[a_wolly]

Hi, been following these forums since I purchased my 2011 523i F11 (73k miles) a few months back. I believe this is the N53B30A engine.

In the first couple of weeks of ownership I noticed an oil leak due to cracked valve cover, so that's already been replaced. The car also has issues with AC leak, coolant leak and rough idle on cold start but I'll save those for another thread after my indie takes a look this week. Now trying some DIY servicing for the first time to save further expenses. Two questions I need help with...

1. Despite taking a look around various forums and YouTube vids I'm unable to find a guide for replacing the air filter. Despite looking super easy, there's an engine strut/brace across the top of the filter cover that first needs removing (see pic, which seems to have uploaded upside down). I want to know if anyone can tell me what the torque spec is for the bolts holding this in place? Also, if the bolts need renewing does anyone know the part number (or the catalogue name of the strut so I can source one)?

2. Despite calling BMW and asking my local indie, neither are forthcoming with telling me the air gap spec for the spark plugs. I'm replacing with NGK ZKBR7A-HTU plugs as recommended on Bimmerprofs but it's not clear if these are pre-gapped; the diagram on the plugs suggests not. (I know these plug go into the chamber at an angle so have the Laser 14mm plug socket for that and will tighten to 20nm.) Whilst I'm at it I'll replace coils too since there's no evidence they've been done in the past.

Any advise much appreciated, thanks!

[a_wolly]

Seems this isn't as common as I'd imagined given the silence. Hopefully I'll be fine just using the plugs straight out of the box with default gap and hand-tightening the re-used strut bolts.

This is all I could find on the gap but it's for the N52 motor: https://www.zpost.com/forums/showthread.php?t=733657

... Gave me some hope they're fine to use out of the box, since there's reference to the multi-electrode plugs being pre-gapped.

[M_Bimmer]

Originally Posted by a_wolly

Hi, been following these forums since I purchased my 2011 523i F11 (73k miles) a few months back. I believe this is the N53B30A engine.

1. Despite taking a look around various forums and YouTube vids I'm unable to find a guide for replacing the air filter. Despite looking super easy, there's an engine strut/brace across the top of the filter cover that first needs removing (see pic, which seems to have uploaded upside down). I want to know if anyone can tell me what the torque spec is for the bolts holding this in place? Also, if the bolts need renewing does anyone know the part number (or the catalogue name of the strut so I can source one)?

Hope this helps.....

[M_Bimmer]

Originally Posted by a_wolly

2. Despite calling BMW and asking my local indie, neither are forthcoming with telling me the air gap spec for the spark plugs. I'm replacing with NGK ZKBR7A-HTU plugs as recommended on Bimmerprofs but it's not clear if these are pre-gapped; the diagram on the plugs suggests not. (I know these plug go into the chamber at an angle so have the Laser 14mm plug socket for that and will tighten to 20nm.) Whilst I'm at it I'll replace coils too since there's no evidence they've been done in the past.

"Unlike most engines, the spark plugs’ position in the N43 and N53 is angled in the spark plug tunnel by more than five degrees. A look into the spark plug shaft does not reveal this special design [any anyone] unaware of this particular construction, [so anyone using] a standard solid bi-hex (12 point) socket, instead of the necessary bi-hex socket with an integral articulated joint"...may end up fracturing the ceramic insulator on the new spark plug, resulting in "failed" plug.

• Spark plug, High Power, NGK Part Number: ZKBR7A-HTU, BMW Part Number: 12120038349 (Gap set by Manufacturer)

[a_wolly]

@M_Bimmer Thank you, just what I was after!

[ChiltiCoatl89]

Awesome! I plan to do my Tune up soon! I have this Special Tool handy!

[Unspec]

For the torque specs:

Front: 56nm, does NOT need to be renewed. If you want to, P/N is 07119905147

Rear: 30nm + 90 degrees, DOES need to be renewed. P/N is 07147029829

[a_wolly]

Hi all. Just thought I'd follow-up on my post with some more context and pics of the coils and spark plugs.

One of the motivations for replacing these was due to intermittent rough running and 'fluttering' accelerator pedal (occasionally noticeable when holding at ~2k RPM) over the last 3-4 months since a valve cover replacement causing an oil leak.

I had an indie read the codes which showed a few 'rough run in stratified charge' codes in cylinders 1&2 over last three months; no EML or misfires. They said the injectors aren't leaking but having used a borescope, claimed pistons in cylinders 4&6 showed polished spots suggesting irregular injector spray patterns. I've been stressing about potentially needing to replace all six injectors (£3k) and damage to the engine during my indecision.

Anyway, since all injectors were only replaced with new OEM index 11 units 15k miles ago I was sceptical they were borked, unless clogged or an issue upstream (e.g. HPFP). Therefore, I figured changing coils and plugs was worth a shot.

This is what they looked like, which to my layperson eyes seems relatively bad (specifically the coils) and is presumably the impact of the oil leak/neglect by previous owners/mechanics (- I was surprised they weren't caught when the valve cover was replaced). Car appeared to run silky smooth after replacing these, so fingers crossed the symptoms won't return, otherwise my injectors are most likely at fault. Will report back.

Incidentally, anyone tried running engine flush products through the Piezo injectors? BimmerProfs advises against it due to the risk of clogging them with sediment from the tank but one indie I spoke to suggested running a few bottles of something called Pro-tec (I think) through.

Unspec Your cross brace specs seem different to those in the diagrams above; I.e. they don't seem to have the rear bolt spec, though I think the diagram is for an N54 vehicle. Since I need to remove the front bolt and loosen the rear to move the bar, guess I'll be needing to renew the rear one in any case. Thanks!

[Unspec]

Originally Posted by a_wolly

Hi all. Just thought I'd follow-up on my post with some more context and pics of the coils and spark plugs.

One of the motivations for replacing these was due to intermittent rough running and 'fluttering' accelerator pedal (occasionally noticeable when holding at ~2k RPM) over the last 3-4 months since a valve cover replacement causing an oil leak.

I had an indie read the codes which showed a few 'rough run in stratified charge' codes in cylinders 1&2 over last three months; no EML or misfires. They said the injectors aren't leaking but having used a borescope, claimed pistons in cylinders 4&6 showed polished spots suggesting irregular injector spray patterns. I've been stressing about potentially needing to replace all six injectors (£3k) and damage to the engine during my indecision.

Anyway, since all injectors were only replaced with new OEM index 11 units 15k miles ago I was sceptical they were borked, unless clogged or an issue upstream (e.g. HPFP). Therefore, I figured changing coils and plugs was worth a shot.

This is what they looked like, which to my layperson eyes seems relatively bad (specifically the coils) and is presumably the impact of the oil leak/neglect by previous owners/mechanics (- I was surprised they weren't caught when the valve cover was replaced). Car appeared to run silky smooth after replacing these, so fingers crossed the symptoms won't return, otherwise my injectors are most likely at fault. Will report back.

Incidentally, anyone tried running engine flush products through the Piezo injectors? BimmerProfs advises against it due to the risk of clogging them with sediment from the tank but one indie I spoke to suggested running a few bottles of something called Pro-tec (I think) through.

Unspec Your cross brace specs seem different to those in the diagrams above; I.e. they don't seem to have the rear bolt spec, though I think the diagram is for an N54 vehicle. Since I need to remove the front bolt and loosen the rear to move the bar, guess I'll be needing to renew the rear one in any case. Thanks!

Not sure why M_Bimmer's diagram contains discrepencies, as you can see that the torque spec refers to a 1AZ and 2AZ, yet 2AZ is missing from his diagram. This is the correct diagram I believe: