MonkeyVR6 0 Posted May 2, 2009 So whats the difference between the blue cap and the black cap?! I've currently got the black cap on my car and I don't notice anything odd happening, but I keep seeing stuff about a 'new' blue cap! I take it its a standard Volkswagen part? If so does anyone have the part number? Whats the difference? What am I missing out on? :? Quote Share this post Link to post Share on other sites
davidwort 0 Posted May 2, 2009 Don't worry about it, my black one was fine for 10 years don't actually think I needed to change it I just thought the seal was probably getting a bit old and perished and the new ones were cheap from GSF. The blue ones just have a slightly redesigned pressure relief valve i think. Quote Share this post Link to post Share on other sites
tedman 0 Posted May 2, 2009 best to go for a mk4 tank highly recommended viewtopic.php?f=1&t=77283&hilit=mk4+tank Quote Share this post Link to post Share on other sites
jonny-5 0 Posted May 7, 2009 Just a quick one but are the expansions tank caps (blue in my case) meant to have some sort of rubber sealing ring on them? Quote Share this post Link to post Share on other sites
davidwort 0 Posted May 7, 2009 yep, around the slightly moveable inner part, the pressure valve, 'o' ring around it. Quote Share this post Link to post Share on other sites
h5lrw 0 Posted May 7, 2009 The blue ones will release some pressure if the cooling system becomes over pressurised for whatever reason and in theory will stop hoses blowing off or the rad rupturing. Most of the guys who race the MK2's run the blue caps just incase, but under normal circumstances they make no difference. Quote Share this post Link to post Share on other sites
jonny-5 0 Posted May 7, 2009 yep, around the slightly moveable inner part, the pressure valve, 'o' ring around it. Huumm I suspect I have found the source of my water leak. Thanks very much! Quote Share this post Link to post Share on other sites
renson 0 Posted May 7, 2009 Post by jonny-5 » 07.05.2009, 14:38 Huumm I suspect I have found the source of my water leak. Thanks very much! When my seal wasn't quite sitting right the coolant blew out the side of the bottle in quite an explosive way once it got up to temp. I found out by running it up to temp on my drive by accident. Scared the life out of my because i was standing right by it at the time. I would have thought yours would do the same if the seal wasn't any good Quote Share this post Link to post Share on other sites
Richardshoes 0 Posted May 7, 2009 http://www.clubgti.co.uk/forum/showthre ... ansion+cap Quote Share this post Link to post Share on other sites
VR6Pete 0 Posted May 24, 2011 does anyone have the part number for the blue lid? Quote Share this post Link to post Share on other sites
Jon_vr6 1 Posted May 24, 2011 does anyone have the part number for the blue lid? 1H0 121 321 C - Locking cover £7.60 exc VAT Quote Share this post Link to post Share on other sites
VR6Pete 0 Posted May 24, 2011 cheers mate, just ordered from stealers! Quote Share this post Link to post Share on other sites
