[18340i]

Hello
Encountered a drivetrain malfunction p10b0. Checked the intercooler reservoir and it was near empty. Filled it with 50/50 bmw coolant/distilled water) and after some brisk driving error came back. Pulled to the side and there was a puddle of coolant under the right front of the car, reservoir empty again. Main coolant fine, Temps were fine.

Car drove fine with the malfunction code, car just made no boost so just finished my track day without boost. Oil Temps, coolant temp, engine temp were all great.

Filled it up for the way back, back in boost and no code. This is a new problem today, never had problems before.

Clearly there is a leak. Where should I look? A lot of people talk about the charge cooler on f80 bimmerpost, but from my understanding, when that leaks it leaks internal, and my leak is external.

[Enabled]

Usually you get a rock strike on the front or side cooler.

The internal leak wasn't common on later cars as the intercooler was updated by BMW.

[18340i]

Originally Posted by Enabled

Usually you get a rock strike on the front or side cooler.

The internal leak wasn't common on later cars as the intercooler was updated by BMW.

Thanks for your reply!

Right front auxillary radiator is my primary suspect. Would coolant pile on the front or only the rear? Front of the rad is clean.

Have a few bent fins/bugs but no obvious large dent.

Edit: found a small circular spot of coolant on the rad. Time to work on replacing.

[Enabled]

I had a rock strike on the middle cooler a few years ago, and it would squirt it all out. Once I was driving and I saw a coolant mist coming on my windshield. I had been smelling coolant for a few days, which had been concerning.

Unfortunately the dealer had replaced the wrong radiator under warranty, so that was embarrasing for them.
I ended up replacing it myself, because a rock strike isn't a warranty issue anyways.

[18340i]

So got the leaking aux radiator fixed, error came back on a spirited drive. Reservoir low again. I'm assuming its charge cooler replacement time?

[Enabled]

No, keep filling it. They're quite hard to bleed and it will take some burping.

There's no good way to fill it without getting bubbles out, save for maybe vacuum filling.

Mine took a week of checks and refills when I replaced the front main cooler. Then it finally settled.

It's especially true if you see it foaming in the intercooler expansion tank.