Occasional Puff of Blue Smoke on Startup

[FatFrank]

Hi,
I'm hoping that someone can give me some insight as to whether an occasional puff of blue smoke on startup is normal or not. More often than not everything is fine, but probably 3 times in this summer (I usually drive it a couple of days a week) my 20K 09 DB9 has given a noticeable (visible from the rear view mirrors) blueish puff upon startup that quickly disperses and is, as far as I know, never visible during driving. I'm not sure of the exact conditions every time this has happened, but when it has happened I believe it has always been when I first start up the car in morning. It hadn't happened for probably the last 6 weeks then this morning I started the car, reversed it out of the garage and parked it on the driveway without any sign of smoke. A couple of hours later I went to move it back into the garage, and as I started it a nice sized puff was visible for 2-3 seconds until it dispersed.

I did check the oil level today and noticed that the reading on the dipstick was approx 5 or 6mm above max - it must have been like this since the last service as I have never topped the oil up. I Wanted to mention this as I know with some engines any overfill an cause issues.

It doesn't really trouble me too much, but if it is a sign that something is worn/wearing outside of normal range then I would like to get it fixed before my warranty expires at the end of this year.

Many thanks, FF

[m0isty]

I would get that extra oil drained off and see how it behaves, it's called maximum for a reason!

[Nitro76]

Hi Frank,

This was happening to my 05 DB9 as well. It was diagnosed as faulty PCV Valves on the breather pipes. Recently had the PCV Valves and breather pipes replaced during my last service at Bamford Rose. Have not noticed a re-occurence so far, but it was quite a random issue to begin with. 6 weeks and so far so good.

[Nitro76]

m0isty said:

I would get that extra oil drained off and see how it behaves, it's called maximum for a reason!

I would get this checked too.. I know that on the earlier cars the dipstick was too long, leading to some cases of oil starvation during spirited cornering (Probably when tracking the car) as there was less oil in the sump. This was resolved later by replacing the dipsticks with shorter versions.

I also noticed that mine was filled above the max line, during my last three services.

[Grant3]

The thin oil specified for the V12 (0W-40 like Mobil 1) does cause the occasional puff of oil on start up, but it isn't a DB9 trait, unlike the 911's flat 6 which uses a similar spec of oil and is renowned for oil smoke on startup. If it becomes regular get it checked, the level does sound to be a tad over full if it is 6mm above max, although I'm sure it's fine best double check with your dealer on both counts.
Edited to add... It is also worth posting in The Bamford Rose sticky above

Edited by Grant3 on Sunday 2nd September 22:32

[BingoBob]

Are you sure it's blue and not grey? It's not unusual to get unburned fuel in the cylinder if you start the engine shortly after running it and it didn't have a chance to warm up.

[Quietlybonkers]

Cannot be specific, as I don't have an Asston, but in other cars I have owned that were overfilled and had V engines or canted over ones, oil crept down the valve guides and slipped past the seals, giving the effect as described by the OP. Greatly improved by lowering the oil level, and/or using better oil with a higher viscosity.

[ds2000]

As said previously PCV valves on all cars can often lead to this. My old Supra had the same issue.

[3200gt]

Easy to check if the PCV valves is knackered on a DB9. Usually its the near side one that goes. If you have oil residue gathering in the bottom of the near side throttle body then its highly likely the PCV valve is on its way out. Just unclip the the air intake tube at the throttle body and have a look.
The easy no cost fix used by the guys that race DBR9's is to add a dump tank for the oil and route the two oil breather pipes on the near side throttle body into it. Its only oil vapour that comes out of these and in minute quantities so no trouble. Then cap off the inlets into the throttle body.
But first get the oil level to the correct maximum as excess oil will exagerate the issue.

[FatFrank]

BingoBob said:

Are you sure it's blue and not grey? It's not unusual to get unburned fuel in the cylinder if you start the engine shortly after running it and it didn't have a chance to warm up.

Hi Bob,
I suppose it might not have been full on oil-blue, but it is pretty hard to tell to from the drivers seat. I will have the teenager film a view of my start-ups to see if he can catch it on video. If so, I'll post it.

