BMW N63 Coolant or oil leaks from bellhousing area

Nicolas Technician Florida Posted   Latest   Edited  
Tech Tip
Driveability
2009 BMW 750Li 4.4L (N63B44A) 6-spd (A6HP26Z)
Coolant Leak
Oil Leak
Bellhousing
Rear Main Seal
Coolant Cover Plate

I recently worked on a 7 series with a coolant leak complaint. There was a large coolant leak coming from the bellhousing through the inspection hole. Approval was given to remove transmission and replace the coolant cover/plate and the rear main seal. After reassembling car still leaks coolant. I found out that there is a weep hole that drains directly through the cover plate in the event that water/coolant/oil fill up the valley between the cylinder heads. It’s somewhat difficult to tell if the valley is full of coolant because there is a heat shield that covers it. So if you just shine a light under the turbos it will appear dry. You could get a borescope under the heat shield to inspect valley. In our case there was a Y pipe leaking into the valley. I’ve attached some pictures that I modified to show you where the weep hole is and where the coolant Y is. This hose assembly is not that same as the coolant hoses that always leak at the T’s to the turbochargers. diag​.​net/file/f70chuzbm… diag​.​net/file/f200zs962…

I did not diag this car but I could easily see how this mistake can be made. The rear coolant cover plate is a revised part as well. I assume this means they had issues with leaks from the plate, too. Hope this helps somebody in the future. 

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Brandon Owner/Technician
Minnesota
Brandon
 

BMW addressed this in SIB 11 09 16

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Agree
Nicolas Technician
Florida
Nicolas
 

I guess we weren't the first to make this mistake. Good to know. Thanks.

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Julian Mechanic
Georgia
Julian
   

the SIB

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Lew Owner/Technician
New Jersey
Lew
 

I just did one with the leak from the same hose. Easy to miss if the leak is not that bad.

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Leon Owner/Technician
Ohio
Leon
   

I have right now on my parking lot 2012 BMW 650I with leaking coolant between engine & transmission. What have you done? Remove intake manifold and replace the plastic y-pipe. BTW it is the N63 engine 4.4l Do I have to pull both - left & right intakes out ?

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Alan Mechanic
North Carolina
Alan
 

Intake manifolds are on the outside of the V. It's been a while since I did one but if you remove the alternator you should have enough room. If you meant the n62, then the Y pipe can be changed by removing the throttle body, but they stopped making those around 2010.

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Leon Owner/Technician
Ohio
Leon
 

Thanks, it is N63 Convertable and customer use it only for summer so we are scheduled it for April. Looks like we have to replace all of the small clamps for plastic coolant connections and that 3 way hose kit.

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