What colour is the smoke, blue, black or white ?
My initial thought would be the turbo, especially if it's been changed
recently.
Or the oil drain from it being blocked.
Jim
On 10/06/2012 19:07, Susan and Martin Scott wrote:
As the plugs are clean should the valve stem seals be suspect?
Could it be getting through the turbo into the exhaust? Could it be
that it is actually smoking on boost but not as visible?
Just some thoughts...
----- Original Message ----- From: "barnacle" <[email protected]>
To: "Quantum Owners Group" <[email protected]>
Sent: Sunday, June 10, 2012 6:00 PM
Subject: [Quantum Owners] Fiat 20vt quantum smoke issue...
Scratching my head on this one... couple of weeks ago the 20vt 2+2
passed its MOT after a lot of work rebuilding the brake and clutch
master cylinders, dropping in a new turbo, and rebuilding the inlet
ducting.
Two hundred miles later it started smoking. Not a mild 'just a couple
a day' but a full sixty a day habit, the sort that makes passing
policemen raise an inquisitive eyebrow and makes people wait thirty
meters behind you at the lights.
It smokes on idle. It smokes on overrun. It smokes on gentle running.
It *doesn't* smoke on boost except momentarily at the start of boost.
Today I have (with the very welcome assistance of Joe, who's an expert
on these engines):
- pulled the inlet plumbing from the turbo: clean
- pulled the exhaust plumbing from the turbo: clean
- checked the turbo shaft for bearing wear/movement: nothing
- checked the turbo actually turns: yup
- checked the lambda sensor: clean
- replaced the positive crankcase ventilation valve with a block (it
was leaking *slightly*)
- tested for pressure from the oil filler: none
- checked the oil for water and the water for oil: none
- checked all five sparkplugs: clean
- checked the compression (cold/dry) on all five cylinders: 150psi +/-
5psi = well within spec
- cursed the engine quite comprehensively, including the sacrifice of
a chicken or two
There is absolutely no evidence of oil being burnt in the engine apart
from the fact that it's a mobile smokescreen...
The next thing is to drop a new head on it. All we can think of now is
the valve stem seals (cracked piston, rings, or valves seem excluded
by the pressure readings) and this is not a fault for which this
engine is renowned - I know of perhaps three cases in fifteen years.
What have we forgotten? Any other thoughts?
Ta,
Neil
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