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Discussion Starter · #1 ·
OK, so a few days ago I visited my mechanic and there was an M5 in there with its engine out. Turned out that this 02 M5 with less than 50K miles had a huge VANOS failure which caused about 6K of damage. It happened while he was driving.

I did a search and did not see a test to see any preventive maintenance or testing procedures for the VANOS. Being a guy with an 03 and 38K miles, I am paranoid that I am going to end up being like this unlucky 02 guy with only 50K miles.

Is there a test or something I can do to proactively make sure that I don't end up with a 6k repair bill?

Thanks!
 

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I'm fairly new to the M5 but I've already had to replace o-rings on the solenoids. As I understand it there's not a whole lot you can do to test it specifically. I would have to know exactly what happened to the other M5 to comment in detail but I would guess if it was the vanos, it was in bad shape (and ignored) for quite a while. I think the vanos itself is pretty bulletproof. It does operate under extreme pressures but they are isolated. It could cause an extreme lean condition, but the DME should be correcting for that to some degree.

What I plan to do is periodically check the fuel usage ("MAF") test and head problems off early. I can also check fuel trims stft and ltft on my obdII scanner. If neccessary, the GT1 can do a general check of vanos operation and verify solenoid function.

HTH

dj
 

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The exact reason would help alot.

Even if a unit fails completely,the valves do not touch the piston.

Big damage can only happen if the bolts of the sprockets back out,but this is way more common on S54s than S62s...

To check the bolts,the valve covers have to be removed and the bolts tightened with 10NM.New bolts from BMW come as 10.9 strength,the original ones are 8.8.

To change the bolts,the Vanos units and upper chain covers have to be removed.
I always use Loctite medium in addition to keep them in place.

The other thing that is possible for the damage on the mentioned engine is main chain guide failure...
 

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Discussion Starter · #4 ·
The exact reason would help alot.

Even if a unit fails completely,the valves do not touch the piston.

Big damage can only happen if the bolts of the sprockets back out,but this is way more common on S54s than S62s...

To check the bolts,the valve covers have to be removed and the bolts tightened with 10NM.New bolts from BMW come as 10.9 strength,the original ones are 8.8.

To change the bolts,the Vanos units and upper chain covers have to be removed.
I always use Loctite medium in addition to keep them in place.

The other thing that is possible for the damage on the mentioned engine is main chain guide failure...

I am not really knowledgeable on the engine/VANOS, IIRC, the guy was driving, then massive loss of power, check engine light came on, he stopped the car, had it towed. Some valves were bent, the chain guide was in a few pieces.
 
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