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Exhaust Smoke on start up
kombikim - February 6th, 2003 at 07:47 AM

our rebuilt 2L now has about 2500k on it
but when I start up cold in the morning there is still the short lived cloud of blue smoke,
the quantity generally related to how long it takes to start MY QUESTION IS-- because of the flat configuration of the motor & the fact that we have quite a bit of camber on the road where we park, does oil sit down the left hand cylinder bank & cause this?:o


aussiebug - February 6th, 2003 at 10:21 AM

It's quite common to get a short period of smoke on startup with the flat engine design, since the cylinders are horizontal and so oil can pool on the bottom side of the cylinders. If the vehicle is parked on a slope sideways this effect would be even more pronounced for the downhill cylinders - you'd get some oil pooling behind the pistons and might get a few drops seeping past the pistons into the head area.

I would have thought that 2500km would be enough to bed the rings etc in and reduce the smoke to a minimum, but maybe the rings are still settling.

I presume you are using a suitable oil too - a 10w30 would be OK for the winter but a little thin for the Aussie summer months...a 20w50 would be better (can be used all year round in Aus except for areas which have constant sub-zero temps in winter.


kombikim - February 6th, 2003 at 10:56 AM

Thanks, Rob,
that was my theory, but I thought I had better check, assumptions are quite often wrong, what are your views on the thermostat, my view is that it should be fitted, but when car came back with new engine it were not there & the Guy said you don't need it in Aust.
I do use the 20/50 Penzoil


Baja Wes - February 6th, 2003 at 12:40 PM

Yes parking on a cambered road / side slope will cause the oil to seep past the pistons and blow black smoke at start up. I parked my baja on a side sloped driveway for a year and it always smoked.

I think that is why subaru went to such a deep sump design, to get the oil level well below the cylinder and prevent the problem from happening.

If I was in sydney I would fit the thermostat.


geodon - February 6th, 2003 at 05:46 PM

I always make a point of making sure no ring gaps face downwards to minimise the oil seepage.


SKEWtYpe3 - February 6th, 2003 at 11:51 PM

i stopped parking on the slope side because of that
actually i stopped parking on the slope 'cos my mum was telling me to get it tuned all the time !!!!!!!!!!!!!
:bounce


Andy - February 7th, 2003 at 12:23 AM

It's also the same on my BMW bike (air cooled flat twin). If I park it on the side stand, the left cylinder will smoke at startup.
Oh, I don't think the depth of the sump has much to do with it. The BM sump level is low enough to not fill the back of the cylinders. It's just oil drips pooling from the back of the cylinder.
Just make sure it is a blueish smoke and smells like burnt oil, not petrol, otherwise it could be another problem.:thumb


kombikim - February 7th, 2003 at 07:35 AM

yep it is definatley blue smoke
Re checking the ring gaps are not at the bottom, I think I will leave that job untill four or five years time!!
Kim


geodon - February 8th, 2003 at 05:24 AM

Kombikim the post was but a hint for future work. You would need to be a maximum anally retentive environmentalist to rip into a motor & turn the gaps around in the slight hope of fixing a minor problem like this!!


Baja Wes - February 9th, 2003 at 01:02 PM

plus you'd have to use new rings, because the current ones would be bedded in to the orientation they are at now.

I don't think ring end gap orientation would make much difference anyway. I never put my ring gaps at the bottom, but my engines still blew smoke after parking on side slopes.


kombikim - February 9th, 2003 at 09:23 PM

I am not really Annually retentive I just have a sad sense of humour. In the future I just want an engine like Amazer's - he is my hero & a Q-ship is a lot of fun.