I am fitting a Polo radiator, the screws that hold the fan to the radiator and the radiator itself look to be self tapping, I don't have a pattern and I don't want to strip the plastic so I need to identify what fixings they should be, does anyone know the sizes and name to identify/order some?

Use a drill bit and a rule to check the diameter and depth of the mounting hole.

Then use the table here to check what size self-tapping screw you need - from memory I'd guess a no. 8 or no. 10 would be about right.

Self tapping screw sizes

Make sure you wind them in square first time to cut the thread nicely.

HTH

Edit to add...the flange head screws shown on that site help to spread the load better as well.

Also, you can probably buy a small bag of them from B&Q or Screwfix.

[Edited on 26/11/13 by nick205]

I checked the depth (not much IIRC cica 10mm?) then rummaged in my screw pot and found some fairly random self tapping bolts with corse, deep thread.
Sadly I have no idea what they came from!

I used some self tappers but don't remember the size unfortunatly but make sure they aren't too long or they could pierce the tank.

Alternativly, I believe M5 screws will go in and cut their own thread.

I tapped mines m5 and used stainless steel machine screws.

I tapped mine too and used m5 bolts

Isn't it M6 tap for polo rad? I tapped mine to M6 anyway.

My Build Diary

I did mine m6

I used M6 also and dont think I bothered to tap them, if a small lead is put on the screw it will cut its own thread in plastic and give a tighter fit, it may depend on the original hole size though but worth a try first.
Paul