BMW 3 Series Overheating With No Heat: Fix Guide

Hey there! I had very similar issues with my 2010 BMW 5 Series diesel last winter. Initially thought it was just the thermostat, but turned out the water pump had failed, which then caused the bypass valve to stick. The symptoms were identical, engine running hot and no heat in the cabin. Had it fixed at a garage and discovered the water pump failure had actually caused some damage to the cooling system. The mechanic found metal debris from the pump had gotten into the system, which is why the bypass valve got stuck. They had to flush the entire cooling system, replace the water pump, and install a new bypass valve. It was quite a serious issue that needed immediate attention to prevent engine damage. The repair wasn't something I could put off, as continuing to drive with these symptoms risks overheating the engine. Based on your symptoms, I'd strongly suggest getting it checked soon, it might not be exactly the same issue, but those warning signs shouldn't be ignored. Best of luck!

Thanks for sharing your experience, really helpful! Just wondering, do you remember roughly how much you ended up paying for all those repairs? Also, has everything been running smoothly since then, or have you had any other cooling system problems pop up? My mechanic mentioned something about the cooling system needing regular maintenance after such repairs, so I'm curious about the long-term outcome of yours.

Hey again! Happy to tell you how it turned out! After getting everything fixed, my car's been running like a dream. The mechanic actually discovered that the bypass valve malfunction was a warranty case since it was a consequential error from another issue. So fortunately, I didn't have to pay anything for that specific repair! The best part is that I haven't had a single cooling-related problem since then, it's been working perfectly. The cabin heating works great now, and the engine temperature stays exactly where it should be. About the regular maintenance your mechanic mentioned, I've just been following the standard service schedule, and that's been more than enough. Haven't needed any extra cooling system work beyond the normal checks during regular servicing. Honestly, getting it fixed properly the first time made all the difference. Just make sure you get it looked at soon, these things can get worse if you wait too long! Let me know if you need any other info!

Thanks so much for all that info! I actually bit the bullet and took it to a new mechanic yesterday. You were spot on, turned out my water pump was failing too! Got it all sorted now. The mechanic was actually really great, explained everything clearly, and even showed me the worn-out parts. Total bill came to about eight hundred for the pump, valve, and system flush, but honestly, it was worth every penny. The car's running perfectly now, no more temperature issues, and the heating's working brilliantly again. The difference is like night and day! Really glad I didn't put it off any longer. The mechanic said I caught it just in time before it could cause any serious engine damage. Think I've finally found a reliable mechanic too, which is a huge relief after my last experience. Thanks again for sharing your story, it really helped me make the decision to get it checked out properly!