Radiator cap for factory five filler

[danmas]

Hi gang,

I have a pretty good size radiator test kit (had a leak on my Audi and just got one to have). The cap is the right size for pressure testing but the plunger for the cap to seal off the overflow is too big (won’t fit in the factory five neck). Anyone have a part number a pressure tester cap for the factory five neck? I did a field expedient one I put together but I want to leave it on overnight. My mockup required me holding it….

Dan

[gbranham]

Test it when you're ready for your first start. Let it come up to temp and see if you have any leaks. That's what I did, anyway. I can see how a pre-first start pressure test could be helpful, though. However, that test may prove successful, but once you get heat and pressure in your coolant system, you might find leaks that didn't previously show up.

[JMD]

I didn't pressure test mine and it was fine. Didn't have any issues immediately, and if you do it's an easy fix without the body on. Make sure to go back and tighten your clamps after the first couple of heat cycles. I had a couple loosen after cranking it up a few times, resulting in a small leak. I tightened them, checked the others and retightened them all several times. Haven't had a problem.

[cv2065]

I didn't pressure test mine either. Started it up and had to tighten up a few hoses. Silicone hoses seem to need a few more turns on the clamps than rubber. I also had filled my overflow canister up too high (3/4 full) and that caused a leak at the radiator cap, but all of it was easily fixed.