N20 timing chain rail coming apart

 Here’s a hot topic with a lot of BMW owners,,,,this car came in with check engine light on and engine whine and rattle noise,,,,check engine light was low oil pressure and jammed oil pressure ,,,,,I noticed the timing chain whine but the engine was also rattling,,,,I removed the valve cover to inspect the timing chain,,,,you can see the chain rail missing and jammed under the vanos unit. So I removed the oil pan to see what’s going on inside and this is what I found at the bottom of the oil pan,,,,there was so much plastic from the timing chain rail,,,there was also a broken bolt and metal shavings in the pan. There was so much plastic in the oil pan that the oil pump was sucking up pieces of plastic causing a oil pressure issue and causing more damage.

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157 Responses to N20 timing chain rail coming apart

  1. concerned says:

    Hi Andraes, has BMW field engineers offer any explanation how this whole mechanism failed? Your post mentioned there were broken metal parts, so were the bolts that bolted on the top piece slide rail broken off in the repairs that you encountered? Or the failure started at the two snap-on tabs that connect top slide rail to the right-side guard rail?


    • Most of the failures I have seen start with the two snap tabs for the timing chain rail breaks


      • concerned says:

        The N55 timing chain rails have similar snap tab design too, and N55 timing chain has not quiet made the news all these days ….

        From the N20 parts diagram, the top slide rail is bolted on by two bolts, the right guard rail also has 2 bolts. So the two snap tabs should not bear weight/force, correct? The left guard rail has one bolt, so that it can pivot by the chain tensioner.

        Did most of the failures result in shattered top slide rail? One speculation is that the factory torque spec of the 2 bolts for top slide rail are incorrect, leading to the failure. Is that possible?


      • We were told from bmw the problem is the timing chain weak link and the plastic was also weak,,,so they updated both and made them stronger


      • Aaron says:

        Hi there. I’ve just gone through this painful experience myself. BMW offered me 20% off a brand new engine. Still $17,000 for an x1 thatvisnt even worth that. Anyways I spend 20 hours replacing the chain. Big job. Went well and all seemed good. The car ran for a mile or so then seized. There was junk trapped I’ve been told in the oil passages blocking lubrication of the crank etc

        Found a low mileage used engine for $4800. You suspect these class action lawsuits will come to fruition? BMW must be accountable for this. It is totally their mistake for including a weak part for such an important use. I will never buy another BMW as they have not helped me financially and refuse to take responsibility.


      • You never know about these class action suits,,,I totally understand you leaving BMW


  2. concerned says:

    So BMW knows all along the early N20/N26 has weak chain link and weak plastic …. BMW better makes things right for their customers.


    • That why they did that 7/70 for certain models and years


      • concerned says:

        A dealer foreman listened to my N26(almost 7 years and 60k+ miles) and said there was no whine. He also opened engine oil cap and checked that the timing chain + slide rail(engine just turned off) was tight with no snag. My trusted mechanic also listened to the engine and said it sounded quieter than other N20/N26 timing chains that he fixed. The cold chain + slide rail has a slight play, maybe 1-2mm.

        My 7 yr/70k will expire end of this Oct(in a couple of weeks). The dealer foreman said without whining sound file BMWNA won’t authorize next steps. He did suggest to authorize diagnostics($200) so that the shop can dump car data to BMW headquarter to further evaluate. Do you think it is worth paying $200 to do this?


      • Nope,,,,I have never heard of car data for further evaluation,,,if they took a look and said everything looks ok,,,,I would hold on to my $200 dollars


  3. concerned says:

    Thanks for saving me $200!

    I have told the SAs and foremen to check timing chain in the past dealer oil changes, they just informally listened and looked, and said all was good. None of my complaints was on paperwork, the SA said to get the complaint on record, I had to pay $200 diagnostics before they will put anything on paper. Oh well.


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