Small fluid leak on hot days

Drifty// · 08-28-2012, 02:25 AM

I've noticed a hissing sound, after I get out of the car on hot days. Some kind of fluid is dripping on something very hot, though only a few drops and I haven't been able to pinpoint the source of the sound. It sounds like big drops and they only sizzle for a second.

I also have had the impression I smelled antifreeze (not then, but other times), but that could just be me.

Anyway, is there any chance it's something trivial, like condensation from the air conditioning? Or is it definitely something bad?

If it were tranny fluid or power steering fluid, would it have a distinctive odor (like burning oil)? I didn't really smell anything unusual, at the time.

BTW, when I say "hot days", I mean by New England standards. Like mid 80's or 90's. I know some of you will scoff at that, but it's also humid, FWIW.

elm3 · 08-28-2012, 07:15 AM

This is just water from condensation coming from the A/C unit hitting the hot exhaust. Perfectly normal.

M3PO · 08-28-2012, 01:33 PM

If you smell anti-freeze, it may be that the coolant system is overfilled and the overflow bottle is overflowing on particularly hot days (when coolant temps are the highest and the coolant expands the most).

I've never heard a hissing sound after using my AC.

THE TECH · 08-28-2012, 01:47 PM

Keep an eye on the coolant level and see if it's changing.

BMW Fanatic · 08-28-2012, 02:25 PM

AC. As an excuse to drive your car; turn it on, AC off, drive for 30 minutes, park up, no hissing sound. Problem solved.

08-28-2012, 02:25 AM	#1
Drifty// First Lieutenant 42 Rep 310 Posts Drives: A4 quattro 3.2 MT6; E92 6MT Join Date: Mar 2012 Location: Boston iTrader: (0)	Small fluid leak on hot days I've noticed a hissing sound, after I get out of the car on hot days. Some kind of fluid is dripping on something very hot, though only a few drops and I haven't been able to pinpoint the source of the sound. It sounds like big drops and they only sizzle for a second. I also have had the impression I smelled antifreeze (not then, but other times), but that could just be me. Anyway, is there any chance it's something trivial, like condensation from the air conditioning? Or is it definitely something bad? If it were tranny fluid or power steering fluid, would it have a distinctive odor (like burning oil)? I didn't really smell anything unusual, at the time. BTW, when I say "hot days", I mean by New England standards. Like mid 80's or 90's. I know some of you will scoff at that, but it's also humid, FWIW. __________________
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08-28-2012, 07:15 AM	#2
elm3 ///M Fan 366 Rep 2,159 Posts Drives: '09 E92 M3 IB/'17 f85 X5M LBB Join Date: Sep 2008 Location: Canton, GA. iTrader: (1) Garage List 2017 BMW / X5M [9.00] 2009 E92 M3 [10.00] 2004 Yamaha R1 [10.00]	This is just water from condensation coming from the A/C unit hitting the hot exhaust. Perfectly normal. __________________ '09 E92 ///M3 Interlagos Blue,6MT,Silver Novillo Leather,CF Trim,Premium Package,Technology Package,Cold Weather Package,Premium Sound,19"Wheels,Moonroof-Toy/'17 X5M, Long Beach Blue, Executive Package,Technology Package, Lighting Package, Driver Assist, Full Mughello Red Interior, 21" wheels-Toy/'14 535i with M Sport and 19" wheels-Daily
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08-28-2012, 01:33 PM	#3
M3PO Colonel 84 Rep 2,792 Posts Drives: '08 IB E92 Join Date: Sep 2011 Location: OC iTrader: (7)	If you smell anti-freeze, it may be that the coolant system is overfilled and the overflow bottle is overflowing on particularly hot days (when coolant temps are the highest and the coolant expands the most). I've never heard a hissing sound after using my AC. __________________ 2008 IB E92 M3\| BBS \| KW \| Arkym \| Platte Forme A.G. \| Active Autowerke \| K&N \| Fabspeed \| Dinan \| Evolve-R
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08-28-2012, 01:47 PM	#4
THE TECH BimmerPost Supporting Vendor 307 Rep 13,093 Posts Drives: BPMsport 2012 E92 M3 Join Date: Jun 2011 Location: Kansas iTrader: (45) Garage List 2013 Nissan GTR [0.00] 2019 Sierra Denali ... [0.00] 1999 Nissan Silvia [0.00] 1999 Nissan Skyline ... [0.00] 1998 Toyota Supra [0.00]	Keep an eye on the coolant level and see if it's changing.
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08-28-2012, 02:25 PM	#5
BMW Fanatic Banned 135 Rep 3,293 Posts Drives: slow Join Date: Jul 2009 Location: Calgary iTrader: (11)	AC. As an excuse to drive your car; turn it on, AC off, drive for 30 minutes, park up, no hissing sound. Problem solved.
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