Diesel owners beware

[devlinsky]

Scary bedtime story, but here we go.

138k miles, M50d, all bells and whistles. Goes a little slow, so let's check. DPF expired, nothing on the dash, so it creeped under the radar. Due to mostly highway miles - DPF was almost empty, so coded out and in - car flies again. Or is it?

A week or two ago, another interesting symptom, again nothing on the dash - car starts normally, but starts to shake few seconds later, warms up and shaking is gone, so all good, but, since the effect of this shaking is like a heavy misfire, so let's chase the symptoms and fix this barge for good. Problem is - car needs to be ice cold to show the symptoms, so diagnostic is pretty difficult.

First suspect - injectors. Car had glow plugs changed recently as a precaution, maybe something disconnected, some seals maybe, some vacuum lines, fck knows.

Car connected, cold start, heavy corrections on cylinder 4, so we're good, let's take it apart and see what's what.

And here we are. Check the photos.

Car will be walnut blasted ASAP. Stay tuned, this is a developing story.

Diesel owners. Are you sure your cars have full power?

[gvarr03]

Originally Posted by devlinsky

Scary bedtime story, but here we go.

138k miles, M50d, all bells and whistles. Goes a little slow, so let's check. DPF expired, nothing on the dash, so it creeped under the radar. Due to mostly highway miles - DPF was almost empty, so coded out and in - car flies again. Or is it?

A week or two ago, another interesting symptom, again nothing on the dash - car starts normally, but starts to shake few seconds later, warms up and shaking is gone, so all good, but, since the effect of this shaking is like a heavy misfire, so let's chase the symptoms and fix this barge for good. Problem is - car needs to be ice cold to show the symptoms, so diagnostic is pretty difficult.

First suspect - injectors. Car had glow plugs changed recently as a precaution, maybe something disconnected, some seals maybe, some vacuum lines, fck knows.

Car connected, cold start, heavy corrections on cylinder 4, so we're good, let's take it apart and see what's what.

And here we are. Check the photos.

Car will be walnut blasted ASAP. Stay tuned, this is a developing story.

Diesel owners. Are you sure your cars have full power?

If you don't mind me asking.. you said mostly highway miles, how often do you change oil?

[devlinsky]

Previous owner used to change oil - on average - every 15k miles, I change every 6k.

[P1]

Could use a bit of scrubbing it seems.

[smyles]

Prediction: cleaning won't change anything.

[devlinsky]

Originally Posted by smyles

Prediction: cleaning won't change anything.

Why? Could you please elaborate a bit?

[smyles]

Why? You're going to walnut blast it anyway (and I'm absolutely not stopping you).

But I doubt your rough cold idle (?) issue is just because of that.

[gvarr03]

Originally Posted by smyles

Why? You're going to walnut blast it anyway (and I'm absolutely not stopping you).

But I doubt your rough cold idle (?) issue is just because of that.

Well, he is just starting out in that direction. Definitely would not hurt to walnut blast that stuff.

[RED_Y_]

For 140K miles it is not that bad IMO.

[devlinsky]

Originally Posted by smyles

Why? You're going to walnut blast it anyway (and I'm absolutely not stopping you).

But I doubt your rough cold idle (?) issue is just because of that.

Any constructive suspicions on the cold start rough idle would be far more than appreciated.

[gvarr03]

Originally Posted by RED_Y_

For 140K miles it is not that bad IMO.

That's what I thought too. Chain replacement is also due soon, I wouldn't wait any longer than 150k miles.

[devlinsky]

Originally Posted by smyles

Prediction: cleaning won't change anything.

You were right. Now what, where to look, any ideas?

[W37V]

Originally Posted by devlinsky

You were right. Now what, where to look, any ideas?

You said you changed the glow plugs, but did you change your injectors? Injectors tend to fail. Heck, I had 3 injectors replaced at 48k miles (~78k km).

[smyles]

Originally Posted by devlinsky

You were right. Now what, where to look, any ideas?

Well, any codes? I suspect it's injector related, so remove, visually inspect, if needed swap (with appropriate registration). Also wouldn't hurt checking hoses for vacuum leak. But again, w/o codes it's kinda shooting in the dark.

Also, re timing chain, before replacing it have it inspected. I mean the top one, i.e. remove the valve cover and check for slack. While it wont hurt replacing all 3, even with cheap labor it's still an expensive ordeal just because of parts (and remote risk of effing it up)

[devlinsky]

Originally Posted by W37V

You said you changed the glow plugs, but did you change your injectors? Injectors tend to fail. Heck, I had 3 injectors replaced at 48k miles (~78k km).

I have had them all checked - all good. There were corrections on cylinder 4, injectors were replaced and re-registered - still corrections, so the walnut blast was performed and corrections are gone. So seems like injectors are good.

[devlinsky]

Originally Posted by smyles

Well, any codes? I suspect it's injector related, so remove, visually inspect, if needed swap (with appropriate registration). Also wouldn't hurt checking hoses for vacuum leak. But again, w/o codes it's kinda shooting in the dark.

Also, re timing chain, before replacing it have it inspected. I mean the top one, i.e. remove the valve cover and check for slack. While it wont hurt replacing all 3, even with cheap labor it's still an expensive ordeal just because of parts (and remote risk of effing it up)

Injectors checked and swapped with registrations - all good.
Vacuum lines checked - all good.
No codes whatsoever.

Apart from timing chain - no clue what to check next. With almost 140k miles - shouldn't it be replaced anyway as a precaution?

[smyles]

If 140k miles is real mileage, then it's a bit early; however, in addition to the chains (there're actually 3), camshaft gears can wear too, which also affects the timing. So I'd check for that (using the same camshaft tool).

Btw, what's the status of the fuel filter?

[devlinsky]

Originally Posted by smyles

If 140k miles is real mileage, then it's a bit early; however, in addition to the chains (there're actually 3), camshaft gears can wear too, which also affects the timing. So I'd check for that (using the same camshaft tool).

Btw, what's the status of the fuel filter?

Fuel filter is brand new, it was replaced with all fluids and filter when the whole issue started. Walnut blast improved the cold start behaviour a bit, but - it's still bad.

What really doesn't fit in my opinion into the timing chain theory box is the fact, that once the engine warms up a bit, the issue is gone. Since materials like metal expand with heat, shouldn't that cause the issue to be even more visible?

Next week I'll talk to my BMW tech friend from the dealers to have this whole timing system checked. I'm getting a little worried with this issue, I don't even want to think of the consequences of the timing chain failure.

Random thought - can a fuel quality play a role here? I switch to premium diesel to find out.

[///MCollection]

I would pull the cover off the egr valve and manually push and pull it to see if it's jamming rather than returning on spring pressure

I've had cold start roughness when egr is letting gas in when the engine can't deal with it because it's jammed

[devlinsky]

Very interesting thought! I will have the whole EGR unit replaced next week or so, so I will report with the results. Thanks for the tip!

[Rasko]

I have the same problem , about egr ... last week i get new egr with cooler and intake manifold on service injury in bmw, but problem with rpm is still there ��

[devlinsky]

Another possible path - wrong glow plugs. I have new Beru plugs that generate an error (not visible on the dash) but Bosch is the right one - so tomorrow I will have the right one installed and we'll see what's what. There are at least three people affected with this issue, ffs we can track that down, how hard could that be?!