[alexjustdoit]

'13 - 335i - N55

Had the banjo bolt for the coolant feed (aftermarket turbo and banjo size) replaced as it was leaking coolant - it has now been almost exactly two months since the new banjo was put in and I got a low coolant warning on the car again. Up til now, visually the tank level has been, and still seems to be, the same, but I topped it off (it seemed like I would add some then the level would go back to where it was, added some more, til I got to the line).

So i'm wondering... is it possible somehow that the replacement banjo is not leaking and something else caused this like maybe tech didn't bleed/top off coolant when banjo was replaced, and somehow I didn't get the warning til now? Is that even possible? Cause otherwise the replacement banjo is a dud OR the sensor is malfunctioning (or I guess the tank is leaking).

I know the system is sealed, but Ive heard some say it shouldnt need topping up and I've heard some say that slight top ups here and there are expected (tho not sure what would be causing the coolant loss) so clarity on that would be appreciated.

Secondly, if I just keep topping off the coolant, can I get by for a while? How big of an issue is this?

The work is theoretically under warranty by the shop but it is an aftermarket turbo and a non OEM sized banjo bolt so...

[F32Fleet]

White smoke?
Sweet smell in cabin?
Oil in coolant tank?
Coolant under oil cap?

If no to all pressure test and dye test for hydrocarbons in coolant.

[alexjustdoit]

Originally Posted by F32Fleet

White smoke?
Sweet smell in cabin?
Oil in coolant tank?
Coolant under oil cap?

If no to all pressure test and dye test for hydrocarbons in coolant.

No to all those, tech pressure tested when the banjo was replaced but may have to again...

Is it normal to have to top up coolant periodically? I've heard for some models that it is normal, so long as its not too much, but then again some say its not normal.

[F32Fleet]

Originally Posted by alexjustdoit

No to all those, tech pressure tested when the banjo was replaced but may have to again...

Is it normal to have to top up coolant periodically? I've heard for some models that it is normal, so long as its not too much, but then again some say its not normal.

I myself have never had to add coolant.

[alexjustdoit]

Bit of an update... the level does not seem to be going down, but the car keeps alerting me to refill coolant. The first time I added a bit, I was on a slant, and its actually slightly overfilled now, but still it tells me to add more. I'm thinking it must be a sensor issue? But I have heard the sensors are not really prone to failure at all, as they are very simple. Could it be a pressure issue? I tried to bleed it, but I didnt hear the pump come on for more than a few seconds so even tho I tried twice, I'm not sure it did anything...

[BashShah]

It's the Coolant reservoir level sensor.
You need to replace the whole reservoir bottle.
went through this in 2019.
after replacing, no issues.