[raptor_f22]

Hi all,

Just picked up my used 740d yesterday - posting on the 5 forum as it seems to be more active and people keep saying that the cars are quite similar.

Basically, whilst driving everything working just fine until I turned the air con on. Cold air coming out no problem, no issues, just a slight moaning noise when air con running if you listened hard enough (good sound insulation?).

Suddenly get burning smell coming through vents, pulled the car up and smoke pouring from engine bay. Seemed to be coming from back of the engine block either in the middle or passenger side. Initially I put it down to the water from the condensor dripping onto something hot and oily but that can't be it.

Engine off, air con turned off, waited for smoke to go.

Got back in the car, turned air con on, same thing happened. This time after switching the air con off and waiting for the smoke to go away, everything was fine afterwards . i.e. whatever the issue is, only happens when the A/C is turned on.

Hard to see behind the engine block but I did spot that there seems to be an oil leak of some kind. Tried to shoot a video but couldn't get the phone camera to pinpoint to where I can see the greasy bits - basically back of the engine block on the drivers side. Past experience with my E92 330d says that can be caused by blocked crankcase breather

I noticed this morning that the undertray was soaking wet too and now the battery doesn't seem to be holding its charge very well. It's like the air con has just pissed fluid everywhere

I looked in the service history and it's spooky that this issue has happened before (seller discussed it with me) and the BMW specialist sorted it out. Reading their description on the invoice, it seems like the exact same thing again perhaps?

Not sure what could have gone wrong but safe to say i'm not touching the air con for a while. Any advice guys?

[robbiep]

Advice : reject car under Consumer Rights Act for a FULL refund. You have 30 days in which to do so.
You can CHOOSE to accept an attempt at repair, but it is YOUR choice, NOT the garage's choice.
Note that after 30 days, your rights start to diminish. Use them or lose them !

[raptor_f22]

Originally Posted by robbiep

Advice : reject car under Consumer Rights Act for a FULL refund. You have 30 days in which to do so.
You can CHOOSE to accept an attempt at repair, but it is YOUR choice, NOT the garage's choice.
Note that after 30 days, your rights start to diminish. Use them or lose them !

Its used private not from BMW

[raptor_f22]

Update: I suspect it isn't evaporator temp sensor that's faulty as the air con specialist diagnosed last week.

The wet undertray is actually oil so I suspect oil leaked onto a hot part when the air con was operating (possibly the compressor?) causing the smoke.

At the top left rear of the engine block there's a part which is covered in oil. I think it's the culprit but I can't seem to narrow down what part that is - crankcase breather?