[Mosaud1998]

I opened my coolant res. to see the color of my coolant since it was flushed 3 years ago at 64k miles (I am sitting at 72k miles right now) and noticed brown looking liquid. When I push the float down and look directly below the float, the liquid is blue. When I look at the back end of the res. there's that brownish-colored liquid. The OFHG was done around 67k miles. No oil dripping or smell from anywhere. Maybe the coolant is just dirty?

[Mosaud1998]

Update: I just dipped a paper towel in that "Brown liquid" and the paper towel came out to be BMW OE blue coolant.

[gbalthrop]

If you had oil in the coolant reservoir, you would PROBABLY also have coolant in the oil, particularly if the OFHG replacement were the cause of the issue.

Since you don't know the precise history of the car BEFORE the last several years, there MAY be some residue related to an earlier problem which is no longer present. I would suggest checking BOTH the coolant and the oil as follows:

1) Use some type of "Swab", such as a dowel with clean paper towel or cloth wrapped around the end to wipe the area that appers "brownish". Remember that the COLOR of the Coolant/ Anti-freeze is NOT important, but rather the chemical characteristics. Ethylene Glycol is the primary ingredient and either Green, Greenish-brown, Yellow, or BLUE ethylene glycol is OK, as long as it has proper "corrosion-inhibitors" which most any ethylene glycol such as Prestone has. You're concerned with motor oil in the coolant.

2) With front wheels on ramps, or front jacked and supported by stands, remove the front splash shield and lower radiator cover. Open the radiator drain tap on left side beneath radiator. Make sure you use 19mm combo wrench to prevent sleeve into which P4 Plug is inserted from turning as you "UNscrew" the P4 drain plug. Drain just a small amount of coolant from the radiator and inspect in clear container such as a measuring cup, for any suspended matter such as oil, dirt, rust, scale.

3) Open Oil Filler Cap on Engine Cover, and (a) use a bright light (or endoscope if you have one) to inspect for any white, milky goo anywhere under the valve cover where you can see it. Inspect the filler cap itself, and/or use a Swab similar to (1) above

You have a "relatively-low-mileage" E9x compared to most on this forum, and you may be "seeing things" or suffering from that dreaded disease: "AutoHypoChondria". Try to think of your car as a collection of metal & plastic parts, held together with nuts & bolts, and WHATEVER you do, don't give IT/HER/HIM a NAME!

Seriously: It's better to be vigilant, try to learn how to spot issues EARLY, and how to prevent serious issues. Trying to find a proper middle ground between OCD (Obsessive-Compulsive Disorder) and OTL (Out-to-Lunch ;-) is always hard.

Please let us know how it goes
George

[Vivek.]

Looks like the inside of the rad is brown. Normal condition, nothing to worry about. Coolant on the paper towel looks perfectly fine.

[Mosaud1998]

Originally Posted by gbalthrop

If you had oil in the coolant reservoir, you would PROBABLY also have coolant in the oil, particularly if the OFHG replacement were the cause of the issue.

Since you don't know the precise history of the car BEFORE the last several years, there MAY be some residue related to an earlier problem which is no longer present. I would suggest checking BOTH the coolant and the oil as follows:

1) Use some type of "Swab", such as a dowel with clean paper towel or cloth wrapped around the end to wipe the area that appers "brownish". Remember that the COLOR of the Coolant/ Anti-freeze is NOT important, but rather the chemical characteristics. Ethylene Glycol is the primary ingredient and either Green, Greenish-brown, Yellow, or BLUE ethylene glycol is OK, as long as it has proper "corrosion-inhibitors" which most any ethylene glycol such as Prestone has. You're concerned with motor oil in the coolant.

2) With front wheels on ramps, or front jacked and supported by stands, remove the front splash shield and lower radiator cover. Open the radiator drain tap on left side beneath radiator. Make sure you use 19mm combo wrench to prevent sleeve into which P4 Plug is inserted from turning as you "UNscrew" the P4 drain plug. Drain just a small amount of coolant from the radiator and inspect in clear container such as a measuring cup, for any suspended matter such as oil, dirt, rust, scale.

