ALH Hard Coolant Pipe question

OK so I tried to put my hard coolant pipe back on my block and I have absolutely no idea what thread/m? size the bolt is. I have an entire box of spares that I have tried but nothing will thread in.

Here is a picture of the bolt hole in ?

ETKA shows it as a M6x15, VW part number N 010 215 27

it's an M6

Thank you guys I appreciate the responces.


After trying m6's I figured out it is in fact an m7. So anyone else who runs into this. It is in fact an m7x1. I used an 1" long bolt and it work fine but it never hurts to buy long and use a hacksaw if needed to get the proper length.

Yup. M7x1.00. Same as the mk4 water pump bolts.