[Khan535i]

Hey guys, I leaked coolant yesterday for the first time. I wasn't too bummed because to my knowledge it seems like the radiator nor the coolant reservoir is cracked. The leak under the car on the left side of the engine bay (no coolant was anywhere in the bay). From what I could see at 8 PM (the leak was done by then) with a flashlight, there was some coolant residue left under a bracket that was directly under what seems to be the Lower Radiator Coolant Hose. Is this a possibility / common source of coolant leaking in the N55. If it is, is it worth replacing the pipe at home or is going to my mechanic the move here.

I'll add more information later on when I come back home today. I still want to get under the car to see if I can see anything there.

Thanks.

[Hoa]

The upper one is more common to fail because it dealt with more heat. Lower is less common but it does happen. Most of the coolant hoses are designed to fail with the of the plastic fittings. It’s definitely something you can do at home. I’d recommend replacing the upper one as well to avoid future leaks.

[Khan535i]

Here's a few screenshots from a video I took last night.

[Hoa]

I think that’s your thermostat. It is probably not allowing coolant to flow through

[Khan535i]

So what's my course of action here?
Replace the thermostat or pipe leading to thermostat?

[Khan535i]

Just started it for a couple seconds. No low coolant sign or alert. The coolant is just dripping from this area. I think it's not leaking anymore but just dripping due to motor vibration.

[Khan535i]

Could it be the water pump?

[Trian]

How many miles? Water pump has a good percentage of failure after 70,000 miles. Both my 2012 535i (at 98,000 miles) and my current 2015 535i (at 85,000 miles) failed.

[Khan535i]

I got this motor swapped it has around 93k right now

[Hoa]

That hose typically doesn’t fail but doesn’t hurt to replace just because it along with thermostat and water pump due to age. They are all connected in that one area so I would replace those together to save future hassle.

[Khan535i]

Alright I want to get this done ASAP so tomorrow I'm going to attempt to find where the coolant is leaking from, starting from the top. My plan is to remove the radiator fan and go from there.

Wish me luck