[David Kunitz]

Hello all!

I have unfortunately had a very troublesome cooling system lately, here is the story.

*2012 335i F30*

*Everything happened when engine was warm*

I was driving from my house to a friends place when all of a sudden I saw alot of steam rushing out the bonnet, I immediately knew I had blown a coolant hose so I switched the car off immediately, *all coolant was lost*

I saw that the micky mouse Flange had broken off, *the thought in my head being, I should have replaced that sooner,* as it was on my to do list.

Anyways I rolled back home in neutral luckily I was only 1km away.

The next day I bought a new thermostat hose which has the Flange built in and replaced it, very easy job on the N55.

I refilled and went through the coolant bleeding procedure just hoping that the issue was now resolved, but it definitely wasn't...

I went out for a quick test drive (1.5km) and half way home I see more steam, not as much but still, there was steam.
I onpend my bonnet only to see that my coolant overflow hose had split.
It isn't the original hose to start with so I just cut it shorter, rejoined it and it was fine.

Now today I start the car from cold and let it idle with a few revs to warm it up so that I could look if everything was ok.

Only once the car had reached operating temperature I now see slight steam coming from the radiator area, seems like my radiator has a leak now (video below)

After giving it a few harder revs I heard something make a pshhh noise and and a much larger puff of steam came from the left hand side of the engine bay for a few seconds.

Strangely both steam spots come and go every few minutes?

Why would every coolant hose and radiator start to burst at once?
I have only had the car for a month and a half.

My theory is that the previous owner saw a leak, put in some "coolant leak fix liquid" and now that liquid has clogged something in the cooling system causing excess pressure which is why all these components are bursting?

https://youtube.com/shorts/irNBKWZOX...vf7UbPXQMvi8va

https://youtube.com/shorts/s9jf7sPtV...fXxSErYkl4mSDJ


Ignore the microphone, it's faulty.

And the steam is alot harder to see on video!

See attached, image of water coming out top of radiator:

[thatgarrett]

Can you get some picture with the intake removed? If it’s coming from the radiator it might be the plastic end tanks separating and starting to leak, but those are on the sides and not the top and bottom. Do you have any pictures of the overflow hose you fixed? I’ve not heard of anyone fixing those before so I’d be curious to see if that’s still leaking

[David Kunitz]

Originally Posted by thatgarrett

Can you get some picture with the intake removed? If it’s coming from the radiator it might be the plastic end tanks separating and starting to leak, but those are on the sides and not the top and bottom. Do you have any pictures of the overflow hose you fixed? I’ve not heard of anyone fixing those before so I’d be curious to see if that’s still leaking

Thanks for the response!

I had the intake off today cleaning off the coolant mess, and even after having the engine running there are no leaks on the plastics or fan area, I made sure to check that.

It seems very weird to me.

See attached of non original overflow hose:

[F32Fleet]

Composites weaken from the constant heat cycling.

You have a 12 yr old cooling system after all