what size are 10mm bolts (oh yes :-) )

a 10mm flange head bolt will generally have an 8 mm thread.

tvm

I could be wrong, but 4x M8 bolts just for a waterump? They may be M6 threads. As I said, I could be wrong as I have indeed come across those that MrC mentioned. Take one of the remaining bolts to a fastener place or motor factors? JB

Jeez. Get a vernier caliper (or even a bloody ruler) and measure the two you still have rather than ask such a pathetic question on here.

... and don't lose it !!!!

A really quick and easy measure available in the average tool box is to use an open ended spanner, keep going down in sizes till you find one that closely fits over the threaded bit. Taking an existing bolt to a car shop or a motorbike shop is probably the simplest way for most folk to get a suitable replacement.

Hey Bozzo-censor, it's people like you that put people off using NG's. (But not me). I see thickos like you all the time. For the past

Oh I forgot to say to Baker

Yes s*it for brains. It's not just the diameter. It's that plus the thread pitch which any reasonably competent h*mo sapiens should be able to measure without having to ask other people to guess based on just the bolt head size which is a complete variable.

Hey, just get an older brother or sister with a more fully functioning cerebellum to do it for you. You clearly don't have the wit to do it for yourself.

Nah, M8 is usually 13mm head. 10mm head would usually be M6. M5 is 8mm head.

not when they have a flange, they usually have a reduced head diameter, your figures are correct and standard for ordinary set bolts.

I wondered about that too as a 10 mm spanner fits a 6mm bolt head here. But not sure about 'flanged head'.

So even less reason to ask what thread it is with just the 'a spanner I have sort of fits it' information.

Why not remove one of the bolts you haven't lost and give the TPI and diameter? Or just pop to your local dealer for maker's spares?

At a guess size 42 and a bit

You're welcome