[junkyalleycat]

x3 suddenly displayed drivetrain malfunction, and low pressure warning, engine shut off automatically soon afterwards and I coasted down my driveway.

I was able to turn the engine manually so I know it isn't frozen, removed the oil cap and it didn't smell burnt, I had the car towed on a flatbed to the Seattle BMW dealership.

They sent me a video where the mechanic reached his finger in through the oil port and was able to move the chain a bit with his finger, implying that it is too loose. They gave me two options,
A) Simply replace engine (not worth it, replacement + labor probably equals the value of the car)
B) For $3700, remove the valve cover and inspect the chain to see if engine is serviceable. No parts or fixes in this price.

$3700 to REMOVE VALVE COVER and DECIDE if it's worth fixing!?? I clarified this with Seattle BMW multiple times, it's literally just to remove the cover and check the chain (+ replace gasket), and get an idea of the problem.

Car is ~10 years old, 80k miles, regular (every six months) oil changes. This is insane, obviously gives me no future interest in the brand.

I'm writing this I guess partially to hear people acknowledge that I'm SOL, and partially because I'm hopeful I get any scrap of advice that helps me to not accept that this 10 year old car with <100k miles is a brick.

[deathmetal666]

Take it to an Indy. I had my timing chain replaced for $3500. I have a 2015 328i.

[Opie55]

So long as your timing chain guides have not exploded and been sucked into the oil pump and starved the engine, then a new assembly should fix you up. As for the video of the loose chain, that can be honest or dishonest. If I walk out to my 2014 right now after it's been sitting all night, the chain will be quite loose. If I start it up and let it run a minute and then shut it off, the chain will be tight as a drum. Your chain has a hydraulic tensioner that tightens as oil pressure builds, and then it slowly bleeds that pressure off after the car shuts down.

[BohMotorWorks]

Concur with the thoughts above, $4000, at an independent shop should get you new timing chain, new oil pump chain, new guides, new tensioner, etc.

With these parts you shouldnt have to worry about it again until 200k miles.

Yes dealerships are always completely insane, they make their money repairing cars and convincing you to buy new ones.... not offering economic service. You can curse the brand we love because they are good cars, or you can realize every car company does this....

Again you have a $4000 repair on a 10 yr old car, not ideal, but sure beats buying a new $50k car.

[atl5]

Agree with everyone here, take it to an honest indy shop. My 2013 x3 broke down last year during boxing day. Took it to my mechanic and $4000k later, it was fixed, this is CAD pricing as well. So $3800 seems very steep just to inspect it.

[Bilbofraggins]

Only at Top dead Center is the chain at its tightest (no play)… most of the time checking through the oil filler cap you will encounter play… its tough to figure out what is excessive that way…

Tell the dealership to go f themselves and take it to a reputable indy…

[pungo]

Originally Posted by Bilbofraggins

Only at Top dead Center is the chain at its tightest (no play)…

The chain is tightest at TDC, really, please explain....
Opie55 explains it the best about the hydraulic tensioner and how it tightens the guides when pressurized.

Probably a moot point now since it appears many of these one post wonders, post, then leave the building

[Opie55]

Originally Posted by pungo

The chain is tightest at TDC, really, please explain....
Opie55 explains it the best about the hydraulic tensioner and how it tightens the guides when pressurized.

Probably a moot point now since it appears many of these one post wonders, post, then leave the building

I had the same reaction - how the heck does TDC affect chain tension? Think of the noise that engine would make.

[Bilbofraggins]

This is my lads 2015 X3 XDrive 28i. A couple months ago for ‘PM’ - we did the Timing/Oil Pump Chain at 150K (Km). There were no codes or problems - checking through the oil filler cap - things seemed fine. The two pics show the chain tension differences as the engine was rotated:

[Opie55]

The chain is loose in both photos. In the top photo the finger shows the slack, but note how where the chain leaves the left gear and spans the small gap onto the guide it is tight because his finger is puling up the slack all along the chain. But in the bottom photo the chain droops down on both sides where it spans the gap between the guide and the gears. Without a finger pulling up the slack in pic 2 there is no way to compare the amount of slack in both pictures, but I'm pretty sure it would be the same.

[Opie55]

And I will also note that based on stamping marks and bolts locations, etc, the cam gears are in exactly the same location in both in photos. Plus, you can clearly still see the chain impression in the guy's finger in photo 2, so these 2 pictures were taken just seconds apart without rotating the engine at all.

[tom2021]

Most reported failure was on the plastic chain guide.
Is the orange/brown thing the chain guide ?

