Technical Bolt size for water pump?

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Technical Bolt size for water pump?

Aug 9, 2010
Apologies for the long backstory...
My 1992 CLX had developed a modest drip of coolant from under where the water pump is, so decided to replace the water pump (and cam belt at the same time)
The 4th bolt which is in fact a nut and stud, just spun when I tried to undo it and needed me to prise the pump off a little before the nut got purchase and came off.
There was no sign of leakage through the spindle so I cleaned up the pump ready to refit with new instant gasket. Before I did, I turned the nut all the way down the stud to check it would work. It seemed fine.
However, when I put the pump back on, instant gasket etc, the nut started to spin (no purchase after about 3mm thread showing). Suffice to say I did not get to tighten the nut. All the other bolts went on OK.
So optimistically I refilled with coolant. Did some driving. Unsurprisingly the drip remains.
Before I remove and replace the pump again, I need to address the nut issue. I'd rather not attempt to replace the stud (access is limited, tools not particularly extensive). I was thinking I could replace the nut with a deeper/thicker nut to get more thread engaged and be able to tighten it effectively.
Does this sound like a sensible approach? Does anyone know the size of thread for nut I would need? Maybe use washers to pack out the existing nut?
Many thanks
Apr 27, 2011
Near the M4
Sounds like you have a stripped thread..

It is all M6 x 1.0 metric coarse as far as I am aware. 10mm spanner.. ;)

Maybe either go for a 'barrel nut'

Or a flanged nut.. like the headlamp fixings ;)
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