"Cam chain cover too hot to even touch"

[les 1]

I own a 2005 320 E90 . Its done 55,500 kms . 

recently an intermittent fault developed that was diagnosed as a faulty valvetronic motor and BMW changed it out for a new BMW part . 

  Now , before the car was returned , "BMW" rang and said that they are not happy as to how the vehicle runs (subsequently ) and would like to track down if there was some other fault that was causing the engine to lose power . 

  So, some days go by , and they contact me again , and say they think that maybe the cam chain had been "stretched " by the faulty valvetronic motor , and it was this that was causing the engine to loose power . 

  Their fix for that issue was to do something that sounded like they tinkered with the cam chain tensioner by "replacing a bolt . They called me . Come get your car we think we have solved the problem , drivee it for the weekend and let us know .

Well i drove it out of the dealership to do a round the block trip and take it home . Shortly into the drive warning lights cam up on the dash "the usual check engine light ' , then something that looked like an explanation mark and possibly and traction control symbol and then really quickly a noticeable miss , and plainly the engine was now running on 5 cylinders .

  I drove it straight back , with the alrm symbols up , and the engine running , and called them out of their workshop to fault find . 

  Subsequently , i heard in muted conversation , that the cam chain cover "was too hot to even touch " . Shortly there after an offer to take a courtesy car home for the weekend was made . So i did that .  

  Now , friends i am asking for your advice as to how to avoid being railroaded by BMW techs into believing somehow , that whatever has happened 'will be at my cost to fix " 

  So , it occurs to me that whatever they have done has caused the cam chain to get hot . Could the cam chain now need replacing ? what else could be damaged ? what do i need to look for when i make a surprise visit back to their workshop on monday . Has anyone ever heard of the valvetronic motor causing a cam chain to stretch ? 

   All advice and opinion welcome .

cheers 

les 

[Vass 702]

If, as you say, it is a 320i and is running on 5 cylinders then that's a substantial upgrade since they only came with 4 from factory...

Smartarsery aside, and at the risk of sounding like a broken record, the N46 engine that this would have come with is one of the worst things BMW has come up with in recent history. Some mechanics are known to flat out refuse to work on them due to how problematic they are. They're plagued with issues and are very rarely worth saving. Especially if you're paying someone else to do the work instead of DIY. And especially if that someone is BMW. You'll end up with a bill that's multiples of what the car is worth.

Did you pay them for the work of replacing the valvetronic motor out of pocket or was it some sort of recall/insurance arrangement? Did they offer you any feedback as to what the faults might be before proceeding with the work? From what I know the timing chains stretching is one of the many known issues on the N46 so I would think it weird if they didn't offer to change those out "whilst they're in there". That could be considered as an oversight and used as an argument against having to pay twice for labour I guess. But then again, I wouldn't be taking a car like that to BMW for engine work in the first place.

As for the cam cover "being too hot to touch", I wouldn't take that as much of an indicator of anything. BMW engines jut run hot in general. Mine runs just fine but even the plastic top covers are too hot to touch after a regular commute.

[les 1]

Great incites . thanks . maybe i should have said that  take 5 cylinder out put the 4 back ! 

I did pay them for the valvetronic change out . Didn,t much think about the engine series at the time , cause its only done a genuine 55.5 k kms . What the hell be wrong with an engine thats had one owner and only done such low K,s ? 

Nevertheless , that motor was in a far worse state after they tinkered with "something " .in the cam chain area.

Anyway , any advice as to what i am going to ask them when i turn up in the workshop monday ?