[spielnicht]

Still feeling a little sour about how much I had to pay the dealer to replace my coils and plugs when I took it in for the high-pressure fuel pump issue that crippled the car, I know want to get ahead of issues that might pop with the car at its current age and mileage (65K). Zero plans to sell the car for at least another 4 years.

Rear Diff Bushings
Dealer pointed out the rear diff big bushing is cracked. I verified it to be true - so my first project is to replace it and the 2 other rear diff bushings even though they appear fine for now - might as well considering how involved the process is. Dealer wanted $1k, I can do it for $125 with genuine BMW bushings and new bolts. Will cost me another $120 for the tool - but that's an investment - so I'm good with that.

Anything else that would need replacement that anyone can think while exhaust completely removed and rear diff lowered?


Coolant Flush
TIS recommends coolant change every 4 years - I don't remember ever doing this for the car. I might as well replace as many of the fail-prone hoses while at it.

Do you know what hoses should be replaced at this point, or in anticipation of them going bad in the near future?


Tranny/Rear Diff Fluid
I keep reading mixed messages about this.

Should they be replaced or stick with BMW's recommendation that they're good for life?

Dealer also mentioned that I have an oil leak developing around the engine - something around $3K of a job but they said it's not an issue yet and can wait. I don't remember where they said it was happening, but I'll deal with it next year on my own. There is also a clunking sound coming from the front axle - sounds like the passenger side brake pad sliding back and forth when in reverse then going fwd. I have to figure out what's causing that.

Anything else you guys can think of in terms of maintenance or wear/tear that I should take care of would be great.

[SWFLf10]

While you've got the exhaust off and are working on the differential, I'd check out the rubber guibo on the driveshaft for any cracks that may be starting to develop, and replace if needed. Also see how much play there is in the center bearing on the shaft while you're there, and replace if necessary.

I don't know if your engine has something similar, but I know when I did a coolant swap with my water pump and thermostat replacement, I also replaced the "Mickey mouse" flange coolant hose that is know to become brittle and fail on the N55.

I recommend the transmission and differential fluid swap. I did these myself and it wasn't too much hassle, and I noticed smoother shifting afterwards (I am at 110k miles, did it at 105k). It was fairly simply to do if you have a small transfer pump for the differential and a fluid extractor/filler for the transmission and ISTA to run you through the process step by step.

My brakes have the well know "clunk" when going from forward to reverse ever since I changed pads to an aftermarket brand. This is usually because the aftermarket pads are made slightly smaller than OEM, so they don't fit as snugly, allowing them to shift slightly in the brake assembly when changing direction and apply the brakes.


As for parts, I highly recommend FCP Euro, as they have good pricing, great customer service, and a lifetime warranty on everything they sell.

I used a small mity-vac fluid extractor with a flexible hose for my differential fluid, and a Schwaben 6 L fluid extractor/filler for the transmission.

[Surly73]

My 2 cents:

Rear Diff the rear bushing cracking is common, the front two is not. I believe every account I've read says that the fronts have not failed on anyone but the rear fails (and fails again) with regularity.

I need to replace mine, and I'm considering Powerflex urethane for that bushing when I do it. You require a special tool kit to remove/replace the bushing which is fairly easy for onshore Americans to get - less easy in other places.

The legit procedure is to drop the entire exhaust. I have seen videos of people do it without doing that. My flex disc is also cracking. I'm not sure if you can also do the flex disc with no exhaust drop.


Coolant Flush it's a pain but yes it should be done before electrolysis begins and starts to attack the block from the inside out. There is a special fill procedure using a vacuum apparatus that uses shop air. ECS sells one (https://www.ecstuning.com/b-schwaben...l/003466sch01/ You can use it afterwards on any brand of vehicle from what I can see in order to reduce/eliminate bleeding.

I can't link you to the newtis procedure any more. I was never able to discover a proper procedure that didn't use the special tool. Here and there online I've seen conspiracy theorists mention that the special tool is all just a scam, but I don't see as many vents and bleed points in this system compared to others. I just bought the tool once when it was on sale.


Diff and Transmission yes, absolutely, no brainer. ZF recommends a fluid and pan change no less often than every 60k miles / 100k km.

The transmission is a bit of a pain in the butt, but with my 535i X with and air/fluid cooler I had lots of time to get it done on stands. FCP Euro has a kit that makes using genuine fluids and filter a no brainer (https://www.fcpeuro.com/products/bmw...-24118612901kt

Near my manufacture date at least there is a lot of confusing and conflicting information about diff fluids. From what I could see on my car, the rear diff for mine came with SAF-XO, which is basically any quality 75W90 GL5 oil. The front diffs (if equipped) came with a variety of fluids which no one seems to have a directly replacement for (but some folks on the internet just put the same 75W90 GL5 in there with "no problems"). I ended up putting genuine Hypoid Axle Oil G2 in mine.


Figure out if your leak is the OFHG. Your belts need to stay clean and dry. On the N55 a failed belt usually gets rammed through the front main seal behind the crank pulley and into the valve gear. You have a real problem then.

If you do the OFHG job, make sure to do the oil pump priming procedure. You'll find lots of stuff online saying it isn't necessary - it is. Many N55 owners are finding out the hard way with spun rod bearings after doing the job. This is a "new" development over the last 18 months or so.


Things will be more difficult to find full procedures and torques with newtis gone, but you may need to do some looking around. I like to view youtube videos of people doing more complicated jobs I'm looking to do since you find useful tips about heat shields to remove or a certain kind of wrench to get that you don't necessarily find in the factory procedure. Unfortunately I also find conspiracy theorists not replacing single use torque-to-yield fasteners and stuff like that too because "you don't need to" and they had "no problems". Unfortunately the F10 is full of single use fasteners.

[spielnicht]

Thank you both for the detailed info - this is awesome. I'm gonna start with the rear diff bushings and will change the fluid and that of the transmission while at it. Good call on the guibo - forgot those go bad. Love FCP Euro and will def get most of what I can't get from the dealer. My local BMW dealership has been surprising me with their prices lately - many times beating out FCP Euro and ECS - but that's if/when I got with genuine BMW parts, obviously.

I'll need to do some upfront reading and learning about the coolant flush - so I'll tackle that in winter break.

[Trainwreck914]

You never specified which year and model you have. But 65k is pretty low. Assuming it's the n55. And the dealer quote of $3k. I'm going to assume it's the oil pan gasket. It's an extensive job. And requires quite a bit of time and skill. You'll have to suspend the engine from above and remove the subframe to remove the oil pan. All to replace a $20-30 gasket! If early model 11-13 I'd replace the water pump and thermostat along with coolant. My hoses looked pretty stout when I did mine. So I did not replace any. Not sure which one is the Mickey Mouse one lol. And the bleed procedure is easy. Being that the pump is electric. You can look it up. All else seems covered by the other 2 responses. If you plan on tackling these jobs yourself they can be difficult and tedious. But if you take your time nothing is impossible. I've done all except the rear diff bushing. But it's next on my list.

[beegeezy]

Originally Posted by Trainwreck914

You never specified which year and model you have.

This is one negative of only browsing and commenting on the mobile site. It shows the vehicle info under the username and signature on the desktop version. The OP has a 550, so all the N55 advice is moot.

[spielnicht]

Sorry, assumed the sig would be a giveaway - my bad. It's a 2014 550i.

Yeah I zoned out when the service rep went through the additional issues. All I recall about the oil leak was that it was in early stages and not an issue because it was "leaking on the outside". I didn't quite understand that statement but didn't care at the time because I was just concerned with getting the car running again. I suppose it's probably similar to the N55 oil pan gasket and sounds like out of my league - so I'll need to find an indy shop to do it.

Originally Posted by Trainwreck914

You never specified which year and model you have. But 65k is pretty low. Assuming it's the n55. And the dealer quote of $3k. I'm going to assume it's the oil pan gasket. It's an extensive job. And requires quite a bit of time and skill. You'll have to suspend the engine from above and remove the subframe to remove the oil pan. All to replace a $20-30 gasket! If early model 11-13 I'd replace the water pump and thermostat along with coolant. My hoses looked pretty stout when I did mine. So I did not replace any. Not sure which one is the Mickey Mouse one lol. And the bleed procedure is easy. Being that the pump is electric. You can look it up. All else seems covered by the other 2 responses. If you plan on tackling these jobs yourself they can be difficult and tedious. But if you take your time nothing is impossible. I've done all except the rear diff bushing. But it's next on my list.

[ezaircon4jc]

Originally Posted by spielnicht

... All I recall about the oil leak was that it was in early stages and not an issue because it was "leaking on the outside"...

That is definitely NOT a head gasket leak. A true head gasket is a right-now fix before the coolant contaminated oil destroys the engine!

[Trainwreck914]

Originally Posted by beegeezy

This is one negative of only browsing and commenting on the mobile site. It shows the vehicle info under the username and signature on the desktop version. The OP has a 550, so all the N55 advice is moot.

Yeah. Hard to tell using mobile app.

[spielnicht]

I gotta take it in to the dealer again for that ammonia-like smell that I'm noticing and thinking cats related, so I'll ask the service rep to "remind me" of what needs to be fixed and then I'll know where the oil leak is.

Originally Posted by ezaircon4jc

That is definitely NOT a head gasket leak. A true head gasket is a right-now fix before the coolant contaminated oil destroys the engine!

[spielnicht]

QQ. Was about to order Powerflex bushings for the rear diff when I noticed they also have them for the front control arms. I might as well get them all together. Before I do though, anyone know where I can find the tool to press them out/in of the control arms? I searched everywhere and got zero hits for the F series. Subframe tool I already bought, just can't find one for upper or lower arms. Thx.