[Chemdad]

Greetings, This may or may not be my first forum post but I'm always casually browsing.

I'm having a lot of trouble with my 2006 325i with the n52 engine and hoping someone could help me out. I'm getting very demotivated and think it might be time to get a new car. I'm going to set this up in a timeline and address issues I know about the car. Thank you in-advance!

Purchased the car:

4 months after: car throws misfire codes I replace all spark plugs and all coils.

1 year after: car throws misfire codes for 2 cylinders I replaced both coils and problem went away. !!!IMPORTANT!!! When replacing the coils I noticed the valve cover bolt in the very front left of the motor was spinning. I pulled the bolt out with my fingers and saw it was snapped into the head. I also developed a slight oil leak that was cause the oil to drip onto the cat.

1 year 4 months ( 1.8 years total) Drive belt falls off (bad pulley) Replaced all pulleys and belts.

A week after that: Coolant explodes all over engine bay, replaced reservoir cap problem solved.

Two days later: lost all coolant again, inspected engine saw the plastic radiator housing was rotted so I ordered a new aluminum one coolant issue is fixed. (Tested water pump and has great flow so hoping that never goes!)

About a week or so later (current day) Started car and it was fine. Got to my destination and it misfires. Drove the car back home (10-15mi) low rpm and it ran great like nothing was misfiring except at a stop or low speed.

Still had an extra coil so when I got home I took out the coil and noticed it was drenched in what I think was burnt oil? took out the spark plug and it was very dark, the tip and everything was a dark dark brown and black whilst also being covered in oil. My socket was covered in oil and there was a little puddle of oil where the spark plug sits.

I also took a picture inside down through the spark plug hole and it looks like a dark gravel driveway or street texture. I'm assuming that's the carbon build up on the cylinder head? I could be completely wrong just wanted to note that.

I replace the coil and start the car but the coil popped right off like a cork gun. Put it back in seated it nice and the same thing happened again. I switched the spark plugs and coils from cylinder 3 which was fine and put them into cylinder 4 which was the busted one. Cylinder 4 fires fine but the 3rd one popped the coil off like the 4th.

I love the car and would hate to get rid of it, this all stemmed from what I believe was the dealership. Car was single owner, excellent service history, dealership installed the valve cover gasket and a few others. But they neglected to tell me that the bolt was snapped. Car was bought for a pretty good deal with no warranty kinda just "as is" so I'm responsible to get these things fixed.

Here's my options and I'm by no means a mechanic. I did all the work except for the pulley and belt.

I need to replace valve cover gasket and have bolt removed and re-tapped.
I'll need to buy all new spark plugs and coils.

I'm very confused to why the coil kept popping out? I read that you could possibly strip the plug threads and gasses will expand and blow the plug out but why did it only blow out the plug.. actually now I just thought about it. The bad sparkplug was probably worn and will cause the gasses to pop out in any cylinder. It has to be that.

Regardless if you made it this far I greatly appreciate you!!! Despite being an essential employee I was greatly impacted by the covid pandemic and having all these issues while receiving less pay and hours and the struggle of just buying a house I'm about to drive this car off a cliff. I really do enjoy my car though and I always keep up with whatever minor maintenance and oil changes I need to do. My blinker light always stops working after I replace the fitting and the light too F$#%#!!

Sorry but no TL;DR I'm a mess even typing this and I apologize. I live in the Lehigh Valley area of PA, If you're local and work on these cars feel free to send me a message. I do have a mechanic who will do the work but I'd love to work with the masterminds that frequent this forum. Thank you guys!!

[E92William]

That coil popping issue is quite weird. The 06 325i has the magnesium cover which in my own old 325 developed cracks all around the spark plug holes and a vacuum leak by the spark plug hole itself. I replaced it and didn't solve the issue anyway I got rid of it for a profit. I suggest doing a smoke test because that's quite weird that it's popping it like that. Mine the smoke that was being put into the intake was coming out of the spark plug holes but I didn't have the coil popping out issue. it almost seems as if there is indeed some cylinder pressurized gas flowing past the plug into the coil and pushing it. Also my spark plug hole was full of oil too like a whole pool.

This is reason 92736849273 why I don't let the dealer touch my car they don't really care about it. The bolts in the magnesium cover cars are meant to be replaced all at valve cover gasket replacement which I'm sure as hell they didn't which caused that one in front to snap. You shouldn't need to rethread it just try remove it. Most of the torque of the bolt itself is on the head.

