E36 4 pot rough idle

[peaktorque]

My old E36 318i (with the crappy M40 engine), starts on the button despite never really moving from my driveway! The problem is that the idle is rough (hot or cold)and there is a bit of white smoke 'out back', the engine is sweet sounding though. The problem is made worse if I remove the oil filler cap, where it nearly stalls and there seems a bit of a positive pressure.
The old girl has had a new head gasket and two new inlet valves (as a result of neglected cambelt change!). It does seem like a head gasket problem to me, but I'm pretty sure it was fitted properly. Just wondering if there are any other potential causes of this, such as an ERG or CCV valve that may be creating these symptoms?

Thanks in advance!

[Gad-Westy]

peaktorque said:

My old E36 318i (with the crappy M40 engine), starts on the button despite never really moving from my driveway! The problem is that the idle is rough (hot or cold)and there is a bit of white smoke 'out back', the engine is sweet sounding though. The problem is made worse if I remove the oil filler cap, where it nearly stalls and there seems a bit of a positive pressure.
The old girl has had a new head gasket and two new inlet valves (as a result of neglected cambelt change!). It does seem like a head gasket problem to me, but I'm pretty sure it was fitted properly. Just wondering if there are any other potential causes of this, such as an ERG or CCV valve that may be creating these symptoms?

Thanks in advance!

Piston rings maybe? Is it losing oil?

Worth getting a compression/leak down test done by the sound of things.

[peaktorque]

Gad-Westy said:

peaktorque said:

My old E36 318i (with the crappy M40 engine), starts on the button despite never really moving from my driveway! The problem is that the idle is rough (hot or cold)and there is a bit of white smoke 'out back', the engine is sweet sounding though. The problem is made worse if I remove the oil filler cap, where it nearly stalls and there seems a bit of a positive pressure.
The old girl has had a new head gasket and two new inlet valves (as a result of neglected cambelt change!). It does seem like a head gasket problem to me, but I'm pretty sure it was fitted properly. Just wondering if there are any other potential causes of this, such as an ERG or CCV valve that may be creating these symptoms?

Thanks in advance!

Piston rings maybe? Is it losing oil?

Worth getting a compression/leak down test done by the sound of things.

Thanks for the reply, not sure about the rings as I would expect blue smoke rather than white. I must admit that when the head was off there is no evidence of wear in the cylinders at all. I won't rule it yet though! As for oil use tbh I never drive it so I can't say! Can't find my bloody compression tester either !

[Gad-Westy]

peaktorque said:

Gad-Westy said:

peaktorque said:

My old E36 318i (with the crappy M40 engine), starts on the button despite never really moving from my driveway! The problem is that the idle is rough (hot or cold)and there is a bit of white smoke 'out back', the engine is sweet sounding though. The problem is made worse if I remove the oil filler cap, where it nearly stalls and there seems a bit of a positive pressure.
The old girl has had a new head gasket and two new inlet valves (as a result of neglected cambelt change!). It does seem like a head gasket problem to me, but I'm pretty sure it was fitted properly. Just wondering if there are any other potential causes of this, such as an ERG or CCV valve that may be creating these symptoms?

Thanks in advance!

Piston rings maybe? Is it losing oil?

Worth getting a compression/leak down test done by the sound of things.

Thanks for the reply, not sure about the rings as I would expect blue smoke rather than white. I must admit that when the head was off there is no evidence of wear in the cylinders at all. I won't rule it yet though! As for oil use tbh I never drive it so I can't say! Can't find my bloody compression tester either !

A local garage should be able to do a comp test if you bung them a tenner. Its funny, I've often heard of the blue smoke thing but I've had two cars where oil was leaking into the cylinders, one through the rings, another a valve stem and they both showed white smoke. That said, how is your water looking? Temperature steady? Just seems odd that removing the oil cap is making things worse.

[David87M3]

are there any split vacuum pipes anywere? Idle control valve may need cleaning. Intake gaskets?
Is the dizzy cap and rotor ok?

[peaktorque]

David87M3 said:

are there any split vacuum pipes anywere? Idle control valve may need cleaning. Intake gaskets?
Is the dizzy cap and rotor ok?

Need to spend some time having a good look at it really! Dizzy cap and rotor are new!

[m3pilot]

Something you can check easily is the inlet manifold gaskets and the intake hoses. Spray WD40 around the gaskets if the car starts to idle faster you've got a leak.

[peaktorque]

m3pilot said:

Something you can check easily is the inlet manifold gaskets and the intake hoses. Spray WD40 around the gaskets if the car starts to idle faster you've got a leak.

Thats an idea , thanks!