Does anyone know the correct size tap to use for the exhuast manifold stud hole, and the correct size drill bit to drill the hole out to? I've tried with an M10 but the biggest drill bit that will cut through it seems to be 7.5mm - the 8mm just gets stuck, sparks and starts to heat up... Maybe the 8mm is blunt?

its a 10 mm tap sounds like your drill is knackered ! start with a small drill bit say 4mm and work it up to 8.5mm then tap it out with a taper tap then a finishing tap  :y

markey mark wrote on 07. Mar 2009 at 18:01:

its a 10 mm tap sounds like your drill is knackered ! start with a small drill bit say 4mm and work it up to 8.5mm then tap it out with a taper tap then a finishing tap  :y

Thanks Mark. It's the first time I've used this type of hss drill bit at 8mm (gold coloured thing!) I'll go get a proper 8 and 8.5. Cheers mate  :y

remember to start small and work up sizes you will soon get hss bits too hot and melt tips !  :y

markey mark wrote on 07. Mar 2009 at 18:10:

remember to start small and work up sizes you will soon get hss bits too hot and melt tips !  :y

I already got up to 7.5. I thought that by then I would be able to extract the old stud, but not a hope!

chrisdb wrote on 07. Mar 2009 at 18:17:

markey mark wrote on 07. Mar 2009 at 18:10: remember to start small and work up sizes you will soon get hss bits too hot and melt tips !  :y I already got up to 7.5. I thought that by then I would be able to extract the old stud, but not a hope!

not a chance bud  ;D ;D keep going when you get the 8.5 threw it it might come out !!

That gives me hope ;D I thought it must have been welded in ;D