3) Open Oil Filler Cap on Engine Cover, and (a) use a bright light (or endoscope if you have one) to inspect for any white, milky goo anywhere under the valve cover where you can see it. Inspect the filler cap itself, and/or use a Swab similar to (1) above

You have a "relatively-low-mileage" E9x compared to most on this forum, and you may be "seeing things" or suffering from that dreaded disease: "AutoHypoChondria". Try to think of your car as a collection of metal & plastic parts, held together with nuts & bolts, and WHATEVER you do, don't give IT/HER/HIM a NAME!

Seriously: It's better to be vigilant, try to learn how to spot issues EARLY, and how to prevent serious issues. Trying to find a proper middle ground between OCD (Obsessive-Compulsive Disorder) and OTL (Out-to-Lunch ;-) is always hard.

Please let us know how it goes
George

I've got a big ol folder full of service history from the PO

I already tried number 1 and number 3. But, instead of using a dowel I used a paper towel and dipped it in this so-called blue magical liquid and the paper towel came out as BMW OE Coolant Looked inside the engine and nada nothing but clean fresh oil and shininess

I guess I have a severe case of snooping around my engine bay late at night instead of snooping in the kitchen looking for food

As always, thank you for your help George

(I'll probably flush the coolant out sometime in April once my oi change is due)

[mweisdorfer]

Originally Posted by Mosaud1998

I opened my coolant res. to see the color of my coolant since it was flushed 3 years ago at 64k miles (I am sitting at 72k miles right now) and noticed brown looking liquid. When I push the float down and look directly below the float, the liquid is blue. When I look at the back end of the res. there's that brownish-colored liquid. The OFHG was done around 67k miles. No oil dripping or smell from anywhere. Maybe the coolant is just dirty?

It would be frothy

[fgpalmer71]

Similar issue here. Only there was nothing brown looking floating in the reservoir. The float snapped and when I inspected it there was black sludge on the bottom of it. Coolant was fine.....no visible leaks from the OFHG or cooler gasket....drained a smidge from the radiator, it too was perfect. Chalked it up to a past issue and bought a new reservoir and coolant hoses. I plan to overhaul the cooling system this spring just to be safe. I've read that the sludge that can be left behind from a leak deteriorates the plastic fittings at an extremely high rate.

[Mosaud1998]

Looks like I was just seeing things . The first picture is coolant I took from the bottom of the reservoir and the second pic is coolant from the top of the reservoir. No "brown" looking fluid or anything.

[POBEP]

Originally Posted by Mosaud1998

Looks like I was just seeing things . The first picture is coolant I took from the bottom of the reservoir and the second pic is coolant from the top of the reservoir. No "brown" looking fluid or anything.

OCD recommendation:
Dispense the syringe content into a glass cup and let it sit overnight.
if it looks the same next day - you are all good.
if there is any oil - you'll see a oil film atop on the edge of the glass

OTL option:
Just by looking at your pics I would say there is nothing to worry about.

[POBEP]

Mosaud1998 for reference, this is what my contaminated coolant looked like (10 years, 90K miles).
Note discoloration and oily film atop.

[Mosaud1998]

Originally Posted by POBEP

Mosaud1998 for reference, this is what my contaminated collany looked like (10 years, 90K miles).
Note discoloration and oily film atop.

Yeah, that's what mine sorta looks like in the res. But the coolant is only 3 years old

[rapter]

Did you ever get to the bottom of what was causing the brown liquid?

I am starting to see the same thing.

[Mosaud1998]

Originally Posted by rapter

Did you ever get to the bottom of what was causing the brown liquid?

I am starting to see the same thing.

I ended up doing a coolant flush. The coolant was just dirty if I remember correctly. I sold the car 2 years ago.

[rapter]

Originally Posted by Mosaud1998

I ended up doing a coolant flush. The coolant was just dirty if I remember correctly. I sold the car 2 years ago.

We flushed the coolant 2x using the dealer level flushing tool.
The darkness came back in 500km.

Was hoping you got to the bottom of it.