Find out when the water pump was changed if you can thru bmw carfax (sometimes its on there) if you cant find out then plan on replacing it. Thats the only thing I dont like about them is the electric water pump. Mines still on the factory one at 80k miles. I have a new one still in the box I keep in the hatch area. Going to change it "one of these days" :)


Last but not least get a p3 gauge.


https://www.p3cars.com/bmw/


Its what the car should of had from the factory. Everyone that see's it goes nuts over it. I kind of take it for granted since Ive had it so long. I leave it set to showing water temp.


I shot a video of it in action here :


https://www.youtube.com/watch?v=XFpu8ODQFgI


The cruise control is cool on these too. It uses the brakes to maintain speed and the led shooting around the outside of the speedometer is cool.



https://www.youtube.com/watch?v=mp5xUPSXre4

My M54 other than oil leaking was a perfect running engine up to 205k mi. I don't have enough info on the longevity on the N55 but as mentioned never test drove any car ever (dozens) where the engine started and idled and drove as smooth.

Pulling codes there were a couple in sub systems like something to do with back seat lighting: enough to know the dealer didn't just clear the codes and no red flag like being disabled but the TC has oil wear code so I already ordered the new fkuid and plugs. I've done that fill job on 08 328xi.

While I'm down there I'll figure out where the emergency neutral screw is so I can drill a small hole and have access to that in case of emergency without removing the main underbody panel!

Once I know that info I will share with the E70 group so they can just measure X,Y and drill a hole to copy me.

I have a special method to make such an access hole don't want to spoil the surprise so I'll wait until I do it when I make my thread

The N55 is definitely less reliable than the M54. But N55s are cheap and plentiful and work well with an automatic. (The N55 is one of my top least favorite engines paired with a manual.)

This isn't a common issue, but if you ever have bizarre coolant loss / leaking at the back of the motor, I've seen the rear passenger head bolt back out. (Not strip out like an overheated M54. Just literally unscrew itself.)

From my experiences and from what Ive seen others have problems with the n55 seems to be the more reliable engine. I was writing a big long post of the problems Ive personally fixed on the n54's and stuff but Im just going to leave it as in my opinion a when not modified to produce a ton more power the n55 is the more reliable engine.

I haven't monitored E70 thread nearly as much as E53 so I may have just missed but other than the water pump and the belt ingestion concern I really haven't seen much to worry about. I do want to see 200-230k mi. with this car to get 6-7 years out of it like my 01.

Andrew, you won't be disappointed with that N55. I've already put 20,000 miles on mine in the last 11 months and it has performed beautifully. Ample power (can't tell you how many times I've been in triple digits passing), amazing fuel economy, and a nice intake growl. Not a drop of oil consumed or any coolant lost.


The 8 speed plays a big role in that performance and I have yet to encounter a situation when it didn't seem to match the ratio perfectly to the throttle demand. Now being the ZF though instead of the GM 5L40-E, I will perform their recommended fluid changes.

Congrats Andrew! Looks like a peach.

In my experience, admittedly none yet with the N55, all BMW engines are fairly reliable when maintained properly and preventative work is done. Doing that will cost more money/time on some engines than others (I'm looking at you BMW V8s and S motors), but all are fairly reliable. Again that's IME.

I was referencing the old M54 in our X5s, not the N54. The N54 is a tougher engine for big power, but it's definitely a crankier bastard compared to the N55 for daily use.

(I will note that I think the N54 drives better with a manual, but that's not relevant here.)

I thought you posted that the N55 was less reliable than the N54.


But you said M54.

Yeah, I figured. :)