Major smoke on startup: blown head gasket????

dickstar1977 · 7 Mar 2017

Morning all

So, took my car (996, c2, 62K, recent major service, coil pack , also new clutch and bearing and AOS last august) for a run from Nottingham to Boston last night, she drove like a peach (normally just trundles round town).

Got in the car for the school run this morning and on start up cloud of white smoke out of the exhaust (smelt like fuel not oil and with a back breeze had disepated by the windscreen). Got out and got my son to press the accelerator and ever 'fuel smelling' smoke from both pipes but much lighter more like normal cold morning start up. (It's not a car that smokes ever on start up other than the usual cold weather vapour smoke)

Turned it off, check the error messages nothing! Checked the oil and coolant and no sign of intermix. Walked son to school and then went home and started it again, no smoke, drove it to my mechanic 5 mins drive away a small amount of 'cold running vapour smoke but quickly cleared and no more smoke, warmed up fine, temp and pressure fine!

Got to my mechanic, heavy throttle and nothing, ran fine!

Any thoughts or advice? Never happened before and was an excessive amount of 'fuel smelling' white smoke on start up but then ran fine

Please help, at mechanics now

pzero · 7 Mar 2017

Oil overfill when serviced :dont know:

dickstar1977 · 7 Mar 2017

Nope, serviced about two months ago and has run absolutely fine since

It did get quite a hard drive in cold wet conditions last night and I didn't let it idle before shut off, I've read on google that this might be the cause but it's never happened before in 6 years of ownership

Could it be a head gasket problem?

wiggy · 7 Mar 2017

My air oil separator went and behaved exactly as you have described. It was a £700 engine out job on my C4. I think a C2 can be done with the engine in.

Have a look at this old youtube vid.

https://www.youtube.com/watch?v=FKmjatZmUo0

Wig

dickstar1977 · 7 Mar 2017

Wig

Only reason I didn't think AOS is that it was done last august at Zentrum in Nottingham and the smoke didn't continue, when it happened last time it was continuous??

More worried the head gaskets gone but done know enough to know. Did check the coolant and no oil and checked the dip stick and no intermix????

wiggy · 7 Mar 2017

dickstar1977 said:
Wig

Only reason I didn't think AOS is that it was done last august at Zentrum in Nottingham and the smoke didn't continue, when it happened last time it was continuous??

More worried the head gaskets gone but done know enough to know. Did check the coolant and no oil and checked the dip stick and no intermix????

When mine went it only smoked at startup. It was worse if I only moved it a few feet the startup before, like just pulling it out the garage then leaving it a day then starting it smoked like crazy.

dickstar1977 · 7 Mar 2017

Still not heard from the garage, are there any thoughts on if it could be the Head Gasket?

Also has anyone known of an AOS failure within a year of it being fitted?

Windy101 · 7 Mar 2017

pzero said:
Oil overfill when serviced :dont know:

What was the oil level showing as. Its worth looking into this option.

Robertb · 7 Mar 2017

dickstar1977 said:
Still not heard from the garage, are there any thoughts on if it could be the Head Gasket?

Also has anyone known of an AOS failure within a year of it being fitted?

Not inconceivable that it could have been a dodgy AOS unit. Bad luck though, albeit a better option than other potential faults.

AOS failure will also mean considerably higher oil consumption.

When mine went I had no smoke, but a dreadful screeching noise.

In your case, maybe it was 'one of those things'. If no faults logged, no oil where it shouldn't be then I'd keep a watching brief.

Halcyon · 7 Mar 2017

don't they all do this occasionally?

The exhaust valve sometimes stops in the open position and a bit of oil seeps into the cylinder (a teeny bit of oil can cause quite an impressive plume!)
it'll give a bit of a belch as it clears and carries on as normal.

If you have no other symptoms, no errors, no contaminated coolant, no excessive oil use and it doesn't do it again (for a while at least) then move along, nothing to see here! :thumb:

Stoo.c · 7 Mar 2017

Incredibly unlikely to be a head gasket. Due to the configuration of the engine its no uncommon for a bit of oil to run into the cylinder as already mentioned and then burn off when you next start it.

moorhouse · 7 Mar 2017

Are you sure it was actually smoke and not just heavier than normal dose of vapour/steam. Depending on relative temp/humidity mine sometimes throws out loads - assume that water in the exhausts condenses more on some occasions than others, again I notice it more when the air is damp/cold. If the clouds clear quickly in the air then I reckon its vapour as proper smoke tends to hang around a bit more. You seemed to suggest it was dissipating pretty quickly. When it happens though its always a bit alarming. Think the fuel smell is normal just at startup as it runs rich.

Just my thoughts.
Cheers.....Ian

Marky911 · 7 Mar 2017

As above. Are you sure it's not just the boxer engine puff??

Very common. I mean common in that loads of cars do it but not every start.

Rare for an AOS to fail so soon after fitting so I wouldn't be looking there yet.

mzmini · 7 Mar 2017

My money is on the boxer puff both mine have done it used to worry the crap out of me , now I accept that its a Porsche thing :lol:

dickstar1977 · 7 Mar 2017

Thanks chaps

So, still nothing from my mechanic, he's Porsche specialist but old school (often the best)

So, from recollection, turn key... check oil...... start, cloud of white smoke/ vapour

I immediately looked round and got out the car, by the time I exited the car it was dissipating. It was more like the vapour smoke on cold running but a considerable amount (never done it before)

Turned off and did checks as previsouly mentioned, restarted and basically started as a normal cold run, a small amount of vapour smoke but nothing more. Drove to my mechanic and again no noticeable smoke and when I got there it had half warmed up and pressure dropped to 3 bar on the oil pressure, no smoke or even vapour

God knows.............. its been an anxious day!

Hopefully more news tomorrow

Thanks for all the input

Major smoke on startup: blown head gasket????

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