[Y.dae]

Hello everyone,

I have an e93 bmw 325i with an n53 engine which has been a headache for me the past 6 months!

It all started off at the beginning when the water pump gave up on me while I was out and I had no choice but to drive it back home. On that drive home the engine did overheat a little (reaching about 150-160C). £1700 later I had the water pump, thermostat and oil cooler replaced. However, the people who had topped up my coolant at the garage must have over filled the coolant reservoir (I am assuming) because the reservoir literally exploded and spilled all the coolant out while I was driving. This caused the engine to overheat a SECOND time (also around 150C) as I drove home.

After this, the next time I went to start up the car in the morning, there was a misfire on cylinder 2. This is where the real issue began. The misfire used to only happen on cold starts and then disappeared after about 5 minutes of driving. Firstly, I decided to replace all spark plugs, which fixed the issue for a couple of days (no idea how) and I thought I was done. BUT the misfire on cylinder 2 came back. I then decided to swap around the coils which did nothing as the misfire was still remaining on cylinder 2. Finally, I decided to replace the injector on cylinder 2 with a used index 11 from eBay. This didn’t fix the issue. Then I did some reading, I heard that I had to replace either the whole bank or all 6 of the injectors. Me being cheap, I decided to buy 3 used index 11s from eBay again which, no surprise, did nothing and the misfire still remained on cylinder 2. I also tried swapping injectors 1,2,3 with 4,5,6 (the eBay injectors worked fine in 4,5,6) and the misfire was still on cylinder 2. After that, I took it to a friend who knew a friend who worked on ecus (I don’t know how good they are) and he assured me that there was nothing wrong with my Ecu after doing some testing.

Now I am stuck. I don’t think it’s injectors (as I swapped banks and the issue still remained) nor do I think it’s the Ecu (as it has been “tested”).

The issue has got worse after just driving on it while ignoring the cold start misfire (as I had given up), because now the cold start misfire doesn’t disappear and now the misfire is constant on cylinder 2 without disappearing despite driving for long periods of time. (I know this may hurt a lot of people)

Have I caused irreversible damage or does anyone have any idea what is going on with this misfire?

Thanks!

[lookalikehuuh]

Its likely the overheating events caused a failure of something (heads, head gasket, or block) so you are likely loosing compression on that cylinder. You might be able to do a compression test or a block test (with that blue liquid) to give you an idea if this is what you are facing.

Also your reservoir didn't fail because they overfilled it, the system will automatically bleed out coolant if its overfilled, more likely it failed because #1 its plastic, #2 it was probably original from 2009, #3 heat cycles galore, #4 an overheat event.

Also, there is always a choice of NOT driving the car when it begins to overheat. Everyone says they "had no choice" but thats never true especially nowadays with Taxi, Uber, Lyft, Tow truck etc. Long Story short, spend $300 on a tow truck and save a $4k-$8K in repairs for a blown up engine.