Coolant leak

JoshApple · 08-03-2022, 02:02 PM

07 335i 134k miles, stage 2+, turbos replaced 25k miles ago, spark/coils 30k miles ago

Ive been battling a slight coolant leak on my N54 for a while now and really am trying to figure out where it's coming from because it's getting worse.

Checked the Mickey mouse flange that people were saying could be it and it seems dry around it and so I dig deeper and found this spot of interest that may help me.

https://youtube.com/shorts/pyxC6XxJnCA?feature=share

This video shows the exhaust side of my engine where you will notice a turbo stud copper nut that appears to be covered in dried coolant and also a large wet spot that appears to be right along where the heads of the motor meet. There is just coolant all over and my initial guess was my head gasket.
Furthermore, the other day while cruising at a constant speed with cruise control somewhere from (80-90mph) on the highway I noticed an abnormal engine noise that sounded like my car was misfiring or running on only 5 cylinders. Wasn't a steady, static hum like normal. Checked the codes through MHD and noticed "Superknocking Cylinder 1". Cleared the code and it hasn't came back but that weird engine noise is still there when cruising at highway speeds with constant throttle.

I don't see how my car would still be driving perfectly fine (besides the unusual noise at highway speeds) if I had a blown/partially blown head gasket. But this leaking spot seems to be right about where cylinder 1 would be which is the same cylinder I got the knocking code on.

Could they be related? Is the coolant dripping down from somewhere above? I talked to my local Indy shop service tech and hes never dealt with head gaskets on N54 and said it was very unlikely I would see an external coolant leak from a blown head gasket. Is this accurate? Is there some tests I can do to see if that's the cause or what could be the cause?

Another note, emptied my oil catch can before taking this video because I haven't in a long while and take a look at the oil residue that was settling on the bottom…

Any tips/help would be appreciated. Sorry for all the rambling

Serf27 · 08-03-2022, 06:58 PM

Highly unlikely you’d see an external coolant leak from a blown head gasket.

I have read people say the oil in the catch looks like that because the car is only driven short distances.

tlow98 · 08-03-2022, 08:06 PM

This is what oil in the catch can generally looks like in my experience.

08-03-2022, 02:02 PM	#1
JoshApple Private First Class 12 Rep 117 Posts Drives: 2007 335i coupe Join Date: Jul 2019 Location: Fenton Michigan iTrader: (0)	Coolant leak 07 335i 134k miles, stage 2+, turbos replaced 25k miles ago, spark/coils 30k miles ago Ive been battling a slight coolant leak on my N54 for a while now and really am trying to figure out where it's coming from because it's getting worse. Checked the Mickey mouse flange that people were saying could be it and it seems dry around it and so I dig deeper and found this spot of interest that may help me. https://youtube.com/shorts/pyxC6XxJnCA?feature=share This video shows the exhaust side of my engine where you will notice a turbo stud copper nut that appears to be covered in dried coolant and also a large wet spot that appears to be right along where the heads of the motor meet. There is just coolant all over and my initial guess was my head gasket. Furthermore, the other day while cruising at a constant speed with cruise control somewhere from (80-90mph) on the highway I noticed an abnormal engine noise that sounded like my car was misfiring or running on only 5 cylinders. Wasn't a steady, static hum like normal. Checked the codes through MHD and noticed "Superknocking Cylinder 1". Cleared the code and it hasn't came back but that weird engine noise is still there when cruising at highway speeds with constant throttle. I don't see how my car would still be driving perfectly fine (besides the unusual noise at highway speeds) if I had a blown/partially blown head gasket. But this leaking spot seems to be right about where cylinder 1 would be which is the same cylinder I got the knocking code on. Could they be related? Is the coolant dripping down from somewhere above? I talked to my local Indy shop service tech and hes never dealt with head gaskets on N54 and said it was very unlikely I would see an external coolant leak from a blown head gasket. Is this accurate? Is there some tests I can do to see if that's the cause or what could be the cause? Another note, emptied my oil catch can before taking this video because I haven't in a long while and take a look at the oil residue that was settling on the bottom… Any tips/help would be appreciated. Sorry for all the rambling Attached Images
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08-03-2022, 06:58 PM	#2
Serf27 Brigadier General 2856 Rep 4,324 Posts Drives: 335i Join Date: Apr 2018 Location: Sitting in a BMW. iTrader: (-1)	Highly unlikely you’d see an external coolant leak from a blown head gasket. I have read people say the oil in the catch looks like that because the car is only driven short distances.
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08-03-2022, 08:06 PM	#3
tlow98 Major General 2193 Rep 5,016 Posts Drives: 2009 E91, 2014 F15 x35i Join Date: Aug 2011 Location: Bay Area iTrader: (2)	This is what oil in the catch can generally looks like in my experience.
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