V12 spits out carbon

[V12Smig]

On start up my V12 always shoots a trail of water squirted out of the exhaust, I always put it down to condensation in the pipes. The water always contains the carbon from the exhaust, this happens all the time on start up, even when warm. Yesterday after a very fast blap back from Southside Hustle, with my friend behind me in his newly painted cobra, he sent me an angry text with a photo of the front of his cobra completely covered in my exhaust carbon..... The whole front end was covered... doh. I would've expected this if I drove moderately slowly, but fitted with a manual gearbox, she always gets the Italian tune up more often then not, mostly on every trip.
Is this something that indicates a problem? Is there something I can do to remove, minimise this?

[PaulGover]

What sort of V12? The EFI versions shouldn't produce carbon unless they've leaks (broken piston rings, failed valve stem oil seals, holed pistons) taking oil into the engine. If it's carburetted, then a bad attack of mistuning is possible, but I'd still suspect some sort of oil leak to produce enough carbon to coat a following car.

[V12Smig]

Hi Paul, its an 85 Sovereign V12. Its got an AJ6 engineering ECU, I have done a lot of work on keeping it cool and she struggles to get to 90 degrees... I don't think its any of the issues you mentioned, there's no smell of oil in the exhaust and the level has barely moved since it was last serviced... certainly no loss of performance or power

[mike020150]

One slightly less worrying possible diagnosis than Paul's could be purely exhaust related. If the car still has its original or very old silencers fitted, their contents (rust and bits of glass fibre packing) could be being fired out under heavy acceleration. It can take a long time for silencers to fully break down on the inside, long before they fail more obviously by leaking exhaust gas. Mike.

[V12Smig]

Hi Mike, thanks for your reply, its got a recent stainless system... The more I think about it the more I think its because she rarely gets to 90 degrees.... Maybe I should put foil on one side of the grill like many did in the 70s!

[V12Smig]

So yesterday, even though it was sunny, the outside temp was around 10 degrees. I ran the car static for 15/20 minutes to get the temp up. The draw of the fan was very noticeable through the grill, so I blocked off the grill to assist in the temp rising, I got it to about 80 degree and all condensation and soot had dispersed. Seems as if the new viscous coupling, plus 3 core rad and other cooling mods has helped keep the temp low, which will be a bonus in the summer. Also having the correct foam around rad obviously makes a massive difference to the amount of air entering the rad and not being lost either side.

[mike020150]

Any cooling improvements along the lines you've indicated shouldn't make the engine run so cool that it over-fuels and produces black smoke/particles. The engine thermostats are there to take care of that. Hence, I would take out the thermostats, ensure they are of the correct type and test them, to ensure they're opening at the temperature stamped on the thermostat body. There are many non genuine thermostats around which don't perform well. Similarly, it would be worth checking the engine temperature sensor (not the temperature gauge sensor) to ensure its readings are correct. These sensors tend to fail 'rich' when they die. Mike.

[V12Smig]

Understood Mike, thank you, will get this look at and post what I find...