Hello, everyone! I am working on replacing the water pump on my V12 XJS. So far, I have pulled the radiator and it is currently in the shop being re-cored. I have removed all the fan belts, and I am down to removing the old pump. Greg has been kind enough to caution me about the Pozi screw shown as #10 in the diagram. When removing the idler pulley mount, there are two studs that should be removed. I gave some reasonable effort to do so, but I was concerned I would snap it off. So, I have left the two studs marked #15, and also stud marked #14. I have looked VERY carefully, and it appears that I do not have a Pozi screw as shown in the diagram, just what appears to be a normal bolt head like all the others. My questions concern mostly the stud issue... With the radiator out, it seems like I could leave the studs in place and simply slide the water pump off towards the front bumper? (lots of room) I am replacing all the cooling hoses, so I am willing to cut the hose that goes up from the thermostatic switch area. If this is not feasible for some reason, any good hints/techniques for stud removal? I am using a two-nut jam for my removal technique, and I have not applied any heat yet (or any Liquid Wrench type penetrants). I would sure love to avoid removing the studs if possible.
My second concern is the lack of the Pozi screw, I am guessing that this was replaced at some point in the past, perhaps when changing the pump previously? Unfortunately, I have next to no service records on the car. The odometer shows 74,000 miles.
So, what to do regarding the Pozi? I have looked at many posts here regarding water pumps, but have not found anything specific to my issues...
Thanks in advance for any clues!
John


Pozi screw should be right by pulley & fanbelt? See bolthead


V12 Water pump diagram

 

Some cars had Pozis, others didn't. If your new pump is the same as the old one and isn't countersunk for a Pozi, just use the same fastener as before.
The #15 studs remain in place. #14, if it is the stock special fastener, doesn't have a removable nut, so it must come out in order to get the pump off. But you are correct; if it snaps off, you are in a world of hurt, as it is a very long stud and is recessed. Mine didn't break, but I was lucky as some bolts and studs were rusted. I replaces most of the long bolts and studs with new ones, and also used antiseize on the threads when I installed them.

 

I recall that my present V12 didn't have the Posi-drive screw. My old V12 from years ago did. Could it be that some replacement pumps don't use it?

Cheers
DD

 

Warning, I snapped off that stud, then used a left hand drill bit to remove excess with a angle drive drill, and cleaned out with tap. Take it easy on the stud.