump housing and/or the front timing case cover to confirm either component is suitable for a JUPITER or a JAVELIN.
4. Has anyone had any experience of rebuilding a water pump for a JUPITER using a new water pump casting they can share.
Regards,
Peter Hulley

[Drummond Black]

Peter,
I have build six Jupiter pumps using ALL new parts and, in nearly all cases the same question arises. Without seeing your parts I recon the strap you took off was correct and this sets the distance between front timing case and water pump. The original Jupiter front timing cases were definately shorter, however over the years Javelin FTC's have been fitted. A lot of Jupiter Water Pump's I get in have the input tube shortened to an extent that it is difficult to get the hose to locate and seal effectively.

I normally suggest that you carefully measure the distances, planning to allow a 3mm gap between them on final assenbly, and cut both the FTC and the pump. This allows plenty length to locate the joining hose. I hope the above makes sense. Send me an e-mail if you still require any further info. I think I usually incorporate eight mods into every pump now.

Please advise on your outcome.

Drummond

[Forumadmin]

I concur with Drummond, and add that on the Javelin I have made a boss to fit on both the timing cover and water pump and these are mated together with an O ring and bolted up with Allen screws. This makes a solid foundation that is not pulled over by the fan belt. On the Jupiter I have added a stay between the distributor locking plate and the two left water pump casing bolts. This adds to the strap that also supports the dynamo on the left side. This helps eliminate the fan belt from pulling the water pump out of the short rubber tube.

By the way Drummond took my water pump off the Jup today to find part of the brass impellor ring has disappeared. So I guess we were lucky to complete the last 400 miles on the European trip. There will now be a search to find where it has gone! Whether this fracture was the cause of the leaking or it fractured because of another problem such as lack of grease and overheating I doubt if I will never know. The motto now is grease and oil every day when doing 400 miles a day for 10 days! From memory of the trip the noise in the pump did not start until the last 100 miles, so it was probably an effect, not the cause.

[peterhulley]

Thanks to both of you, I'm now feeling a more comfortable about removing material.
I will do some more dimensional checks and the square off the outlet from the timing case cover and reduce the inlet to the pump housing to give the 3mm gap and a good area for the clips to clamp on.
I have incorporated an internal thin walled brass tube inside the mating diameters (suitably cut away so the out flow is not restricted) and the additional tip re strapping to the distributer mount should ensure its fixed in all planes.
Thanks one again.

[Forumadmin]

Peter,
Be wary of a brass collet inside the aluminium as you will get parasitic corrosion. Better to make out of ally. You can see this corrosion occurring where the heater pipe tap exits. Often this thread corrodes so much the tap becomes loose.