[F30jamess]

I have a 2017 bmw 330i and I just did a random check on bm3 to check codes cause my car was acting a little strange, I didn’t have a cold ac and my car stopped accelerating as fast when I got to around 100 mph and the car felt the same in comfort and sport+. this code came up 20A201 (charge air cooling system) did some research then checked the coolant I didn’t get a low coolant warning on my main tank but the second one for the heat exchanger was low and I can see that I have coolant on my fan and my chsrgepipe as in the pictures I just don’t know if its my main radiator or the actual heat exchanger because it’s bleeding through out the main radiator. I have pressure in my main hoses and I don’t have pressure in my heat exchanger hoses I have the car up to operating temperature every time I drive and it doesn’t overheat so I just want a way to confirm the heat exchanger is leaking before taking things apart.. I don’t see it leak at idle even after 5-10 minutes but I know there’s a leak. If anyone had this issue and could help me resolve it I’d appreciate it.

[scubajim]

there is a line on top of the radiator...dont recall the name but it's a common failure point. It might be under a cover but it runs left to right.

[erickonphoenix]

The coolant pooling up on the shroud is a pretty pointed indicator you may have a heat exchanger leak. Rare but it can happen. The fan is collecting coolant then when you stop the residue leaks down into the shroud.

I'd pull all the lower radiator belly pan panel out, run it then get underneath an carefully look over it with a light.

If you need to replace the heat exchanger be advised (depending on mileage) while the system is discharged you may want to also replace the coolant hose to engine flange to the metal version. CRP-CHC0609.

FYI, I overhauled my entire cooling system at 100k miles. That was hoses, thermostat, water pump, and the flange. I did not change the heat exhanger.

[F30jamess]

I’ll check everything out more when I have an off day from work I wanna be sure a rock hit my heat exchanger but now I remember I hit a deep deep pothole on accident and I knew it was there but I felt it through the steering wheel and I was praying my suspension was okay but I think maybe I could have hit the bottom of the heat exchanger and did some damage there I’m not sure but I’ll do a more thorough look through in a day or 2.

[F30jamess]

My main coolant tank was also low today which is strange because it hasn’t went low this whole time idk if one is low the other will try to fill it in idk if it’s a shared system in any way but I still didn’t over heat and then I kinda let her open up on the highway cause a mustang wanted to fly by me so I flew by him 🙂‍↕️

[erickonphoenix]

Our Honda Accord had a rock penetrate the heat exchanger, so it can happen. Potholes typically just wreck the control arm bushings and the upper strut mounts. You could also bust a strut but that's not especially common either.

Generally I carve around most pot holes but I've hit a few and never had any serious damage. The big damage I got was accidentally pulling over some rebar sticking out the top of a parking stop. When I backed off of that it tore the entire left side of my bumper cover off. That was 'only" $400 in parts to fix.

[F30jamess]

I found this under the car I took off all the panels and it was the only wet spot I could see where a potential leak could occur from but then again it’s hard to tell because it wasn’t leaking the whole time I was watching the car when it was running.

[Hillbilly]

The residue pattern from your leak looks exactly like mine. Check the coolant reservoir for a little drip. My 330i was dumping about a gallon or more of coolant every 100 miles or so & the front of the engine bay on the driver's side had dried residue on everything. I couldn't find the leak for weeks. I finally filled the tank, started the car & watched for a leak for about 30 minutes. A tiny hole near the bottom of the coolant reservoir started pissing coolant as the heat/pressure built up. Has anyone replaced one f these coolant reservoirs?

[Hillbilly]

Did you get yours fixed? what was it?

[F30jamess]

It turned out to be the heat exchanger I ordered a csf heat exchanger and installed it in the snow. Funny story I didn’t officially get it installed until about 2 weeks ago, I snapped 2 bolts holding the hood latch closed so I was driving around with my hood not fully closed till I finally got them out. I had to buy a welding machine to get them out but now I have a machine incase I need it again.

[Hillbilly]

Glad you found the cause.

[bmfox]

My coolant light came on this morning, header tank low but not empty, topped it up is this normal to top your coolant up 👍

[F30jamess]

When’s the last time you checked the coolant level before the light came on? Maybe it’s normal to lose a small amount but just top it up and watch it check every morning to see if you can find anything

[bmfox]

Every other week I’m topping my 335i header tank up I’ve checked oil for any water in it but nothing so there a small leak somewhere any ideas how to find out other than a pressure test 👍