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dr bob wrote: Sat Jan 24, 2026 1:04 pm
I'll add that I often use an indexing punch through the drill bushing first. That puts a dimple dead center in the end of the bolt. Deep enough to functionally flatten any angle on the fractured bolt end.
Removing the extractor sort of obviates this option though. Too tough to dimple very much if at all. It's careful work with a manual punch and a small hammer to get a center dimple and also flatten the end so the drill won't walk around.
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I'm not sure I'd ever put thread-locker on these bolts. There's just no practical way to get sufficient heat through the bolt and the water pump housing to soften it for removal, as that large aluminum mass behind it will transfer a pretty impressive amount of heat. I generally use only new steel bolts, split lock-washers, a thin film of anti-seize, and an appropriate torque driver at six lbs/ft. I try and clean all the bolt holes with a thread chaser, followed sometimes with a bottoming tap, some air then brake cleaner then air again to clear any debris. Glasses/eye protection of course.
The fastener in question is a stud on the 944, and Porsche used some form of red loctite or sealant on them, even though if memory serves, only one is open to a water jacket. Somewhere in Germany, there's a 97-y/o retired engineer gumming his morning strudel and still giggling to himself about that little practical joke.
Richey wrote: Sat Jan 24, 2026 1:11 pm
This is what I'm thinking. I measured one of the studs and it's showing the threads are about 12mm deep. I'm guessing the stud bottoms out so that's likely my depth. I've got a choice of 9mm and 12mm as a close match. I don't know that 12mm would go in flush so I think the 9mm would provide enough thread and just let the stud hang out the back of the insert.
Yea, that's the kit I bought. Mine were not as bad as yours but I was trying to avoid exactly what happened next winter when I pull the motor for a refresh.
Richey wrote: Sat Jan 24, 2026 1:11 pm
This is what I'm thinking. I measured one of the studs and it's showing the threads are about 12mm deep. I'm guessing the stud bottoms out so that's likely my depth. I've got a choice of 9mm and 12mm as a close match. I don't know that 12mm would go in flush so I think the 9mm would provide enough thread and just let the stud hang out the back of the insert.
Perhaps the lesson to be learned is to leave the water pump studs alone. They can look nasty and still do the job they are intended to do. Also, torque them to spec rather than over-torque and risk snapping one during installation. 6 ft. lbs (72 inch pounds) isn't much.
MM
michaelmount123 wrote: Tue Jan 27, 2026 10:34 am
Perhaps the lesson to be learned is to leave the water pump studs alone. They can look nasty and still do the job they are intended to do. Also, torque them to spec rather than over-torque and risk snapping one during installation. 6 ft. lbs (72 inch pounds) isn't much.
MM
You know this, but the OE bolts are not studs.... so when removing a pump that had OE bolts... boom.
michaelmount123 wrote: Tue Jan 27, 2026 10:34 am
Perhaps the lesson to be learned is to leave the water pump studs alone. They can look nasty and still do the job they are intended to do. Also, torque them to spec rather than over-torque and risk snapping one during installation. 6 ft. lbs (72 inch pounds) isn't much.
MM
You know this, but the OE bolts are not studs.... so when removing a pump that had OE bolts... boom.
?? The block comes from the factory with several studs for the water pump (4 if memory serves), along with bolts for the other water pump mounting holes...
I was also wondering about what motivated pulling these 4 studs out as they are never supposed to be removed. When ordering a new block they would come with them installled.
From what I have seen on several of these engines in various conditions the studs can rust in the case of a tired sealing between the water pump and the block as coolant slowly makes its way down the block over time. The use of studs at the bottom side of the WP rather bolts solves the potential headaches of breaking said bolts when replacing the WP if/when the lower 4 fasteners have got rusty. In my experience it is a lot less of a hassle to remove rusty nuts at the end of the studs than bolts rusted all the way through the WP body, and all that needs to be done after the WP is off is to "clean" the rust on the studs as they are/were made of a good enough steel to never rust to the point of breaking (at least theoretically). The designers chose bolts for all the other mounting points as they probably found out after hundreds of hours of lab testing that gravity caused coolant to never seep upwards and that this lowered significantly the risk for the other, upper mounting points to get rusty.
This is a case where German engineering, which I agree is sometimes puzzling, was not completely stupid.
Because I'm in the process of restoring the car. Part of that is replacing worn things like seals, hoses, gaskets, and rusty hardware. Everything I read and watched before doing this said it was Loctite Red but nothing said just leave them alone no matter how bad they look.
The reason for replacing them is that the anti-corosion plating was gone. Re-using them was just kicking the can further down the road but likely making it worse as time went on. I'm in there and I'd rather address anything I can now instead of later.
Thom wrote: Wed Jan 28, 2026 1:34 am
I was also wondering about what motivated pulling these 4 studs out as they are never supposed to be removed. When ordering a new block they would come with them installled.
From what I have seen on several of these engines in various conditions the studs can rust in the case of a tired sealing between the water pump and the block as coolant slowly makes its way down the block over time. The use of studs at the bottom side of the WP rather bolts solves the potential headaches of breaking said bolts when replacing the WP if/when the lower 4 fasteners have got rusty. In my experience it is a lot less of a hassle to remove rusty nuts at the end of the studs than bolts rusted all the way through the WP body, and all that needs to be done after the WP is off is to "clean" the rust on the studs as they are/were made of a good enough steel to never rust to the point of breaking (at least theoretically). The designers chose bolts for all the other mounting points as they probably found out after hundreds of hours of lab testing that gravity caused coolant to never seep upwards and that this lowered significantly the risk for the other, upper mounting points to get rusty.
This is a case where German engineering, which I agree is sometimes puzzling, was not completely stupid.
