Coolant Breather Line Replacement

Hi MOT on Friday and it passed no advisories. While on the ramp the guy pointed out a leak on one of the ally pipes leading up to the expansion tank. Bit of research and part number is 99610668159. Just wondered if anyone has changed this before and has some hints and tips. It looks like it will thread through from underneath. I plan the change the rubber hose on each end and poss switch to worm drive clips. Also pondering the header tank too - its a 996.2 so only mildly expensive unlike the 996.1! I think my main concern is how much coolant it will dump when I disconnect the lower end? If gallons then I’ll disconnect and bung it, get all the new pipework in and do a ‘live’ switch over! Any advice greatly appreciated!

there are a few pipes the excellent Pelican resource covers this https://www.pelicanparts.com/techarticles/Porsche-996-997-Carrera/30-WATER-Coolant_Hose_Replacement/30-WATER-Coolant_Hose_Replacement.htm Coolant flush

The Pelican parts pictures are the same as the ones in the book 101 Projects for your Porsche 911 1998-2008 996 and 997. So doing some more google research there is a vent pipe attached to the top of each rad, which join together in a Y piece (item 17 in the above diagram) then join, with a hose, to the metal pipe thats failed on mine, this in turn connects to the header tank. I expect these two vents at the high point of each rad will clear air when filling the system. I think I’ll lose the coolant in the header and what is held in the vent pipework. Hopefully it wont syphon the lot out!

Re the 101 Projects book, the author, Wayne R Dempsey is a co-founder of Pelican Parts - hence the identical pictures ;-)

Try and see if you can get a clamp on the rubber hose end if there is one - should stop the tank from draining at least.

Had a look in the engine bay and the vent pipe connects to the top of the header tank. I dont think massive coolant loss will occur. Parts ordered - I’ll report back!

So parts purchased. Ally pipe 81.68, 2 hoses that look near identical - one 16.58 other 52.70 :-0 and three hose clips 8.30. The hose clips supplied are Norma 12-22mm stainless worm drive jubilee clips rather than the spring loaded original clamps. I have these in stock so wouldnt have bothered. Car jacked up at the rear reasonably high. Disconnected the hose at the floor level and there was a constant slow trickle of coolant so bunged it temporarily. Disconnected hose at the header tank and unclipped the ally pipe (2 attachements). Ally pipe was a bit of a fight to get out. Removed the suspension brace bar which helped but it still got bent removing it. Tried for about 30 mins threading the new one in to no avail. Kept hitting the garage floor / jamming on chassis / other components. Gave up for the evening. Next steps are to A) jack the front up a bit to get some extra ground clearance and B) remove the passenger rear wheel as I almost got the pipe through via the wheel arch. I’m sure it would be easy 6 feet up on a 2 post lift. Will report back on round 2!!

Oh and most of the underbody protection removed!

So it's the vent pipe that returns from the radiators and goes into the top of the coolant tank? I'm in there today , Gen1 but must be similar. What's happened to the pipe ? Corroded or is it where the rubber hose joins? it's hard to tell from your photo.

There is a steel clip where it starts heading up over the driveshaft to the header tank - its pin holed under the clip - saltwater (UK road de-icing) and dissimilar metals me thinks. Your description is correct.

Steel clip? They're all plastic under there on mine , some of them retain 3 pipes but all plastic. That's what will have caused it.

Yep, steel clip bang in the middle of my pic with pink dried antifreeze on it.

So this has been a challenge! Spent a couple of evenings looking and trying different ways to get the new pipe in and failing. Yesterday, in desperation I called GCR for advice. Chris checked through all the parts they’d ever ordered and they’ve never done one! :-0 So this morning I disconnected the handbrake cable in the centre console and pulled it completely out of the way and the pipe went in relatively easy with a little bit of force. (Its the thinner of the two ally pipes)