why is my engine smoking

[tommype30cab]

hi, ok i posted a thread on here a while ago about my 2.7 m30 that smokes when revved (sp) hard. it was kind of decided that it could be the piston rings. recently ive changed the head gasket and all the bores look perfect, a mechanic has backed up my view on them.

by the way the engine is made up of 525e eta bottom end and standard 325i head

the car has a superchipped ecu, but it is only a 2.5 ecu as far as i know and when i go to start the car on occasions it seems like the battery is flat, the engine wont turn fast enough to start the car, the battery is fine and so are all the earths and connections so could the timing be out?? if so could this cause a puff of light grey smoke when the clutch is lifted back up? there is a strange clicking at the same time, it sounds a bit like the noise a cigarette lighter makes when the wheel turns (sorry for the rubbish discription) and the ignition pinks a but when you accellerate hard. can anybody shed any light on this cos i want to sell the car fairly soon but refuse to sell it with a dodgey engine lol, thanks in advance everyone

Tom

[stonesie]

hi, ok i posted a thread on here a while ago about my 2.7 m30 that smokes when revved (sp) hard. it was kind of decided that it could be the piston rings. recently ive changed the head gasket and all the bores look perfect, a mechanic has backed up my view on them.

You can only tell if the bore is excessivly worn by looking at it, to tell if the rings are worn you need the pistons out, remove the rings and put them back in the bore, then measure the gap with feeler gauges and compare that to the manufacturers specification.

by the way the engine is made up of 525e eta bottom end and standard 325i head

the car has a superchipped ecu, but it is only a 2.5 ecu as far as i know and when i go to start the car on occasions it seems like the battery is flat, the engine wont turn fast enough to start the car, the battery is fine and so are all the earths and connections so could the timing be out??

If so, could this cause a puff of light grey smoke when the clutch is lifted back up?
There is a strange clicking at the same time, it sounds a bit like the noise a cigarette lighter makes when the wheel turns (sorry for the rubbish discription)

The puff of smoke is most likely to be oil coming past the rings or valve stem seals when the throttle is closed on a gearchange, that creates a high vaccume in the cylinders.

The click type noise (assumeing that you mean turning the steering wheel) could well be a broken coil spring.

The ignition pinks a but when you accellerate hard. can anybody shed any light on this cos i want to sell the car fairly soon but refuse to sell it with a dodgey engine lol, thanks in advance everyone

Tom

That sounds like the ignition timeing is too far advanced or the mixture too lean.


hope at least some of that helps

Matt

[tommype30cab]

thaks matt, weve done a bit of investigation tonight, the smoke is grey and not blue, indicating its probably not oil (i think). The chicking happens whenever i bring the clutch up quickly, sorry i shouldve made that clearer

the pinking, clicking and smoking makes me wonder if:

a the timing is out
b i need a different ecu, one desighed specificlly for the 2.7 engine

thanks for the advice mate, much appreciated

Tom

[Ant]

2.7's need timing to suit.

use a 2.7 chip in the 325i ECU dude !

I can supply these for you if you wanted, no sales pitch here though OK

[tommype30cab]

no problems ant, do you remember we spoke ages ago about this? we thought it was the piston rings at the time, it hasnt got any worse through use though...

how much are the chips? are they exchange? cheers mate