[Bilbofraggins]

I wasn’t with my lad and his very skilled mech friend when they took the pics…and put 2 and 2 together when they said “all was tight at TDC”.. I assumed those pics told the story… but I can see your point….
As for chain tension at TDC and other positions…this is a good write-up and similar to how it was on my lads vehicle…

https://mazdaspeeds.org/index.php?th...-at-tdc.10244/

[slowblackx3f25]

Originally Posted by BohMotorWorks

You can curse the brand we love because they are good cars, or you can realize every car company does this....

This. Is. BIG FACTS!!!! Every car company does this... you guys haven't heard about Audi/VW/Porsche problems....

[Opie55]

Originally Posted by tom2021

Most reported failure was on the plastic chain guide.
Is the orange/brown thing the chain guide ?

Yes, part of it. The guide goes way down towards the bottom of the engine. That where it breaks.

[Opie55]

Originally Posted by Bilbofraggins

I wasn’t with my lad and his very skilled mech friend when they took the pics…and put 2 and 2 together when they said “all was tight at TDC”.. I assumed those pics told the story… but I can see your point….
As for chain tension at TDC and other positions…this is a good write-up and similar to how it was on my lads vehicle…

https://mazdaspeeds.org/index.php?th...-at-tdc.10244/

I can't speak to Mazda engines, and the only explanation was that it "has to do with WT." No idea what that means. But if a BMW tech said that, I'd like to hear the explanation. It's a chain running over round gears. What is it about TDC that changes that relationship?

[Opie55]

And if I had to guess, when they rotated the engine, the tension of doing that put the slack elsewhere in the chain - in one of the legs leading down, so they thought it was tighter.

[Bilbofraggins]

I was hoping you might have heard of the WT abbreviation noted. But what was interesting is the fact of some chain slack during rotation is normal to them and may be on this engine…the question is - why would that be - if the tensioner was doing its job.

At the end of the day, that is what was observed, but now wondering how much play is normal, with intact guides before it jumps a sprocket.

This was a PM job - and one we took on (was it unnecessary-hard to say) - we also included: plugs, coils, filters, remaining fluid's, belt and tensioner.

[deyrag]

i think you both need new glasses LOL
it is V V T (variable valve timing)

[Bilbofraggins]

Originally Posted by deyrag

i think you both need new glasses LOL
it is V V T (variable valve timing)

Probably...and yes VVT.....but what is WT....as mentioned...Does it matter,,,likely not...

[simple_vinay]

Hi

I am having the same issue for a few weeks now.

Whenever I stop the car and turn-off the engine, Its shows a drivetrain warning, I took it to the local garage and they did a full scan but couldn't say anything conclusive, any suggestions ? I have uploaded the pictures of what I am seeing ( and I not a car expert ) .

[junkyalleycat]

Hey all, thought I would drop some information here about the progress, pretty cool to see so many responses.

After BMW Seattle told me 3700 to take the valve cover off, I called a couple of indy shops which both told me that if they did do the work to diagnose the issue, that if it was engine related they wouldn't work on it. I ended up towing the vehicle home again to see what I could do.

I did a bit of research and discovered that this engine, the n20, has a fatal flaw that impacts customers around 70k-100k miles, where the timing chains slaps against the guide enough that the guide cracks, possibly leading to catastrophic engine failure.

I removed the valve cover in about 3 hours (again, bmw seattle charges 3700 for this) and quickly discovered that the chain guard had broken, a large piece of it is visible in the chain well, though the chain tension still seems ok.

I've separately tested the compression on all of the cylinders and it seems ok (just manually cranking the engine and feeling it compress a good deal), and have also scoped the engine out and did not notice anything obviously shredded in the cylinders.

The plugs were all carbon scorched which I thought was odd, but other than this and the broken guard nothing else looked off to me. I drained the oil and it was clean, and the filter was clean too. I plugged a computer into the ODP port and, besides it being upset about the car being jacked, nothing else was reported as wrong except the valvetronic sensors, which I believe was due to me having it unplugged when I ran the initial ODP scan.

At this point, I've positioned an engine support bar above the n20 and jacked it up about an inch to give me clearance on the underside to remove the pan for deeper inspection. Removing the CV joints was surprisingly easy, which was required first.

My hope is that once I pull the pan, I can visually determine whether or not the engine is possibly salvageable. This would mean reassembling the chain guide to see that none of the parts are missing, and replacing the cog/chain/guide with the updated n20 parts that were released to overcome the fatal flaw in the engine.

If you have an n20 from 2013 or around that time, please be aware that you might be sitting on a ticking timebomb. There was a class action lawsuit for this that has sadly already been settled.

Attached are a few pictures showing what I'm working with, a shot of the broken guide, and shot of me pulling on the center of the chain (I didn't try to find top dead center or anything), and another of the engine being hoisted. Appreciate all the points dropped in this thread so far and any others that folks can provide. I've never worked on engines before so am especially eager to here about gotchas and things to look out for (for example, making sure to mark the joints and drive shaft before removing). Thanks!