Fiat Dino Forum (FDF)

The grub screw retaining the bearing on my water pump turned one and a half revolutions out then stopped. The head of the screw is starting to deform and more pressure is likely to completely strip it. I've tried penetrating oil. Does anyone have advice on how to proceed? I have a spare pump body where the screw came out just fine and another spare where the screw head was completely destroyed before I got it. Thanks, Ben.

Do you have or can you borrow an impact screwdriver?

Are you referring to the type of impact screw driver that turns/twists when you hit it with a hammer? I have one of those but the tips are all quite large 8-12 mm and the grub screw head can't be much more than 3 mm wide. If you think it would work, I could grind down a larger bit to fit. I wasn't sure the aluminum threads in the water pump would distort with impact so have been reluctant to try anything but hand pressure. Thanks, Ben.

Yes, that’s the one. I’m far from an expert, but I expect you need a lot of force to distort the threads with a screw in there. Either way, you could start of by going very easy and judge from there.

Impact screw driver sheared half the head off slotted screw leaving me nothing to grab. I had to drill out the rest and will tap and put in a larger grub screw with an Allen head and never seize to facilitate removal in the future.