Watch the clip: Horrible clunk sound at startup N52 engine

[AlphaBetaX5]

Hello everyone new to bimmerpost forum,

I've been having this issue for quite several months.

During cold startups, a moderate to heavy metal to metal noise comes from the engine.
From VANOS probably!


2009 X5 3.0 xDrive
N52
94K miles
Oil and oil filter changed 10 months ago (and 15 months ago)
VCG (and OFHG and OCG) changed last year
Eccentric shaft sensor changed last year
Spark and ignition coils changed last year.
Air filter changed few months ago.
VANOS solenoids both replaced with new aftermarkets, didn't help .
Intake camshaft position sensor changed, didn't help.
Oil filter was inspected last night, seemed like it had lots of metal shavings.
Purchased a new oil filter , and will change the filter this afternoon.

Car has 13-14 mpg. Also average speed is 14 mph (all city driving)
Car is very sluggish when the noise happens! Extreme hesitation after the clunk.
Also it appeared that mu intake vanos solenoid had leak. Fixed the leak.
Also it seems that the OFHG is leaking again, needs confirm.


Few days ago, and after a very load and firm clunk, code 2A82 was thrown.

Using ISTA+, cleared the code, and performed the VANOS solenoid test on both intake and exhaust. Both were OK.

According to ISTA+ possible root causes are:
1-low oil level (inspected and passed)

2-bad solenoids (inspected and passed)
3-loose tensioner belt
4-intake camshaft ledge seals.



I appreciate any input.

Has anyone had the same clunk sound at startup?
Has anyone experienced hesitation at low gears and cold starts?
Has anyone repaired the VANOS unit on their X5?


Thanks

[frankenm]

Get your engine inspected by a professional bro ... and get it towed there ... stop driving this.

[carbonM]

Is this only when the car is cold? Does it make the noise on every start?

[AlphaBetaX5]

Originally Posted by carbonM

Is this only when the car is cold? Does it make the noise on every start?

Only cold starts.
On cold starts, it's intermittent. Sometimes no clunk. Sometimes a moderate, sometimes a hard laud clunk.




My possible root causes:
1- Faulty Solenoids. Although they passed the VANOS test performed using ISTA.

2- Camshaft ledge seals of the VANOS assembly (Per ISTA: Plain Rectangular Compression Ring). Possible root cause :

3- Bad Connections - Inspected and confirmed in good shape.



4- Bad engine oil quality - I simply don't think so! It hasn't been even 4 K since last oil change. close to 10 months. Bad oil quality can be a symptom.

Changed the oil filter yesterday. It was dirty, and full of some stuff, that didn't look like metal shavings.
I will inspect it using a magnet to confirm.

With new oil filter, hesitation is GONE. Car is agile and very responsive.
Though the clunk was present this morning.


5- Low engine oil level - Confirmed via iDrive that level is O.K.

6- Missing Oil Filter Cap Insert.
Inspected it. I see only one small o ring:


And I don't see any o ring on the bottom of the cap. See attached picture. Needs more research.





7- Loose serpentine belt. Need more research here!

8- Dirty and clogged VANOS check valves (non return valves). Needs inspection. This also can be a symptom.

9- incorrect Valve Timing. It is very possible that my VANOS timing needs a reset.




Of all above, only 2 and 9 seem a bit intrusive to me! All other simple inspections will be done during this weekend.


So technically my root causes can only be 2, 7 and 9.
Camshaft ledge seals, loose serpentine belt, and timing!



Any input is appreciated.

[carbonM]

Thinking about this more, it could be the camshaft seals or solenoids could be bad. The original seals I think are steel, you could be hearing the noise initial when the camshafts start to rotate upon engine start.

[AlphaBetaX5]

Originally Posted by carbonM

Thinking about this more, it could be the camshaft seals or solenoids could be bad. The original seals I think are steel, you could be hearing the noise initial when the camshafts start to rotate upon engine start.

This is a possible scenario.

However nothing explains why it is intermittent.

I cannot replicate it even on cold starts. I can have the sound on the first startup, and not on the second,
or can have it every time!

I replaced solenoids (used new aftermarket ones), didnt help!
When I perform the VANOS Solenoid test on ISTA, it passes.

If you listen to the startup sound again, you'll notice it happens almost one second after startup. The engine is already ON, then the sound happens.

I have searched on many forums, and have not found this sound on any other BMW or any other makes!



This sound started developing last year when I changed my VCG. During that job, i removed the valvetronic motor. and just inserted it in when reassembling.


Later when I had to replace the eccentric shaft sensor, I noticed the the wormgear of the VVT motor show some signs of impact. Noting critical, it just caught my attention. (reason for ESS change was to cure hesitation, which didnt)


I used ISTA to have VVT motor to learn its end points several times. Which never improved the sound.

Hesitation was intermittent too!

After I changed my oil filter two days ago, hesitation is gone. the sound? still there!

I just inspected the check valves (non return valves, AKA vanos filters), they were clean! I cleaned them anyways and reinstalled. I dont think it will have any effect.


Now I have narrowed it down to:
1- Intake Camshaft ledge seals,
2- Valve Timing,
3- Loose Central Bolt,

I am neither technically nor mechanically nor logistically equipped to perform any inspection for these!



Before taking it to an indy, I might remove the Valvetronic motor and install it again!

Does anyone follow a specific procedure to reinstall the valvetronic motor?


Any input is really appreciated.

[carbonM]

Check for the procedure here: https://www.newtis.info/tisv2/a/en/e...ear/1VnXxK6FxK

[carbonM]

Are you sure the noise is coming from the engine area? Just wanted to double check since it's hard to tell from the video.

[AlphaBetaX5]

Originally Posted by carbonM

Check for the procedure here:
https://www.newtis.info/tisv2/a/en/e...epair-manuals/

Thanks so much,



I am going to remove and re-install the VVT motor per newTIS procedure and will report back.


https://www.newtis.info/tisv2/a/en/e...ear/1VnXxK6FxK

I have not turned on the car since yesterday, I should be able to try the cold start after this procedure.

[AlphaBetaX5]

Originally Posted by carbonM

Are you sure the noise is coming from the engine area? Just wanted to double check since it's hard to tell from the video.

Yes,
Confirmed.

I asked a the same question on other forums, and some folks thought it is from the clutch , and can be avoided if parked inclined.

I recorded several video , while phone under the car close to transmission, and in the engine area.

The sound is from engine area.

[carbonM]

Fingers crossed its just servo motor and not something more serious.

[AlphaBetaX5]

Originally Posted by carbonM

Fingers crossed its just servo motor and not something more serious.

A very small piece of the worm gear is chipped.

Not new, just like last tine I saw it and caught my attention.


The intermediate shaft has marks on it, which I think should be normal.


Going to install it now and start it.

[carbonM]

So it was like when you removed it before? That's a decent size piece of metal missing from the shaft. Probably a long shot, but did you look inside for any loose pieces of metal?

[AlphaBetaX5]

Originally Posted by carbonM

So it was like when you removed it before? That's a decent size piece of metal missing from the shaft. Probably a long shot, but did you look inside for any loose pieces of metal?

Yes.


Yes I did. Nothing was loose. None of the intermediate shafts teeth were chipped or missing, when I touched the gear inside.

Assembled now. Going to record a video of the startup.

[AlphaBetaX5]

No clunk in two attempts!!

I was absolutely expecting a sound, after car sitting for longer than 24 hours.

After removing and re-installing valvetronic servomotor per NewTIS procedure:

upon starting the car, a vibration was felt. waited for 10-15 seconds on the first start. I thought car is adjusting the wormgear or something.

It didnt get better. RPM was fluctuating 1100-1200, needle was not solid standstill.

turned it off.
turned it on again, same vibration existed. and car threw a CEL. turned off.

Now I'm going back with ISTA to scan it. I assume a misfire as a result of an incorrectly seated ignition coil.


Will update.

[AlphaBetaX5]

CEL was a misfire. Re-seated coils. Gone.






Then attempted several startups:

-No Clunk Initially: it appeared that the laud clunk is gone. No sound on the first, second, and third startups.


- Clunk is back after 10 startups, I started hearing the clunk again.
It seems like that it gets worse as I was performing more startups.

- Clunk exists even after VVT relearn on ISTA: Service Function: Learn Valvetronic Limit Position performed.



- I decided to have ISTA read the angel, and manually spin the VVT wormgear and see how it changes in terms of eccentric shaft angle:
- I noticed when ISTA performs the relearn, numbers are: Setpoint:60, Actual: 68

So I adjusted the wormgear using the hexagon socket wrench on the back of VVT motor, while it is installed, and since ISTA was reading the angle in realtime, I adjusted it exactly to 60!

Then started up! no clunk of whatsoever!



ISTA was reading in realtime, and I went for a spin. I noticed that the actual angel is gradually shifting away from the setpoint.
By at least 7 degrees and up to 15 or even more (couldnt really watch it as I was driving!


The higher the difference of setpoint and actual, the more vibration I could feel.




- Manually adjusted the VVT to match the setpoint again, started up, no clunk, but started feeling the vibration as the difference was getting bigger!


I recorded ISTA operations as a video:

Conclusion:
0- and most important one: It is not VANOS!
1- My eccentric shaft angel is 7-8 degrees OFF!
2- The vibration is the result of the difference between actual and setpoint angle of eccentric shaft. The bigger the difference, the more noticeable the vibration.
3- When there is a difference, the startup clunk exists.
4- the difference gets bigger and stops at 7-8 degrees. idle or in motion makes no difference.



My possible root causes:
1- Valvetronic servomotor.
2- Eccentric Shaft Sensor.
3- None of the above!
4- All of the above!



Notes
-I changed my eccentric shaft sensor a while ago. (exactly 6 months ago) Reason: Fatigue engine, hesitation, and it had oil on the sensor. Nothing improved after the change. I purchased a VDO sensor. (I believe it is OE). Still have the old sensor (Siemens).

It is highly unlikely that the sensor is the culprit. After all it is only reading the value of shaft rotation.


- Valvetronic Servomotor! Yes, it can be! this part is responsible for rotating the shaft. I need to do more research on this part.



Any ideas? Thanks in advance.
I am out of idea! this never ending diagnostics is taking too much time!

[carbonM]

Since the shaft has damage to it. I'm going to say that its the reason. I don't see any harm in replacing it anyways since its damaged and when you did adjust it properly it wasn't making the clunk noise.

[AlphaBetaX5]

Originally Posted by carbonM

Since the shaft has damage to it. I'm going to say that its the reason. I don't see any harm in replacing it anyways since its damaged and when you did adjust it properly it wasn't making the clunk noise.

Yea, I was looking at the pictures of the eccentric shaft now.

Teeth are scratched.
And the VVT wormgear is chipped.

I'm going to conclude that the worm gear skips either the very first tooth, or the last one. One half revolution of the wormgear corresponds to 3-4 dgrees on the eccentric shaft. (I did measure this yesterday when I was manually adjusting the wormgear/eccentric shaft.


So it makes sense that the chipped tooth skips, and is responsible for the 7-8 degree off. (Equals to two half revs of the wormgear per my field observations).



Also the scratches don't help the VVT to move the half moon gear on the shaft back and forth smoothly.

So my final conclusion is:
Change VVT Motor and eccentric shaft!


Thanks for your great help CarbonM, I will update this thread once I get these parts changed.

[AlphaBetaX5]

I replaced the VVT servomotor with a brand new VDO continental (from ECS tuning).


Have not started the car yet. Instead I did the ignition on /off cycle a few times and noticed the servomotor initial adjustments are quite noisy and noticeable. (Compared to the old servomotor).

The click sound upon turning on the ignition is, I think, the adjustments. The sound afterwards, is still the same sound I could hear when the old servomotor was installed. The second sound is like the camshaft returns back to its point, therefore skipping the wormgear teeth.


Is this normal?!

[carbonM]

Originally Posted by AlphaBetaX5

I replaced the VVT servomotor with a brand new VDO continental (from ECS tuning).


Have not started the car yet. Instead I did the ignition on /off cycle a few times and noticed the servomotor initial adjustments are quite noisy and noticeable. (Compared to the old servomotor).

The click sound upon turning on the ignition is, I think, the adjustments. The sound afterwards, is still the same sound I could hear when the old servomotor was installed. The second sound is like the camshaft returns back to its point, therefore skipping the wormgear teeth.


Is this normal?!

I believe there is a programming procedure when you replace the VVT. It sounded like it did rotate correctly at first, but then I definitely hear some sort of grinding.

[AlphaBetaX5]

No success!


Replaced the VVT motor, allowed ISTA to make the servomotor calibration and relearn end points.


Started up the engines. First attempt, no clunk.

After few times, the clunk came back!

$$$ wasted on a new servomotor.



(In meantime changed OFHG and OCG, due to a small leak, changed the o-ring of the thermostat-to-cylinder head hose, as it broke when removing it to access that bolt under the Oil Cooler!)


I checked the actual angle, and set point angle of the shaft after new servomotor installed.


Same as the old one, when the set point is 67, the actual was 58 degree. (Or the other way around).


So I think VVT servomotor is not the root cause.
I don't think the eccentric shaft is the issue either.


On thing I've noticed is that when I park slightly uphill ( the front of the car is raised compared to the rear), the dread clunk does not happen.


Cannot troubleshoot furthermore!

[AlphaBetaX5]

Originally Posted by carbonM

I believe there is a programming procedure when you replace the VVT. It sounded like it did rotate correctly at first, but then I definitely hear some sort of grinding.

I checked with ISTA, and didn't see any instructions for programming. It appears that it's R&R!