Just wondering if anyone else has had to replace their radiator fluid cap before. I think my cap has gone bad, when I squeeze the radiator hose I can hear air coming out of where the cap is tightened. I've tried tightening the cap as much as I can and I still heard noises coming from the cap. Also, I've been losing tiny amount of coolant at a time and I know it's leaking from the cap because I see little blue streaks around the cap. I've finally started to try some silicone sealant around the edge of the cap threads but I don't think that's even working. I have examined the cap threads and O-rings but I can't find anything wrong with it. Any suggestions?
Originally posted by Brian325i+Oct 22 2004, 06:42 PM--><div class='quotetop'>QUOTE(Brian325i @ Oct 22 2004, 06:42 PM)</div><div class='quotemain'><!--QuoteBegin-Casey3561@Oct 22 2004, 06:53 PM I would say replacing the cap would be logical. Is the hose nice and solid, or is it a bit mushy?
It's mushy but that's because the air is seeping out....is it supposed to be solid?
radiator hoses shouldn't actually be soft to the touch - you can usually when they're about to fail when they're a little swollen in places - when they get mushy they're liable to fail any time.
have you ever been to the BMW dealer? I believe, but cant guarantee that there is a recall on some radiator caps. Call you local BMW and ask them if there is one, and whether your car has gotten it changed. I went for a code delete (back in the day) and they changed the cap at no charge due to a safety recall...might be the case with you. as for the hoses, supark is right. if they are soft, its time to change. make sure you bleed the air out of the system before it turns into a bigger problem though.
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OK, Brian. Stick your left arm out and make a fist. Squeeze your left forearm with your right hand. Assuming you have some muscle there, it'll feel a lot like what a hose is supposed to feel like- minimal give, but yields slightly to firm pressure.
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NOOOO!!! ALL OF YOU! the radiator cap is designed to breath. On BMWs the expansion tank (coolant resovoir) attatches directly to the radiator and therefore "looks" as one; it isn't though. The expansion tank needs to breath so that you cooling system doesn't over-pressurize. If you're having cooling system problems it can be anything from a cracked head to a loose hoseclamp. Just remove the bleed screw on top of the radiator, fill up your coolant resovoir, tighten the bleedscrew back in, then slowly drain the excess coolant to the line on your resovoir using the large plastic knob looking screw at the bottom of the resovoir (commonly they're colored). If your coolant keeps running low and you can't figure out where it's going, you may have a more serious problem (a symptom of a cracked head is white-cloud vapor from exhaust).
Damn are you serious? I've been filling up my resevoir to the very top...I just assumed stuff was leaking because I saw dried coolant streaks from the cap...but now I realize that there is a little line labeled "kalt/cold" on the resevoir. My collant had gone down to that level. But if that's the case that the cap needs to breathe...then my hoses won't be firm.
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