6AT 6HP19 Pink Milky Fluid

dsource · 01-09-2021, 09:06 PM

-Trans 6HP19
Recently purchased this 335xi with a slight slip. Best way to describe it, the rpms will bounce between 1800 to 2000 RPM traveling at a constant speed 50mph. Should be in 5th or 6th gear. Under high load it would shift without a problem.

I dropped the pan and valve body to preform the service, fluids, filter, mechatronics sleeves. And notice the ATF fluid was mostly a bright red, but a pink milkshake consistency started coming out. I found more of this residue inside. This means that the fluid is definitely contaminated, my first thought is that the transmission cooler has failed some sort of internal leak and mixing coolant + ATF.

I haven't found any other posts that blame the ATF Cooler/heat exchanger failed. Closest thing I've found matching the symptoms.
https://www.e90post.com/forums/showthread.php?t=1686439

Looking for confirmation of my suspicions.

See attached for pics.

Mustafa.e92 · 01-10-2021, 12:56 AM

Water does the exact same thing, any coolant loss

roadkillrob · 01-10-2021, 08:53 AM

Definitely has water in it and it can only really get in there 2 ways, coolant is mixing in (how does your coolant reservoir look, does it look like any oil has gotten into the coolant also and any milkshake on the reservoir lid?

Water got in through the vent, so car was in deep water typically for that to happen.

nyt · 01-10-2021, 10:16 AM

Also, ZF fluid is not red, and that fluid looks new aside from the contamination. Whoever sold that car likely new something was wrong.

dsource · 01-10-2021, 12:20 PM

Checked the reservoir, it appears to be just water. Which seems to add up to an internal fault in the cooler. I'm tempted to bench test the cooler, by plugging one side and applying compressed air to see if air bubbles come out of the coolant side. Scanned the transmission, no codes appeared. I'm inclined to replace the cooler. No obvious signs that the car has taken water.

Ilma · 01-11-2021, 08:14 PM

Looks to me like previous owner changed the tranny fluid with a fluid from Redline fluids.

Their tranny oil is red in colour.

ZF fluid is amber/clear and also a lot more expensive than Redline.

Other than that, the fluid looks to be in good condition.

01-09-2021, 09:06 PM	#1
dsource Private 47 Rep 56 Posts Drives: e92 335xi + miata + tdi Join Date: Aug 2018 Location: Milwaukee, WI iTrader: (0)	6AT 6HP19 Pink Milky Fluid -Trans 6HP19 Recently purchased this 335xi with a slight slip. Best way to describe it, the rpms will bounce between 1800 to 2000 RPM traveling at a constant speed 50mph. Should be in 5th or 6th gear. Under high load it would shift without a problem. I dropped the pan and valve body to preform the service, fluids, filter, mechatronics sleeves. And notice the ATF fluid was mostly a bright red, but a pink milkshake consistency started coming out. I found more of this residue inside. This means that the fluid is definitely contaminated, my first thought is that the transmission cooler has failed some sort of internal leak and mixing coolant + ATF. I haven't found any other posts that blame the ATF Cooler/heat exchanger failed. Closest thing I've found matching the symptoms. https://www.e90post.com/forums/showthread.php?t=1686439 Looking for confirmation of my suspicions. See attached for pics. Attached Images
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01-10-2021, 12:56 AM	#2
Mustafa.e92 Lieutenant 214 Rep 499 Posts Drives: 2009 bmw 335i Join Date: Feb 2020 Location: Canada iTrader: (0)	Water does the exact same thing, any coolant loss
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01-10-2021, 08:53 AM	#3
roadkillrob Major General 892 Rep 5,475 Posts Drives: 08 335i,22 X3M, 2012 C63 Black Join Date: Jul 2007 Location: NH iTrader: (15)	Definitely has water in it and it can only really get in there 2 ways, coolant is mixing in (how does your coolant reservoir look, does it look like any oil has gotten into the coolant also and any milkshake on the reservoir lid? Water got in through the vent, so car was in deep water typically for that to happen. __________________ 2025 X5 Msport 2008 E93 335i FBO 2012 Mercedes C63 Black Series Alanite Grey
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01-10-2021, 10:16 AM	#4
nyt Second Lieutenant 128 Rep 256 Posts Drives: 2010 335xi Join Date: Aug 2014 Location: Long Island, NY iTrader: (0)	Also, ZF fluid is not red, and that fluid looks new aside from the contamination. Whoever sold that car likely new something was wrong.
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01-10-2021, 12:20 PM	#5
dsource Private 47 Rep 56 Posts Drives: e92 335xi + miata + tdi Join Date: Aug 2018 Location: Milwaukee, WI iTrader: (0)	Checked the reservoir, it appears to be just water. Which seems to add up to an internal fault in the cooler. I'm tempted to bench test the cooler, by plugging one side and applying compressed air to see if air bubbles come out of the coolant side. Scanned the transmission, no codes appeared. I'm inclined to replace the cooler. No obvious signs that the car has taken water.
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01-11-2021, 08:14 PM	#6
Ilma Colonel 193 Rep 2,854 Posts Drives: 2023 M4 Competition Join Date: Nov 2008 Location: Mississauga iTrader: (0)	Looks to me like previous owner changed the tranny fluid with a fluid from Redline fluids. Their tranny oil is red in colour. ZF fluid is amber/clear and also a lot more expensive than Redline. Other than that, the fluid looks to be in good condition.
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