Before I chowl the head up anymore and create further problems can anyone tell me which tool is used to undo the posi drive like set screw under the water pump. Or better still where I can get one. Many thanks in advance.

 

Hmm, I don't recall using anything specific on this when I did my water pump. Probably ended up using a large flat blade screwdriver.

You don't have to use a posidrive, a #4 phillips should do fine. Use an impact driver if necessary and try to find a #4 bit to be used with a socket wrench.

If you can manage, replace this screw with a torx head as you finish the job.

 

Many thanks for that. I will search on eBay now. Much obliged.

 

If you can manage, replace this screw with a torx head as you finish the job.[/QUOTE]


I don’t suppose you know the size and thread of this by any chance?

 

Sorry, it could be a #3 phillips. Measure and double check because I'm just guessing. I always think of a bigass phillips as being a #4. The width of the cut in a #3 will be around 6.5mm while the #4 will be more like 8.5mm

I think the water pump bolts are 5/16 UNC, but the best thing to do is to visit a local hardware store and thread the old screw into a nut to verify the size.

Btw I believe the manual states the torque spec to be about 27 Nm or 20 lbf. Tighten progressively in a star pattern starting from the center and going out as usual. At 27Nm I would avoid using a 3/8" drive torque wrench but use what you've got.

 

Thanks.

 

That big pozi can be difficult, I used an impact driver the type you hit with a hammer.

https://en.m.wikipedia.org/wiki/Impact_driver

The like tge idea of replacing it with a torx.

 

Brinny
This is a POZI no 3, not a Phillips head. Using a Phillips will ruin the head of the bolt. As far as I know there are no Phillips heads on the bodywork of the XJS.

 

Aftermarket water pumps aren't prepared for the set screw. I just used a normal bolt. Access is easy, no belt rubbing. Just a little fiddly. But otherwise nothing to complain about.

 

posi drive, never seen one, must be hideing under a rock

 

Take a look at any cross headed bolt or screw on your XJS!

 

Knares, anything that looks like a phillips but has a small cross through it is posidrive.

I've literally never had a single issue using phillips bits on posidrive screws. They can cam out based on the design, but I've no need to tighen that much. If all you are doing is removing it, you won't have issue with it caming out if you are using an impact driver.