Thanks to everyone else that replied. All your great comments and advice convinced me that it's worth booking it in at the Dealeship for them to check it over. I just sent them an email to book the car in. Perhaps I'll be able to kill two birds with one stone as they invited me in to look at the Vanquish next week.

Thanks again, FF

[Quietlybonkers]

Final PS. I have always believed that too much oil in the engine was positively risky, as the excess oil pressure could damage the engine. I was told never to overfill - my last Merc flashed a red warning if it thought there was even an egg cup too much. Good luck!

[FatFrank]

Quietlybonkers said:

Final PS. I have always believed that too much oil in the engine was positively risky, as the excess oil pressure could damage the engine. I was told never to overfill - my last Merc flashed a red warning if it thought there was even an egg cup too much. Good luck!

Hi Bonkers,
Good point, Thanks for the reminder. I will definitely mention that to the Dealer when my car goes in. Especially as I'm guessing that at the time of service the overfill was probably more than it's showing now - seeing as the service was done back in the Spring.

[BingoBob]

Oil overfilling is bad in a car with a normal sump. Not sure how it affects a car with dry sump. I suspect it's much less of an issue.

[FatFrank]

BingoBob said:

Are you sure it's blue and not grey? It's not unusual to get unburned fuel in the cylinder if you start the engine shortly after running it and it didn't have a chance to warm up.

Okay, I got the video camera out and let the teen start the car (eeeek!) Any way it wont do this when it's hot or when you first start it up when it's cold............but if I start it in the morning reverse it out of the garage, let it sit for an hour then start it again here is what I get:

First attempt: puff from both pipes;

http://www.youtube.com/watch?v=f-rt09fgqco&fea...

Second attempt, a couple of hours later, heavier puff from one pipe;

http://www.youtube.com/watch?v=qORF78nV9OI&fea...




Any ideas or opinions welcome

[brakedwell]

Looks like residual fuel being burnt off. The automatic choke would have been pumping a lot of gas into the engine as you backed out of the garage, but I don't understand why the smoke is only coming out of one exhaust pipe on the second start. Having said that, my wife did notice more exhaust steam coming out of one pipe as I drove up the drive on a cold, damp morning not long after I got the car two years ago.

[marceltay]

FatFrank said:

Okay, I got the video camera out and let the teen start the car (eeeek!) Any way it wont do this when it's hot or when you first start it up when it's cold............but if I start it in the morning reverse it out of the garage, let it sit for an hour then start it again here is what I get:

First attempt: puff from both pipes;

http://www.youtube.com/watch?v=f-rt09fgqco&fea...

Second attempt, a couple of hours later, heavier puff from one pipe;

http://www.youtube.com/watch?v=qORF78nV9OI&fea...




Any ideas or opinions welcome

Hi Frank,

This is exactly the issue I had and the characteristics were the same. Had BR replace the PCV Valves, and have not had a re occurrence since..

[Murph7355]

BingoBob said:

Oil overfilling is bad in a car with a normal sump. Not sure how it affects a car with dry sump. I suspect it's much less of an issue.

I think it's still not wise (the dry sump is just a different place to store the oil).

I think most engines have a pressure relief valve to allow for relatively slight variations. But overfilling is not a good idea.

[Gibberish]

FatFrank said:

.....Any way it wont do this when it's hot or when you first start it up when it's cold............but if I start it in the morning reverse it out of the garage, let it sit for an hour then start it again here is what I get..

On cold starting, do you touch the accelerator/gas pedal before firing?

Because occasionally, when I first had my car, if I did, it would smoke on start up.

Also if I move it from cold, letting it just run for less than about a minute, then on restarting, there was a chance it would smoke.

So now, if I have to move it, I always allow it to settle down before turning off and I never get any smoke.

[BingoBob]

I think that looks like oil burning smoke.

The PCV system check would be a good place to start, I think.

[michael gould]

nice car Fat Frank........ totaly crap number plate........are you a teenager