[Tejsingh]

Hi all,

My first post here, apologies if this has already been covered in another post but I have tried searching and not quite found the same as my issue. Apologies in advance for the long post!

I have a 2006 325i E92. Few weeks back I noticed a big idle issue when starting the car, really rough and certainly didn't sound well. Took it to a garage on the short trip home and they checked the codes - P0304 - cylinder 4 misfire. The garage told me it could be anything and could be a costly repair. So I thought I'd try a few things myself.

I'm not a mechanic or even too familiar with engines but I did some searching in the forums and tried the following in the order below:

1. Replaced all spark plugs
2. Replaced cylinder 4 coil
3. Replaced fuel injector on 4th cylinder

After each of the steps nothing seemed to improve and code was the same (I checked with my cheap reader). I then had a family mechanic run a quick compression test on the 4th cylinder and it was sitting on dead zero. Other cylinders looked fine besides the dead 4th cylinder. He said he'd have to take the valve cover off and it could be any number of things - could be £800-£900 or well over £1000 to repair in labour and parts. Especially if the head needs to be taken off.

Again - I thought I'd try a few things myself and see how far I get. Please keep in mind I'm not a mechanic or overly familiar with BMW engines so I've spent quite a few hours reading forums and guides and watching youtube videos!

The car hasn't been driven since the issue, luckily I have another car I can drive for work etc. So I started about a week ago in taking the valve cover off. I managed to do this with great difficulty but got there in the end. Lots of oil everywhere, I'll be giving the whole engine a good clean once I get it sorted!

Inspecting the engine the only issue I could see was that on the 4th cylinder the intermediate (rocker) lever was loose sitting at the bottom of the head and the spring arm was resting on ones of the gaps on the cam. My drive home and the odd starting of the engine to test after plugs/coil/injector has caused a fair amount of grinding! I'm hoping this hasn't caused any issues to the cam.

I wanted to inspect the area around the intermediate rocker further, the other rocker and the spring etc. So I went ahead and removed the spring, slowly, and inspected everything as closely as I could. Nothing seemed to be a amiss, cracked or chipped or damaged in any way. I checked the "roller cam follower" that the intermediate lever sits on as well as pulling out the intake "HVA" as far as it could and it all seemed fine. The spring above the intake valve looks fine but I'm wondering if there's anything wrong with the valve - could it be slightly bent or stuck?

So I'm not sure what would have caused the rocker to come loose and the spring become unattached. My fear now, in putting the rocker back in and getting the spring back in place (I haven't got the special tool so it's going to be a pain!) is that I get it all back together and it comes loose again when I try to start the car.

Does anyone have any thoughts as to why the spring may have come out and the rocker come loose?

Will try to upload some photos of my adventures and thank you in advance!