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#4677105 - 02/24/18 11:04 PM 2011 BMW 328i - coolant leak
Ndx Offline

Registered: 04/04/08
Posts: 1830
Loc: IL
Hi Guys,

I'm trying to find coolant leak... Has anyone used the UV dyes ?
Do I just add it too coolant ?, Do I have to flush system after ?

Are those dyes universal or coolant specific ? If specific any recommendations for Bmw coolant.

Thank you

#4677190 - 02/25/18 02:35 AM Re: 2011 BMW 328i - coolant leak [Re: Ndx]
rooflessVW Online   content

Registered: 12/24/11
Posts: 4095
Loc: North Carolina
You simply add the due to the coolant, however;

An external coolant leak should be fairly obvious even without a dye.

How much are you losing? If you can't see crusty coolant trails it may be the heater core or internal.
"Zed's dead baby, Zed's dead."

#4677288 - 02/25/18 07:30 AM Re: 2011 BMW 328i - coolant leak [Re: Ndx]
Audios Offline

Registered: 11/19/11
Posts: 889
Loc: Lyndhurst NJ
Pressure test the system to find leaks, the coolant is already blue. Ive been having a run on radiators and expansion tanks on the E9x's lately. Get it up in the air take the panel off and look from the bottom.
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#4677325 - 02/25/18 08:07 AM Re: 2011 BMW 328i - coolant leak [Re: Ndx]
Ndx Offline

Registered: 04/04/08
Posts: 1830
Loc: IL
It's leaking on outside but I think only while driving or super hot.
I see drips on driveway but even that does not help pin point....

I had oring on filter cap fail and spray everything around so that does not help lol it's mess there ... I don't want to wash engine in winter ...

Thx guys

#4677426 - 02/25/18 09:53 AM Re: 2011 BMW 328i - coolant leak [Re: Ndx]
andyd Offline

Registered: 09/25/04
Posts: 7167
Loc: Marshfield , MA
Later model BMWs plastic cooling parts have a rising failure rate as the car approaches 100K miles. The old, last 30 yrs plus stuff, wasn't recyclable enough.
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#4677430 - 02/25/18 09:57 AM Re: 2011 BMW 328i - coolant leak [Re: Ndx]
Lolvoguy Offline

Registered: 02/06/14
Posts: 2350
Loc: Canada
Doing a cooling system "overhaul" once every 80k miles, seems to be very common on these cars as complete kits are readily available:
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#4678515 - 02/26/18 09:15 AM Re: 2011 BMW 328i - coolant leak [Re: Lolvoguy]
jeepman3071 Offline

Registered: 04/15/10
Posts: 4220
Loc: Storrs, Connecticut
Originally Posted By: Lolvoguy
Doing a cooling system "overhaul" once every 80k miles, seems to be very common on these cars as complete kits are readily available:

That's for the E46, the OP is talking about an E90 generation car.

OP: How many miles on the car? Check the plastic coolant hose connectors for white residue or drips. The o-rings on the connectors like to leak and the plastic hoses crack. My GF's E90 cracked the coolant hose with the sensor on the passenger side. The hose cracked right where the sensor mounts onto the connector.

Also have you replaced the oil filter housing gasket yet? The gasket gets brittle over time and can cause coolant and oil to mix. Like stated above also check the expansion tank and cap for white residue. The tanks crack and the caps fail, causing them to lose pressure and leak.
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#4678608 - 02/26/18 10:55 AM Re: 2011 BMW 328i - coolant leak [Re: Ndx]
Alfred_B Offline

Registered: 05/12/15
Posts: 1968
Loc: America
Probably a hairline crack on the coolant expansion tank if it only happens when super hot. E46 has that issue, I thought they had fixed it for E90.

#4678868 - 02/26/18 03:30 PM Re: 2011 BMW 328i - coolant leak [Re: Ndx]
Trav Offline

Registered: 11/20/06
Posts: 18909
Loc: MA,
The dye works well with a UV light, get one for coolant (dexcool has a different one) run it and pressurize it then start looking.
I would bet its from some plastic part that is cracked on these.
ASE L1, Master. Deutsch Meisterbrief.

#4679275 - 02/26/18 09:48 PM Re: 2011 BMW 328i - coolant leak [Re: Ndx]
antonmnster Offline

Registered: 03/29/10
Posts: 802
Loc: Minneapolis
My radiator developed a slow leak in a corner around 120k. be THANKFUL you don't have a 335. That job brought me to tears - it's like the assembled the unibody around the radiator.

Pay attention to where the puddle is when you park it. Is it right at the front? Driver side? Passenger? Those can be big clues. Otherwise don't be afraid to get under it and pop the splash shield off. Take a good look around the water pump, the big electric pump hanging off the passenger front corner of the block. Odds are highest that it's the pump. Just a heads up, it ain't cheap, and it ain't easy to get to.

#4679526 - 02/27/18 09:43 AM Re: 2011 BMW 328i - coolant leak [Re: Ndx]
mightymousetech Offline

Registered: 04/03/17
Posts: 1444
Loc: Ontario, Canada
On an E90, first thing to check is the expansion tank and the water pump.
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