E60 2008 550 Timing Jump

[tcdesignguy]

Moving to a new thread as I try to determine the following a catastrophic failure of the alternator bracket seal.

Facts about the incident.

1. Car quickly ran out of oil
2. Under acceleration heard a quick noise like I had a sudden hole in exhaust manifold.
3. Car shut itself off when it detected misfires bank 2 and exhaust cam timing 1 tooth error
4. Car passed leak down tests and compression
5. Observed exhaust cam timing isn’t lining up with intake
6. Borescopped down the chain to see no debris or damage in lower chain case area. Perfectly clean all the way down.

Now my questions

1. I’m ordering a timing tool kit, but as I wait can someone confirm what I think I see as the exhaust cam has jumped ahead ~40 degrees. (See attached image)

2. How can it jump this far and not collide with the pistons on that bank

3. Can I simply loosen the bolt at end of exhaust cam and use a wrench to turn the cams back into time and put car back together with new seals??

[dworthy]

Is this a N62 motor? There is known issue that most of the BMW V-8's have serious issues with the chain stretching and guide rails destroying themselves.

And is this Todd by chance?

[tcdesignguy]

This is Steve, it is an N62TU engine and I believe this engine doesn’t have as big of an issue. Timing chain is really tight, and everything looks good. Guides look good - with 0 debris perfectly clean chain area all the way to the bottom.

[dworthy]

I saw TCD and thought of Todd, and then later remember there was you as well.

I don't have a lot of experience with that particular motor, as there are several other guys who play with it all the time. I would get a set of timing tools and check, for typically the VANOS will only go +/- 20ish degrees on cams. What it looks like to me is one side if fully advanced while the other is fully retarded.

Lastly what does INPA or your diagnostic tool telling you about the cam timing?

[tcdesignguy]

The car doesn’t run long enough to get good live data. When the car first went down I have bank 2 exhaust cam timing code. After resetting codes, fixing the alternator bracket leaks and starting car for 10 seconds before it does it won’t spot out cam timing code - just misfire 5,6,7,8. So the system must need to run a bit longer to give that code is my only assumption.

[bmwdirtracer]

In my experience, timing correlation codes pretty much always set extremely quickly, on the second start /run of the engine. I am not intimately familiar with that engine, and certainly don't know, by a single photo, what some portion of the cams should look like. I use timing tools. Also, vanos motors don't usually "line up" without moving things, after they've run. I'm not saying your cam timing is correct, but I will say that if it skipped, you're going to need to do the entire job - new chain and rails, and tensioners, and the whole shebang. And then, of course, you'll have to hope the valves aren't bent.

Because you started a different thread, I can't reference your previous information, like whether you did leak down tests. Always a bad idea to spread the information out, rather than consolidate it.

[tcdesignguy]

I broke my threads into 2 groups. 1st was diagnosis of the problem. Part 2 moves to fixing the timing issue I most defenitley have. That valve cover job sucked, I would rather do alternator bracket job every time and I have all the oil coolers. I did give a thorough recap at the top of this post that included leak down test passed etc to make it convenient.

timing tools come on the 12th. I won’t be replacing all timing components, the car will get parted out before that. The plan is to set timing, check it after couple rotations. Replace seals as I reassemble. Clear codes and adaptations and start the car. Hopefully all is good. The timing jump didn’t cause any visible damage or wear to any components, and is understandable since tension was lost momentarily along a 12’ long chain under load.

[bmwdirtracer]

You asked how a cam's timing can jump by 40 degrees, and everything's still intact....well....valvetronic didn't let the valves open, because of timing misinformation. But, then, you don't have timing codes, so that blows that idea away. Timing correlation codes set extremely quickly during 2 starts.

More importantly, if the timing jumped by 40 degrees, how did this happen? The chain did not physically jump, on a single camshaft, because of the oil leak. Ah well, you'll find out soon.....

[tcdesignguy]

Ok I see what you are saying. I did originally have code for exhaust cam tooth offset. After clearing codes the first time, it just came back as misfires even though the timing has been off the whole time. Not sure why it doesn't know that its out of time yet unless you guys have any ideas. Seems no one has seen this exact set of failures on this engine before.

Also agree it seems ridiculous to think timing jumped on one cam. anytime I have seem this type of issue its because of a failed tensioner (destroyed to to lack of oil and chain slap) that didn't allow the engine to get back to time. Replace broken tensioner and re-time engine and good to go. Another note: with failed tensioner there was a little slack in the timing chain. Mine is super tight.

