BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
Go Back   6Post.com | BMW 6-Series Forum > BMW 6 Series Forum > General 6-Series Coupe, Convertible, and Gran Coupe Forum

Post Reply
 
Thread Tools Search this Thread
      10-10-2020, 10:44 AM   #1
Wanwansuii
New Member
United_States
5
Rep
22
Posts

Drives: '14 BMW 640i Gran Coupe Msport
Join Date: Oct 2020
Location: Northern California

iTrader: (0)

N55 engine and concerns w/preventing engine failure

Hello all,

So for the past few days, I have been lurking on the F10 5 series forum to see what issues I may come across with the N55 motor since there are way more 535s than 640s. As we all know, the N55 is known for issues surrounding and/or increased maintenance of valve cover gaskets, spark plugs/coil packs, water pumps (a long-standing BMW problem), and the notorious OFHG.

In my research, I'm finding several motor seizes that eerily occur several miles after the replacement of the OFHG, which does put some fear in me. Supposedly, from what I'm reading, it seems like the cause is an air bubble that develops in the oil cooler during the OFHG replacement, and supposedly the oil pump should be primed three or so times before restarting the engine after the procedure to properly lubricate the internals.

This is a bit concerning since I drove my N52-powered E92 coupe up to 200,000 miles with minimal to no issues and not a check engine light in sight; and the engine sounded and performed just like new. OFHG went at 175,000 miles and only took 40 mins to replace, and drove completely fine afterwards.

While I know that the N55 is generally considered much more reliable than the N54, what are all of your thoughts/experience/knowledge on this? Is this something 640i owners should be concerned about? Have you had any issues surrounding this?

I'm thinking of using Liqui-Moly 5w-30 oil going forward.

I will post a few links that allude to all of this!
Appreciate 0
      10-10-2020, 02:55 PM   #2
Derekz4
Second Lieutenant
121
Rep
253
Posts

Drives: BMW 640i. BMW Z4,01 Bullitt
Join Date: Jun 2019
Location: Southern California

iTrader: (0)

I’ve read a few of the posts you are referring to, I’m not sure I would worry about it. I have slight concerns with serpentine belt failure and getting sucked into the engine but I’ll change it out more often.
Appreciate 0
      10-11-2020, 12:15 PM   #3
Frupal
Mad Fiddler
United_States
424
Rep
630
Posts

Drives: 2016 BMW 640i GC
Join Date: Apr 2019
Location: Los Angeles

iTrader: (1)

Quote:
Originally Posted by Derekz4 View Post
Iíve read a few of the posts you are referring to, Iím not sure I would worry about it. I have slight concerns with serpentine belt failure and getting sucked into the engine but Iíll change it out more often.
When should one change that serpentine belt? Iíve got about 44k, now...
Appreciate 0
      10-11-2020, 12:56 PM   #4
Opie55
Captain
302
Rep
954
Posts

Drives: '15 650i Convertible
Join Date: Apr 2018
Location: US

iTrader: (0)

Quote:
Originally Posted by Frupal View Post
When should one change that serpentine belt? Iíve got about 44k, now...
Modern serpentine belts are made to last like 100k, but they are easy enough to change on your engine I might do it at 60k or so. On a 650 it is literally a challenge just to catch a glimpse of the belt there is so much stuff up front.
Appreciate 0
      10-12-2020, 10:44 AM   #5
Frupal
Mad Fiddler
United_States
424
Rep
630
Posts

Drives: 2016 BMW 640i GC
Join Date: Apr 2019
Location: Los Angeles

iTrader: (1)

Quote:
Originally Posted by Opie55 View Post
Modern serpentine belts are made to last like 100k, but they are easy enough to change on your engine I might do it at 60k or so. On a 650 it is literally a challenge just to catch a glimpse of the belt there is so much stuff up front.
Thanks, Opie. Iíve got a 640, so itís probably a little less complicated. 60k is a great call.
Appreciate 0
      10-12-2020, 11:08 AM   #6
Derekz4
Second Lieutenant
121
Rep
253
Posts

Drives: BMW 640i. BMW Z4,01 Bullitt
Join Date: Jun 2019
Location: Southern California

iTrader: (0)

Yes, 60k would be a good number but you need to take into account oil leaking on the belt via valve cover gasket leaking. This will greatly diminish the life of the belt.
Appreciate 1
Frupal424.00

      10-12-2020, 01:44 PM   #7
Wanwansuii
New Member
United_States
5
Rep
22
Posts

Drives: '14 BMW 640i Gran Coupe Msport
Join Date: Oct 2020
Location: Northern California

iTrader: (0)

Thanks for this info! Who knew I would be more afraid of a drive belt snapping causing catastrophic failure simply because of an oil leak...I guess the best recommendation is to keep an eye over the condition of the drive belt (even at slightly lower mileage; mine is at 59,000k) and inspect for leakage.

Is it an involved procedure to change the belt? Even with the N55 it seems a bit tight in the front space.
Appreciate 0
      10-12-2020, 02:03 PM   #8
Opie55
Captain
302
Rep
954
Posts

Drives: '15 650i Convertible
Join Date: Apr 2018
Location: US

iTrader: (0)

Quote:
Originally Posted by Wanwansuii View Post
Thanks for this info! Who knew I would be more afraid of a drive belt snapping causing catastrophic failure simply because of an oil leak...I guess the best recommendation is to keep an eye over the condition of the drive belt (even at slightly lower mileage; mine is at 59,000k) and inspect for leakage.

Is it an involved procedure to change the belt? Even with the N55 it seems a bit tight in the front space.
I have not done it yet on any BMW, but I've done it on MBs and Audis. Whether you consider it involved depends a lot on your own skill level and experience. A lot of people would consider changing the air filter to be involved. As repairs go, I would not call it complicated. You are basically releasing tension on a spring-loaded idler pulley to give the belt enough slack to remove. How bloody your knuckles get doing that depends on how tight the clearances are.
Appreciate 1
Frupal424.00

Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 10:21 PM.




6post.com
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST