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Discussion Starter #1
So, the past couple of days I have noticed a slight scent when I park the car. Was a bit concerned but since there are no warnings I decided to ignore it. Today when I parked her I could see how there was a tiny bit of smoke coming out from under the bonnet. I popped the bonnet and removed the engine cover. And behold...there's a leaking oil line. The oil that has landed on the turbos is visibly burnt, but if I grab the oil line with my fingers I get wet from fresh oil.

DIY or BMW service first thing tomorrow morning?
 

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Discussion Starter #4
It looks like the oil line in question (the second from the left in the top photo) is the line FROM the turbo TO the cooler. The leak happens when the oil is leaving the passenger side turbo.
 

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Discussion Starter #6
So I have now diagnosed the issue further and established that the leak occurs between the rubber hose and the return pipe,
part no. 11538053161 (https://www.bmwautoparts.net/en/catalog/part/11538053161/11_5036/0) priced at £53,19
which is sealed by the hose clamp,
part no. 11151726339 (https://www.bmwautoparts.net/en/catalog/part/11151726339/11_5036/0) priced at £0,88

Look's like the clamp needs to be replaced.

The work required to complete this can be summarised as follows:
1. Remove the two heat protective jackets using the pushbuttons (est. time 2 minutes)
2. Remove the hose clamps to the two return lines from each turbo (est. time 2 minutes)
3. Remove the hose clamp connecting the return pipe to the oil pump (est. time 5 minutes)
4. Attach the new return pipe to the oil pump by securing the hose with a new hose clamp. (est. time 5 minutes)
5. Attach the new return pipe to the two return lines from each turbo by securing with two new hose clamps. (est. time 5 minutes)
6. Snap the heat protective jackets over the hoses using the push buttons. (est. time 2 minutes)

Quoted price by the BMW dealer: £1100

In all fairness, I 'm not even sure I need to replace the return pipe, my best bet is that I only need a new hose clamp.

Looks like it's a DIY after all...
 

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I'm confused. You have a very low mileage car, with a service plan, and presumably a warranty, and a problem that seems highly unusual and could be symptomatic of something else far more serious, and you are choosing to fix it yourself, at your own expense? Me no get?
 

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Discussion Starter #8
I dont have a warranty.

I believe you are now addressing two separate issues; "A" the mechanical failure in the connection point, and "B" a potential primary reason for the leak. Regardless of this specific issues frequency of occurrence there are two activities that need to be actioned upon:
1. Establish whether the primary reason for the leak is a simple mechanical failure in the connection point or if the connection point is a secondary issue.
2. Seal the leak to make sure the turbo cooling system maintains pressure.

If activity No.1 shows that the leak IS symptomatic of something else there will be additional activities (3) required. In any situation, activity No.2 must be done.

The interesting bit here is what could cause the leak. I have tried to get technical details on the oil pressure in the turbo cooling system (no success so far). The question is whether the rubber hoses that are used to connect the feed and return pipes are used as a blow-by valves in case the pressure gets too high? Seems unlikely. The more plausible reason for the hose is that a single pipe would be too complex to install, and the simplest way to connect the two pipes is a hose.

Applying my usual Occam's razor on this annoying conundrum, my guess is that the leak is the result of a worn hose connecting the pipes. The hoses are positioned very close to the hottest parts in the engine. In addition, the clamps are VERY tight. Interestingly, I found that even though the turbos on the N63 engine is not oil cooled, it uses the exact same type of pipes and hoses connected with clamps. Coolant leaks in this connection point appears to be VERY common on the N63 engine. Check this thread for interesting images and DIY tips.
DIY Leaky Turbo Lines 550i (n63)

The f10-thread includes pointers on what hose to buy, but I wouldn't go with anything but BMW parts. Looks like the hose is not sold separately, but the entire pipe is a bargain at £53.

I drained the oil last night and removed the oil filter to inspect for any unwanted agents in the oil, but the oil is clean.
Worst case scenario here is that I decide to drive her to the BMW service centre and the hose erupts completely and the turbos lose their cooling completely. She will be scheduled for an inspection (activity no.1) to see whether BMW can find something else.
 

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Um, our turbos aren't oil cooled either, are they? I thought the oil feed is for lubrication - it's at high pressure of course because of the rotational speeds involved - but the turbos and charge air are water cooled.

I may be mistaken, though.
 

