those fittings can be PITA sometimes. you should be able to remove them by hand without tools though. It helps to push the hose further onto the fitting, then squeeze the clip, then pull the hose off. If you try pulling at the same time as squeezing it doesn't want to work. Pushing it on more is the key. Try not to use a bunch of force when pushing pulling the hose as that can just bang up the locking clip thing and make it worse. The special tool helps, you still need to push then pull though. Maybe give it a little twist as well?

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Olympic Peninsula, WA, USA
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2005 Mini Cooper 100k, British Racing Green/Silver-Black
04/2002 4.6is 140k, Silver/Black-Alcantara *FOR SALE*
1989 325iX 270k, Diamond Black/Black
1984 318i 370k *SOLD* (First Bimmer)
Honorable Mentions: '71 2002, '87 325, '90 325ic, '92 525it, '93 325i, '94 530i