There's a coolant leak that's coming from either the side or the rear of the motor. Does anyone have any suggestions on what it could be? I plan on lifting the car tonight to see if I can find the source.
Pure speculation, but look at all the hoses on coolant pumps (I think your car will have 2 or 3 electric ones and the one on the engine), along with all coolant related solenoid valves (changeover valve) and "T" connections.
Inspect the coolant connections for the turbo charger also. Your car has enough miles on it they may an issue.
Thank you for the suggestion.
I got her a car and look but really didn't see anything stick out. The crazy thing is once I add coolant to the reservoir, it immediately leaks out from wherever the issue is. It looks like it's leaking from above the oil drain pan, but since I can't really see it, I can't tell for sure.
It's not from the expansion tank, unless there's another one in the rear of the engine. I did take off the engine cover, but still couldn't see anything. The oil pan has a formed cover around it and it blocked my view from underneath. So basically I couldn't see any on the rear coolant connections.
I'm adding coolant to the larger expansion tank (radiator expansion tank). The smaller expansion tank still had visible fluid
I'll try and get pictures tomorrow.
Yes, it leaks as soon as I pour in the fluid with the engine off.
Do you think this hoses you listed are easier to spot from the top or underneath?
Was the Turbo coolant lines TSB/SIB performed on this car? If so, the very likely culprit is a leak from a failed clamp on the hose marked #2. Very easy to check by simply taking the engine cosmetic shield off (pops out) and either running the engine or pressuring coolant tank with a pump. Mine included, there have been several reports of this failure at the same exact spot so its worth a check. Due to the location, it is possible to feel that the leak is from the rear underside of the engine even though coolant is running off the top and through the V valley of the engine.
This thread has some pics for orientation.
I have a 2017 750i xdrive. Almost 63k miles, does not have extended or 3rd party warranty. Recently took it in to BMW service center and the guy said afterwards that the turbo coolant lines are leaking and it would cost around 6K to replace. Did some reading and saw this is common and read about...www.bimmerfest.com
I have time today and can investigate more.
One thing I noticed is when I added the coolant directly to the larger expansion tank it would leak out immediately towards the back side of the car. The smaller expansion tank may not have loss any fluid, or as much fluid. How are those two tanks related?
And if I have to replace any of these lines are on the back side of the motor, is this achieved by top access or underneath the car access?
I think you will need to pinpoint the leak first. Some would need to be replaced from the bottom (like the transmission oil cooler). But once you figure out where the leak is, you can look it up in ISTA to see the recommended procedure for replacing it.
Also, from what I can tell, the small (high temperature) tank cooling circuit and large (low temperature) cooling circuit are separate cooling loops. As I understand it - the high temp circuit cools the cylinder head. There may be times when certain valves are opened and the coolant mixes between the two, but I am not sure.
Just for clarification, is this what your refer to the larger (low temperature) tank is #1 => https://www.realoem.com/bmw/enUS/showparts?id=7E23-USA-09-2015-G12-BMW-740i&diagId=17_0988
Here are a few updates and questions:
1. there are no visible leaks from the transmission cooler. This would be the easiest fix, but oh well.
2. There is a visible leak I can see from above and underneath the car (see image), however, I do not believe this is the main leak I'm seeing. Mainly because the leak bigger leak is running over the engine oil pan. On the image, there are 2 items marked if anyone can tell me what they are. This will need to be fixed as well.
View attachment 1081845
3. I need to remove the wipers in order to free up room. ISTA states I need a special tool (see pic) or I risk breaking the wiper console at a predetermined breaking point. Any advise on removing the wipers without the tool?
View attachment 1081846
4. How is this clip opened? I messed around with it a bit, but couldn't figure it out.
View attachment 1081847
5. If I remove the air intake header (see pic) will that open up that area more so I can see the hoses that are more on the rear of the motor?
View attachment 1081848
6. As I stated above, the leak comes from above the oil pan. I was not able to see the leak under the car. The hose diagrams are not that great, but what are the possible hoses that are back that far? Under the air intake header, there is an auxiliary coolant pump, I'm wondering if the leak is somewhere there.
I'm sure I'm forgetting something. Any help would be much appriciated.