Imagine my surprise when I take this damn thing apart and all components look pristine with 0 evidence of component wear or failure other than the exhaust cam looks out of time. There is NO way I will we able to set the exhaust cam timing tool the way the cam is sitting. If the other 3 cams are perfectly in time, I guess this would tell me the failure would have to be in the vanos cam gear, or the adjustment unit or something specific to this cam.

Something has to be failed, and is still failed in order to the system to not pull back into time with adequate pressure. Would you agree or am I still way off?

[White94RX]

I've seen the cams move independently of the VANOS gear. There is no keyway locking the gear to the camshaft. The question is why. I had an N63 that was involved in an accident and jumped time. I could only assume that the trans and torque converter were locked, and abruptly stopped the engine in the collision, causing the cams to spin.

Break the VANOS bolts loose (you must use new bolts). Time the engine properly. Torque the VANOS bolts. Spin the engine a few times and recheck. Did you take off both valve covers? I for sure would check both sides. And make sure the cam is positioned properly, and not 180 degrees out.

[bmwdirtracer]

tcdesignguy: Listen to White94Rx; he's dealt with more of these motors, in depth, than I have. That said, there's no way that I would consider "partially" retiming the engine, either. You do it right, follow the factory procedure and use the proper tools...always!

[tcdesignguy]

Thanks guys, I'll pull valve cover off of Bank 1 do run the full timing procedure and report back!

[tcdesignguy]

UPDATE:

Got the timing tools to re-time the engine.
Went to loosen bolt on camshaft gear, and bolt and it wasn't super tight at all - like ~10ft/lbs if I had to guess.
I set the timing, rotated engine about 6x and timing is dead on.

Performed leak down cold engine (off for 2 months) @ 100psi -
Leak rate is great, no bent valves
cyl 5 -3psi (holds 97)
cyl 6 -6psi (holds 94)
cyl 7 -4psi (holds 96)
cyl 8 -3psi (holds 97)

I am under the impression that the camshaft ended up 30 advanced of the gear and either the bolt was a little lose before, or became a little lose because of it. It seams I got extremely lucky.

I do want to remove the sprocket, inspect for face wear, and ensure the 3 pins inside aren't bent. Is this process simply release the chain tension, remove bolt and pull the sprocket off? do I have to mark any positions for reassembly?

Thanks - Steve

[White94RX]

Nothing special. You've got it. Take out the tensioner, unbolt the gear and take it out. Doesn't have to be marked, they can be installed in any position.

[tcdesignguy]

Should be good to go now, no damage to vanos adjuster. new bolts for intake and exhaust adjuster, reset timing rotate engine 6x and timing is perfect for both cams. Intake cam bolt had not loosened and was in-time but decided to replace anyway and reset.

upper timing cover about done, then back to that crappy valve cover and rear firewall duct panel etc.

[dworthy]

Good to hear, did you put any lock tight on the new bolts? I wonder if that would keep it from happening again.

[tcdesignguy]

I did not. I haven't heard of this as a common issue with N62TU. The camshaft was 30 degrees advanced (clockwise) which would be the exact same thing as loosening the bolt (it isn't LH thread) 30 degrees. Not really possible for me to determine the root cause of the cam slip. Bolt could have been loose, or the slip caused bolt to be loose. I carefully reassembled the entire engine compartment yesterday with all new gaskets on bank 2, cleaned vanos solenoids and charged the battery.

Tonight I'm going to top off all fluids, hook up with ISTA and check all modules, and try to run valvtronic re-learn. Is there anything else I should do prior to starting up first time in 1 month? I put some oil on cam lobes and exposed chain before closing it up. I should probably turn it over without the fuel pump fuse in to re-prime oil pressure?>

[tcdesignguy]

UPDATE: ALL FIXED!!!! Thanks to everyone in this forum for your input over the last couple months. Cleared the 22 stored codes , cleared adaptations, learned the valvetronic limits and the car started at the push of a button. Idles so smooth I was able to balance a nickle while it was sitting there idling quietly.

Moral of the story - If you are leaking oil and suspect its your alternator bracket seal.. FIX IT. It can lead to catastrophic oil loss, and lead to major damage, or timing issues.

I still will never understand exactly how low oil caused my bank 2 exhaust cam to "slip" 30 degrees advance. The cam bolt was lose, so I don't believe the chain jumped, I believe the cam advanced ahead of the vanos adjustment unit (phaser).

Looking forward to more car adventures with this group!

Steve C

[White94RX]

Glad you got it fixed.

[tcdesignguy]

Me too! I was scared to press the button! haha -Thanks again guys.