Smoking 406 DT

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Bryans Wagon
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Joined: 02 Aug 2003, 04:07

Smoking 406 DT

Post by Bryans Wagon » 02 Aug 2003, 04:25

Early 1996 406 1.9 DT with air con. Done 120k miles, most journeys being 20 miles on traffic free roads.
Problem is that it emits a large quantity of grey/blue smoke once it has been idling for a couple of minutes and is then driven off, smoke clears within five seconds, there is no smoke at start up or when on the move which seems to discount valve seal wear or injector trouble. Other than this car runs well and does not use any oil.
No work has ever been done on the engine or fuel system other than regular servicing using Peugeot parts, apart from I use oil which is fully synthetic Duckhams or Castol Deisel oil.

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Joined: 21 Dec 2001, 16:19

Smoking 406 DT

Post by mbunting » 02 Aug 2003, 14:28

Well, oil is getting burnt somehow !!
If it's getting into the combustion chamber, it will be burned whatever the conditions, so you'd see smoke all the time ( in various degrees ).
You say 'it doesn't use any oil', well, it obviously does, but aparently in very small amounts.
I would check the air intake system, and I would suspect a turbo oil seal - which is allowing oil through the intake side at idle ( they all do to a very small degree aparently ), and is then being 'blown' through the intake system into the engine when the revs rise.
The best way to check this is to leave the car overnight ( or to get COLD ), and then take the side-pipe off the turbo, and visually check for oil pools in the turbo housing.
Air + oil ? here-> ==O-O <-Exhaust pipe

Dave Burns
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Joined: 14 May 2001, 05:30
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Smoking 406 DT

Post by Dave Burns » 02 Aug 2003, 15:11

Could be turbo oil seal, but on the exhaust side in my opinion.
If the bearings are worn the shaft won't be held 100% concentricly at tickover, this may alow oil to escape from the top edge of the seal.
At higher running speeds the oil pressure will increase and the turbo spin much faster, the hydrodynamics of the oil/bearings will then centre the shaft.
Could be oil control rings, at tickover there will be a partial vacuum and oil could be sucked past, could also be intake valves letting oil run down stem at tickover.
Won't get these symptoms during driving speed running because you will then have boost, partial vacuum gone and replaced by positive pressure.