In My Garage
Well-known member
Astro Pneumatic Tool 7858523 NO. 23 Radiator Test Cap (Late Model Audi, VW, Porsche)
Looking at both the factory rad cap and the Astro Pneumatic Test Cap, the threads are different in shape. Just go and buy an Audi, VW or Porsche rad cap and then compare the threads.
Pitch is right as far as I can tell, but when the screw down the AP test cap, far more force is required when compared to the factory part. The one time I tried it and not all the way either, I thought I might do some damage to the threaded part in the coolant reservoir tank.