FYI for any of the SD25 folks. I ordered a spare water pump today for mine. It was changed approx 2.5 yrs ago now and by the time that one fails they (water pumps) may have gone the way of the Beta machine.
(I'm anal I guess) I ordered from Nissan and the part number is, (according to the invoice that I got yesterday) 21010-10G26 and cost $77.49 Ca $$'s . Parts man at Nissan says 3-4 weeks as it comes from Japan. Comes with gasket and studs for clutch fan. I thought that was a pretty good price actually for OE Nissan stuff. FWIW (no I did not forget the 1 in front of the $77.49) Parts man was just as surprised as I was when that price came up. I would not have ordered it had it been over $100.00. (not only anal but cheap too) I assumed that if it comes from Japan and Nissan it will be a new pump.
Paul
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
I got the pump from Napa with perfect help from asavage - Thanks a million.
I checked that the pump looked the same as it did and it did apart from one little detail....
I started to tighten the 3 bolts and when i tried to tighten the last bit on the lowest bolt it suddenly snapped !!!!
I loosened the other 2 bolts and at a very close inspection i saw that the housing of the new pump was about 2 mm thinner over the mountings hole so that the original 2 bolts with 12 mm head was just 1 mm to long.
I tried everything i could to get the broken bolt out, but it was totally stuck so the only option i had left was to drill a new hole over the old one, and carve new threads.
Drilling that on free hand, and carving the new threads in the engine block on free hand while it was still mounted in the car, was a bit nerve-wracking. I know that best thing would be to take out the engine but that option is not available for me since i don't have a garage of my own.
But it went fine and i got 2 shorter bolts and could tighten the pump to the block without any more problem.
I have driven the car a couple of times now and it seams to hold perfectly the area around the pump is totally dry. The new pump is more efficient and i can feel that there is less vibration in the car now.
I ordered from Nissan and the part number is, (according to the invoice that I got yesterday) 21010-10G26 and cost $77.49 Ca $$'s . Parts man at Nissan says 3-4 weeks as it comes from Japan. Comes with gasket and studs for clutch fan. I thought that was a pretty good price actually for OE Nissan stuff. FWIW 
(no I did not forget the 1 in front of the $77.49) Parts man was just as surprised as I was when that price came up. I would not have ordered it had it been over $100.00. (not only anal but cheap too) I assumed that if it comes from Japan and Nissan it will be a new pump. 