[juliomadara7]

Researched everything from our forums, YouTube and others testimonials for months now. I've jotted down notes and compiled a maintenance schedule for things that could go wrong or need to be replaced on our N55 cars.

To note also, of course these problems might not occur ever with YOUR N55 but I feel like a general reference is well needed.

Feel free to add on to this list


Potential Problems:
Belts, tensioner, pulley, radiator
Coolant reservoir
Coolant hoses
Boost leaks related to charge pipes
OFHG leak (Idler pulley/belts afterwards)
-With OFHG replacement notes of gasket material getting into ducts causing spun rod bearings
Valve cover gasket leak (PCV valve related)
Oil pan gasket leak
Front main seal leak
Water pumps & thermostat ($$$)
Vanos/boost solenoids
Electronic waste gate / valvetronic
Electronic steering rack
Fuel injectors ($$$)
HPFP/ LPFP ($$) (Older models mostly)
Diverter valve
Rod bearing failure (rare)
Walnut blasting (maintenance 60k+ mi)
Vacuum valve/leak (inlet pipe cracks?)
Intake inlet pipe
Running lean?
Hood latch


Maintenance Intervals: (In miles)
Black stone lab kit (for oil analysis)
Trans Oil: 50-60k
Sparks: 20-30k
Coils: As needed
Oil: 5-10k (your own preference)
Drive belt kit: 50k
Coolant: 15-20k
Brake Fluid: 10-15k
Diff fluid: 30k
Power steering fluid: 20-30k
Transfer case: 30-40k (X-Drive models)

[Rebound]

I think that, instead of walnut blasting, installing an oil catch can is less expensive/laborious, and should be more effective.

[indyjoeshmo]

Do you have a recommended oil catch can kit for the N55?

[johnung]

Originally Posted by juliomadara7

Researched everything from our forums, YouTube and others testimonials for months now. I've jotted down notes and compiled a maintenance schedule for things that could go wrong or need to be replaced on our N55 cars.

To note also, of course these problems might not occur ever with YOUR N55 but I feel like a general reference is well needed.

Feel free to add on to this list


Potential Problems:
Belts, tensioner, pulley, radiator
Coolant reservoir
Coolant hoses
Boost leaks related to charge pipes
OFHG leak (Idler pulley/belts afterwards)
-With OFHG replacement notes of gasket material getting into ducts causing spun rod bearings
Valve cover gasket leak (PCV valve related)
Oil pan gasket leak
Front main seal leak
Water pumps & thermostat ($$$)
Vanos/boost solenoids
Electronic waste gate / valvetronic
Electronic steering rack
Fuel injectors ($$$)
HPFP/ LPFP ($$) (Older models mostly)
Diverter valve
Rod bearing failure (rare)
Walnut blasting (maintenance 60k+ mi)
Vacuum valve/leak (inlet pipe cracks?)
Intake inlet pipe
Running lean?
Hood latch


Maintenance Intervals: (In miles)
Black stone lab kit (for oil analysis)
Trans Oil: 50-60k
Sparks: 20-30k
Coils: As needed
Oil: 5-10k (your own preference)
Drive belt kit: 50k
Coolant: 15-20k
Brake Fluid: 10-15k
Diff fluid: 30k
Power steering fluid: 20-30k
Transfer case: 30-40k (X-Drive models)

Thanks for taking a stab at this. Below are some comments:

Spark Plugs-
Stock engine- stock plugs & gap, 60k miles
Stage1 tune- stock plugs & gap, 30k miles
Stage2 tune (higher boost levels) NGK 97506 plugs gapped at 0.022". Change every 15k-18k miles.

Coils- 60k miles

Brake Fluid needs to be changed based on time, NOT mileage. You are changing because it picks up moisture over time which can destroy brake components inside the system. Every 2 years for safety.

XDrive also has a front differential. It has its own specific fluid that comes in a 0.5 liter bottle. Just get a bottle of BMW label fluid from FCP Euro. Every 30k miles wouldn't hurt.

Crankcase Vent Hose- it will appear fine on the outside but the heat and fumes destroy it from the inside. When removed, it will crinkle in your hands. I changed mine at 25k miles. See photos

[F32Fleet]

Originally Posted by juliomadara7

Researched everything from our forums, YouTube and others testimonials for months now. I've jotted down notes and compiled a maintenance schedule for things that could go wrong or need to be replaced on our N55 cars.

To note also, of course these problems might not occur ever with YOUR N55 but I feel like a general reference is well needed.

Feel free to add on to this list


Potential Problems:
Belts, tensioner, pulley, radiator
Coolant reservoir
Coolant hoses
Boost leaks related to charge pipes
OFHG leak (Idler pulley/belts afterwards)
-With OFHG replacement notes of gasket material getting into ducts causing spun rod bearings
Valve cover gasket leak (PCV valve related)
Oil pan gasket leak
Front main seal leak
Water pumps & thermostat ($$$)
Vanos/boost solenoids
Electronic waste gate / valvetronic
Electronic steering rack
Fuel injectors ($$$)
HPFP/ LPFP ($$) (Older models mostly)
Diverter valve
Rod bearing failure (rare)
Walnut blasting (maintenance 60k+ mi)
Vacuum valve/leak (inlet pipe cracks?)
Intake inlet pipe
Running lean?
Hood latch


Maintenance Intervals: (In miles)
Black stone lab kit (for oil analysis)
Trans Oil: 50-60k
Sparks: 20-30k
Coils: As needed
Oil: 5-10k (your own preference)
Drive belt kit: 50k
Coolant: 15-20k
Brake Fluid: 10-15k
Diff fluid: 30k
Power steering fluid: 20-30k
Transfer case: 30-40k (X-Drive models)

60k miles for plugs
100k miles for ignition coils

The gaskets for the valve cover and the OFHG just harden over time and leak. It's a BMW feature.