[Chemdad]

Originally Posted by E92William

That coil popping issue is quite weird. The 06 325i has the magnesium cover which in my own old 325 developed cracks all around the spark plug holes and a vacuum leak by the spark plug hole itself. I replaced it and didn't solve the issue anyway I got rid of it for a profit. I suggest doing a smoke test because that's quite weird that it's popping it like that. Mine the smoke that was being put into the intake was coming out of the spark plug holes but I didn't have the coil popping out issue. it almost seems as if there is indeed some cylinder pressurized gas flowing past the plug into the coil and pushing it. Also my spark plug hole was full of oil too like a whole pool.

This is reason 92736849273 why I don't let the dealer touch my car they don't really care about it. The bolts in the magnesium cover cars are meant to be replaced all at valve cover gasket replacement which I'm sure as hell they didn't which caused that one in front to snap. You shouldn't need to rethread it just try remove it. Most of the torque of the bolt itself is on the head.

Thank you so much for your response!!

The coil would only pop on whichever cylinder had the bad spark plug from the initial misfire which was #4 I was thinking maybe the spark plug itself was stripped or lost its seal.

That sounds like the case about the dealership, all of the bolts look rather spent. They have blue paint on the tops of them if that means anything.

The indy who did my drive belt and pulley said I was looking at around $400 to get that bolt out, I was thinking of trying to do a package deal and have him replace a few gaskets and the valve cover gasket. I'd also replace the spark plugs and coils as well but that is something I'm able to do on my own. Hopefully the indy will work with me on pricing since all parts are in the same area.

[E92William]

Well blue paint means new oem bmw bolts so who knows maybe they actually did replace them.

So have you replaced this plug and did it keep popping the coil out? Or is it not doing it again?

If you can strike a deal with the indy for all the work you should be okay. Specially for them to diagnose the issue and what's actually causing misfires and such. Hopefully that cover isn't cracked or warped because it isn't exactly cheap to get a new one.

Try attaching some pictures here, specially that bolt.

These cars as they age will have these issues specially hoses and plastics, I mean that 325 is what 14 years old now? Just the name of the game, I'd rather replace parts than have a monthly payment.

[Chemdad]

No, I did not have any new plugs to try that theory. The one specific plug (cylinder 4) would cause any of the non faulty coils to "pop".

I'm going to run to the store tomorrow and pick up a new plug to see if it's the actual plug. If its the plug I'll pop the coil back in and drive the car back to my house until I'm able to get that gasket replaced.

I'm hoping nothing crazy is wrong with the cover, I'm assuming you're talking about the valve cover that's about $300 from fcp euro. If that's the part you're talking about I might pick that up since it's not too expensive.

I'll try and post some photos tomorrow and videos. The bolt is just your average snapped bolt lol, its broken into the head not so much the valve cover.

Yeah I kinda knew that's what I was getting into but when I saw the service history it looked pretty promising and when the dealer gave me their service history I saw there was about 7 gaskets replaced with one being the orange valve cover gasket.

I actually owe around around $800 to pay it off and with the thought of having no monthly payment I think I might just invest a few K back into the car. I bought it with 80k miles 2 years in November. It now has 118k.

Tomorrow I will try and upload pictures of all fault points and see if a 2nd set of eyes might be able to dissect this further. Thanks again for the replies and such!!


EDIT: I'm also thinking to replace the fuel injectors as well. I've read that they can cause fuel to drip onto the spark plugs causing failure.

[Chemdad]

UPDATE! The culprit was the stripped spark plug. Ended up buying a pair of plugs and coils from my local parts store. Put only the new plug and coil into the bad cylinder and it started right up. No more popping coils out. I'm going to contact my indy tomorrow and try and work out a package deal on my work.

Thinking about having the valve cover and gasket replaced, clean or replace fuel injectors and fuel pump, all new coolant hoses and maybe water pump? (its flowing nice not sure if it was replaced not on service history) and maybe some miscellaneous gaskets that are prone to fail. If you guys think I missed anything please let me know.

[E92William]

That's great! That spark plug issue I hadn't seen before but glad it wasn't too bad. If the engine is running good and not leaking I think you're fine if the gaskets were replaced at the dealer.

If you're not talking about the valve cover bolt and instead you mean one by the back of the oil filter housing then it might be a head bolt which likes to break sometimes on these engines but it can just be pulled out and replaced, though I doubt it's that.

Good to have a new pump at hand at least in case it does fail.