Urgent Z4 Issue

[laurieballard]

Hey

So I bed the brakes and then went to start the car, she was in gear so duly jolted forward.

She then wouldn't start at all, just kept turning over. If I applied a lot of gas she eventually started but now sounds like a bag of sh1t and it not driveable.

This is a video of her idling:

https://www.youtube.com/watch?v=_hfJ9hXEgAg

What on earth have I done?

I don't understand what happened here. The ECU is throwing a Camshaft position sensor warning code but no others.

Thanks!

[mmm-five]

I don't know what's wrong, but I'd leave it switched off until you can arrange a tow truck to a reputable garage!

[parabolica]

Was it quite a violent jolt? If so it's possible something has dislodged or shifted in the engine. Agreed with mmm-five; keep it off until you can get it transported to an indy, or have a mechanic come take a look at it.

[laurieballard]

Yeah was a fairly big jolt. She was in gear on the drive which is sloped and it lurched forward when I started it up.

[Jembo]

Unlikely to have jumped a cog as believe it’s a chain cam belt - however, definitely a timing issue somewhere - I just hope u haven’t twisted something internal u shouldn’t to cause this

[laurieballard]

Mechanic is going to look at it this week but from the description, ECU error code and the fact its an N46 engine, he is almost certain the timing has gone out.

Best case its a re-time and likely replacement of the 'guides'? £350-£400.

Worst case its damaged valves and its strip down and rebuild time.

He seems to think the N46 engines have a reasonably common issue with their chain guides breaking so once this is sorted, I think she is going up for sale.

These older BMW engines (N42, N46, N47 etc) seem to have far too many chain issues considering what they cost. Don't get me wrong, all cars have known faults but rarely ones which tank the whole engine if they happen.

[MACK]

Mechanic is going to look at it this week but from the description, ECU error code and the fact its an N46 engine, he is almost certain the timing has gone out.

Best case its a re-time and likely replacement of the 'guides'? £350-£400.

Worst case its damaged valves and its strip down and rebuild time.

He seems to think the N46 engines have a reasonably common issue with their chain guides breaking so once this is sorted, I think she is going up for sale.

These older BMW engines (N42, N46, N47 etc) seem to have far too many chain issues considering what they cost. Don't get me wrong, all cars have known faults but rarely ones which tank the whole engine if they happen.

Your right about the N40/42 having a terrible reliability record and when it comes to to timing chain/tensioner/guide issues its more a case of when not if. On a more positive note the N42 is whats know as "a non interference engine" which basically means the valves and pistons cant come together so at least this shouldn't be a concern. Hopefully a new chain/guides/tensioner etc should put it right.

[Silverzedtom]

Was reading about timing issues on this engine in a mechanics magazine. Unfortunatley it seems fairly common

[laurieballard]

Mechanic is going to look at it this week but from the description, ECU error code and the fact its an N46 engine, he is almost certain the timing has gone out.

Best case its a re-time and likely replacement of the 'guides'? £350-£400.

Worst case its damaged valves and its strip down and rebuild time.

He seems to think the N46 engines have a reasonably common issue with their chain guides breaking so once this is sorted, I think she is going up for sale.

These older BMW engines (N42, N46, N47 etc) seem to have far too many chain issues considering what they cost. Don't get me wrong, all cars have known faults but rarely ones which tank the whole engine if they happen.

Your right about the N40/42 having a terrible reliability record and when it comes to to timing chain/tensioner/guide issues its more a case of when not if. On a more positive note the N42 is whats know as "a non interference engine" which basically means the valves and pistons cant come together so at least this shouldn't be a concern. Hopefully a new chain/guides/tensioner etc should put it right.

Hers is an N46, is this still a non interference engine?

Google suggests its not :S

[MACK]

Mechanic is going to look at it this week but from the description, ECU error code and the fact its an N46 engine, he is almost certain the timing has gone out.

Best case its a re-time and likely replacement of the 'guides'? £350-£400.

Worst case its damaged valves and its strip down and rebuild time.

He seems to think the N46 engines have a reasonably common issue with their chain guides breaking so once this is sorted, I think she is going up for sale.

These older BMW engines (N42, N46, N47 etc) seem to have far too many chain issues considering what they cost. Don't get me wrong, all cars have known faults but rarely ones which tank the whole engine if they happen.

Your right about the N40/42 having a terrible reliability record and when it comes to to timing chain/tensioner/guide issues its more a case of when not if. On a more positive note the N42 is whats know as "a non interference engine" which basically means the valves and pistons cant come together so at least this shouldn't be a concern. Hopefully a new chain/guides/tensioner etc should put it right.

Hers is an N46, is this still a non interference engine?

Google suggests its not :S

Yes it's basically just a revised n42

[laurieballard]

Hopefully you are all right and it is non interference, at least that way it may not cost as much to repair.

Still awaiting a call from the mechanic.

[laurieballard]

Turns out the top guide had broken and allowed the chain to jump 3 teeth.

New guide and tensioner and she is back to normal.

Fortunately it did no damage to valves etc.

Cheers

[wonkydonkey]

Huge sigh of relief for you then! Happy to hear that