[kevink1]

Just the potential timing chain issue brought up many times.

I'm driving a 2015 X28d, and recently went past 92K miles. Still haven't had to do the brakes, though the car has been telling me I'm within 4000 miles for the last 3 years.

I'm considering transmission fluid replacement/transfer case fluid, since if those items fail it is expensive. The transmission manufacturer says change at 62K miles.

I've been paying $800/month on my car for the last nearly 7 years. When it was paid off, the money has been going into an emergency fund I do maintenance out of and will be used on next car.

[dave14x28]

My 2014 X1 w/N20 has 86k miles. I bought it from a 3-year lease CPO, and it's been a good car so far. Concerned about the timing chain issue though. My production date is in 2013 so it did not get the upgraded timing chain, guides, tensioner, and oil pump drive assembly.

Check out FCP Euro's two timing chain DIY YouTube vids, you'll learn a lot just watching!

Also read the Gelis et al lawsuit for some good descriptions and photos of the problem and BMW's redesigns.

A few observations so far:

The sound of a bad timing system is difficult to quantify unless it's really bad. On my car, sometimes I can hear something, sometimes I can't, but my hearing isn't what it used to be. It seems to be a higher frequency, sort of a wet or slushy hissing sound (the sound of loose links slapping plastic guides and steel sprockets bathed in oil).

Regarding timing chain slack and polish/scoring - slack seems to vary randomly for me, as well as for many others! But looking at the timing system assembly and how the tensioner works (it has an internal spring in addition to the assist from the oil pressure), and knowing that BMW redesigned it to have more travel and more spring force, it seems wrong that there should ever be significant slack up top between the two camshafts. I would expect to be able to wiggle the chain back and forth or up and down maybe 1 mm or so, but no more. On one occasion, I could have gotten my pinky finger under it if the oil fill opening were larger. That much slack means the two camshafts are not in time until the slack is taken up! The guide that you can see through the fill cap does flex a little, but I've seen videos where it appears to be very loose - I would assume those ones have broken at their mounts.

The tops of my chain links are partially polished - the only thing the top surface of the chain should touch is the tensioner guide itself, and I'm surprised the plastic can polish the metal. Gee, I wonder what condition the plastic is in??? Time for a borescope...

If the plastic guides begin to break and actually move away from the chain, it will add to the slack in the system which the tensioner is supposed to take up. Same is true if the chain "stretches". BMW has a special tool 2 411 399 that installs in place of the tensioner to measure for "elongation" per TIS procedure 11 31 540; the measurement would also be affected if guides are worn or have moved out of position (i.e. broken). Why there is not much talk of this in the forums I don't know.

For those with engines covered by the Gelis class-action settlement on 2/16/2021, the challenge will be to catch a failure that is in progress before it goes catastrophic.

Any bright ideas anyone?