Are these the same coolant cap?

[JayG]

Is the VW part 443121321 the same as the Porsche 99610644704 coolant cap?
I can get the VW part for under $10

[thstone]

In general, yes, they appear to be the same part. Or at least were at some point in time.

I say this because I did find one source that said that the VW 443121321 was equivalent to the 99610644703 (which is the older -03 Porsche part). There was no mention of an update to the VW part to be equivalent to the Porsche -04 so I am not sure what to think.

[JayG]

I'm not even sure I need to replace my cap. It is the latest ver, -04.

I know the cooling system is a closed system.
The level in my tank goes up and down a little over a few weeks. I see no drips or leaks and the trunk is bone dry. I check it when the engine is cold

I'll put in maybe 2-3 oz of distilled water and that changes the level from the min to midway between min and max.
What I did notice is a little condensation on the trunk lid above the cap. On my car there is a rubber gasket that "seals" the trunk lid to the oil/coolant fill thingy

The condensation is very minimal, no dripping, but definitely moist and you can see very very small drops of water, kind of like on a bathroom mirror after a shower

I'm thinking the cap "might" be going, dont't know

[crooster]

I think that condensation there is a pretty good indicator to try changing the cap. Heck, it's quick, easy and cheap so it's worth eliminating as a possibility.