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Discussion Starter #10 (Edited)
Actually, there are two systems in place to cool the turbos. When the motor runs the turbos are cooled by the oil. This is the system where I have the leak on my car. When the motor is stopped and the turbos need cooling (the oil pump is not running if the engines is not running), there's a secondary electrical system that uses water (coolant) pumped by an electrical pump. There's a fan that you can hear sometimes when you park the engine. To make a long story short, the heat built up in the turbo takes a while to get rid off, and the turbo needs cooling even after you have stopped the engine.

That is the easy short version...

I can go into more detail if you want, but you get the picture, I hope.
 

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Discussion Starter #11 (Edited)
And after some more investigation it turned out the clamp wasn't applying any pressure on the hose, thus failed to seal. I could spin the clamp around the hose with my fingers. The clamp in question is a crimp clamp which snaps into place using hose clip pliers (which I happen to have) which can also be used to remove the clamp.

I was a bit surprised to see how far into the hose each pipe end is inserted into the hose - each end is inserted about an inch. Unless you want to go ahead and disconnect the return pipe from the turbo, this becomes a bit tricky in case the hose needs to be replaced. In my case, the hose looked like brand new and it was rather obvious that the leak was caused by the weak clamp, so I decided to first replace the clamp and check for result.

After cleaning up the pipe end I fitted the pipe into the hose and tightened with a new hose clip. Ran the motor for 15min and checked for any signs of oil before I took her out on a 30min drive during which I spanked her properly. Stopped and checked the connection - bone dry. When I came back to the garage I checked again before re-attaching the heat protecting jacket, and she was still bone dry. Result!

So, activity No.1 next...
 

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Discussion Starter #13
Good news.

That saved you £1100!

:0)
Well, for know... But I dont know if I want to leave this and forget about it. Fixing a leak by tightening something will usually fail in due time. I desperately need to replace the hose. But at least I can drive her for a few weeks until I implement a more permanent solution.

The one thing that surprised me was the heat that radiates from the heat shield above the turbos. It is insanely hot. My first thought was "there's no rubber that can endure that heat without cracking". And the heat reflective "jacket" which sits around each hose is just a thin fabric with some reflective material bonded to it. I have no idea how that is able to reflect the heat.
 

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Hello

A couple of points.
These are water lines and not oil lines.
The rubber hoses of BMW will fail...I had them changed via warranty, they failed again even with the heat shields.
The heat shields get burned too.

What I did is buy samco silicon hose and replaced the OEM ones.
They should last as they can come with 600C.
Will post some photos soon.
 

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Discussion Starter #15
Hello

A couple of points.
These are water lines and not oil lines.
The rubber hoses of BMW will fail...I had them changed via warranty, they failed again even with the heat shields.
The heat shields get burned too.

What I did is buy samco silicon hose and replaced the OEM ones.
They should last as they can come with 600C.
Will post some photos soon.
That's how I understood this first as well, but the BMW garage explained that they were oil lines. Now that all made sense because they were leaking oil. If that is a water line, why is oil leaking out of it...?
 

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That's how I understood this first as well, but the BMW garage explained that they were oil lines. Now that all made sense because they were leaking oil. If that is a water line, why is oil leaking out of it...?
This demonstrates how much they know about the engine :laugh
I think they are confused by the melted heat protection and believe it's oil.

The oil supply for the turbos is underneath the turbos. The 4 lines are "2 feeding water to each one of the turbos" and "2 return of water from each one of the turbos".

You can also see in the parts diagram here -> Cooling-system turbocharger | BMW 5' F10 M5 S63N Europe
 

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Discussion Starter #17
This demonstrates how much they know about the engine :laugh
I think they are confused by the melted heat protection and believe it's oil.

The oil supply for the turbos is underneath the turbos. The 4 lines are "2 feeding water to each one of the turbos" and "2 return of water from each one of the turbos".

You can also see in the parts diagram here -> Cooling-system turbocharger | BMW 5' F10 M5 S63N Europe
My source is usually BMWAUTOPARTS. Same diagram though.
https://www.bmwautoparts.net/en/catalog/parts/11_5036/DX96214/0/0/0/0/0

An excellent explanation of the cooling systems can be found here:
F10 M5 Car Blog: Cooling
 

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Discussion Starter #18

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Here is my setup for the water cooling lines of the turbos.
Samco silicon hose which is not getting burned by the high temperatures of the turbos.

 
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