The PCV is integrated into the valve cover so just replace the cover when you do the gasket. However there's a hack repair for the PCV but YMMV.

Coolant really is lifetime. Just replace it and some hoses whenever you change out the thermostat/water pump.

There's no power steering fluid to change.

Injectors, HPFP/LPFP are stout. Just don't tune the shit out of the car.

[Polo08816]

Originally Posted by F32Fleet

60k miles for plugs
100k miles for ignition coils

The gaskets for the valve cover and the OFHG just harden over time and leak. It's a BMW feature.

The PCV is integrated into the valve cover so just replace the cover when you do the gasket. However there's a hack repair for the PCV but YMMV.

Coolant really is lifetime. Just replace it and some hoses whenever you change out the thermostat/water pump.

There's no power steering fluid to change.

Injectors, HPFP/LPFP are stout. Just don't tune the shit out of the car.

My injector in cylinder #6 was stuck open around 110k miles. Car had to be towed how. Stock powertrain.

I would replace the injectors and HPFP at 100k miles for preventative maintenance.

[Insane435]

Does anyone think its worth replacing the actual valve cover as well when you do the gasket?

[F32Fleet]

Originally Posted by Insane435

Does anyone think its worth replacing the actual valve cover as well when you do the gasket?

Yes only because the labor is intensive. You'd hate to spend $600 in labor twice within 15k-20k miles.

[thejeremyman9]

Is there a fuel filter on these cars? I don't think i have ever seen that mentioned anywhere, in the context of maintenace or elsewhere.

[Polo08816]

Originally Posted by thejeremyman9

Is there a fuel filter on these cars? I don't think i have ever seen that mentioned anywhere, in the context of maintenace or elsewhere.

My understanding is that it's in the fuel pump.

[thejeremyman9]

Originally Posted by Polo08816

My understanding is that it's in the fuel pump.

Which one? I have heard mentioning of a screen in/before the HPFP.

[F32Fleet]

Originally Posted by thejeremyman9

Is there a fuel filter on these cars? I don't think i have ever seen that mentioned anywhere, in the context of maintenace or elsewhere.

Yes, in the gas tank. It's part of the LP fuel pump and doesn't require preventative replacement.

[cfm56d7b]

juliomadara7, nice summary and well done. Connecting rod bearing wear is a rare problem and can be diagnosed by performing oil analysis (metal shavings will be present).

[_bdiddyb_]

Originally Posted by indyjoeshmo

Do you have a recommended oil catch can kit for the N55?

I installed this one on my 335i:

https://www.ecstuning.com/b-ecs-part...03779ecs05akt/

[juliomadara7]

Originally Posted by Rebound

I think that, instead of walnut blasting, installing an oil catch can is less expensive/laborious, and should be more effective.

I've heard the same and have seen a couple of examples. Seems like the best use out of it is those running tunes etc, although I hear the figment isn't precise. Definitely a good add on for preventative maintenance

[juliomadara7]

Originally Posted by indyjoeshmo

Do you have a recommended oil catch can kit for the N55?

The only reputable one I've seen is by BMS

[juliomadara7]

Originally Posted by cfm56d7b

juliomadara7, nice summary and well done. Connecting rod bearing wear is a rare problem and can be diagnosed by performing oil analysis (metal shavings will be present).

Seems like it's mostly in the E90 forums but still with the N55. It's a weird case man, BMW recommends you prime the system for anything interrupting the engine oil supply. If that's the case though then it should be done with every simple oil change.

Idk most culprits is particles getting in the house, air bubbles, starvation of oil for a second. Hopefully we can get some solid reasoning for it :

[Joe_435i]

Are these recommendations for a stock or tuned N55?

[thejeremyman9]

Originally Posted by Joe_435i

Are these recommendations for a stock or tuned N55?

Both. The only thing tuning really does is shorten the interval for things like oil changes, plugs, etc. Other maintenace items like gaskets wont be affected by a tune.

[Insane435]

Originally Posted by F32Fleet

Yes only because the labor is intensive. You'd hate to spend $600 in labor twice within 15k-20k miles.

just did the valve cover and gasket. Not a terrible job, but it did take me 9 hours in total. I had to replace the PCV hose since it broke. That probably took me an extra hour. I also dropped a tool and fought hard to loosen and tighten one of the bolts. If i could have eliminated the nonsense, id say its a 6 hour job.

[F32Fleet]

Originally Posted by Insane435

just did the valve cover and gasket. Not a terrible job, but it did take me 9 hours in total. I had to replace the PCV hose since it broke. That probably took me an extra hour. I also dropped a tool and fought hard to loosen and tighten one of the bolts. If i could have eliminated the nonsense, id say its a 6 hour job.

I'm jealous, I wasn't so lucky to be able to perform the work myself.