gdean2323

The black one is 996-106-447-01
The blue one is 996-106-447-00

Now I know that the black one has better pressure relief capabilities, but does anyone know the specifics? They look like they are mechanically identical. Was the 01 cap just defective or am I missing some minor difference?

1999Porsche911

I still have the orginal blue cap and have no problems on my 99.

Tool Pants

I have never seen a black cap. Can you filp them over and take a picture of the part numbers.

djantlive

which cap is this?

Armando Ramirez

Radiator cap right?
They had problems with the first one leaking, I think it was releasing at too low a preasure out spewed your green go go juice.....if that pic is not the radiator cap...my statement is still true..they replaced mine after my second tank went bad and the cap started leaking....

gdean2323

Yeah these are radiator caps (sorry) the part numbers are in my first post. When I ordered the replacement cap (the black one) I expected it to look a lot different. I guess I was hoping to see how it solved the problem. However they look very similar. I guess its a subtle difference. Anyway, no more white coolant droplets all over the place and I can stop checking my coolant level.

For those of you who haven't replace your cap, I was told that this was a no brain purchase to prevent damage to the coolant reservoir. If you notice white salt-like droplets on the engine components surrounding the coolant resivoir and/or white build up around the cap itself, I'd order one.

Bijan

I just had a replacement cap 996 106 447 01, the replaced one had same number with slight white deposits at the base and very small coolant level drop. Both were blue

Tool Pants

Strange that your .01 cap is black and not blue. I put in the .01 cap in November and it was blue. We had a Cayman tech session last week and the Cayman has the .01 cap and it was blue.

Since the 1997 Boxster there have been 3 versions of the cap and I have never seen a black cap.

Your black cap looks identical to my 996 106 447 01 cap except mine is blue and yours is black.

Maybe Porsche recently switched to black replacement caps. Next time I'm at the parts department I will take a look at the caps on the shelf.

Still would like to see a picture of the other side of the black cap in case they do not believe me.

Pic from Geoff.

gdean2323

The black cap is not a genuine porsche part, so it does not have the part number on the top. It was what p*lic@np@rts.com sent me when I ordered the part #996-106-447-01. I was surprised to see the 3rd party coolant cap, hence the reason for me wondering about the difference. However, it looks like the black cap is identical to the 01 cap in the above picture.

regardless I will take a picture of the top of the cap for everyone anyway.

I am little confused by the coolant cap (which is ironic because coolant caps shouldn't be confusing). However, let me explain the sequence of events.

1) Bought the car drove it home (1000 miles)
2) While driving home I notice what appeared to be coolant spray on the intake, and coolant residue around the cap itself. More to the point the coolant level appear slightly low.
3) I Refilled the reservoir to the appropriate level, and ordered the black cap.
4) Whilst waiting for the black cap, I kept an eye on the coolant level, added a little bit, but not much.
5) Black cap came in yesterday. I put the cap on and drove around town a little.
6) Today (with the black cap) I drove to work (50 miles), and took an hour long cruise during lunch. Around 2PM I noticed a lot (think river) of coolant on the ground. It had indeed spewed almost the entire coolant resivoir all over the ground. The reservoir indicated a coolant level slightly below MIN. At no point had any coolant appeared during the other drives (trust me I checked it).

So needless to say, I a little mystified about what is happening. My only, and somewhat sorry, hypothesis is:

The blue cap was over pressurizing the coolant system, giving it the appearance of being low. By continuosly refilling the reservoir, I overfilled the system. Then I switched to the black cap which, properly relieved the over pressured system, causing the excess coolant to spill onto the ground.

This seems pretty far fetched and seems to be hinged on some assumptions that I am not sure about.

1) Does coolant compress? (water does not, but water is rather unique)
2) Does the coolant system behave in a manner that would allow this to even be possible? Specifically, can some part of the system reamain at a higher pressure when the coolant cap is removed for a short period? Would an overfilled coolant system discharge more than the amount it was overfilled?

gdean2323

I was under the impression that it was releasing at too high a pressure, hence damaging the reservoir.

Bijan

Changing the coolant cap was a good start.
Expansion tank micro cracks with age is another known issue with 996/Boxter, there will be a number of search results here
Renntech has a DIY artcle
http://www.renntech.org/forums/index.php?showtopic=8024