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Matt, Mechanical Engineer
Category: UK Car
Satisfied Customers: 21103
Experience:  BEng hons Mech engineering, in auto industry 22 years
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my laguna 2 1.9 dci has recently started smoking heavily without

Customer Question

my laguna 2 1.9 dci has recently started smoking heavily without any apparent reason.the car runs well and uses no oil between services. no mechanical noises or leaks.
a friend of mine had similar problem but was corrected in minutes by a local mechanic.
unfortunately both are on holiday at this time.
Submitted: 6 years ago.
Category: UK Car
Expert:  Matt replied 6 years ago.

what colour is the smoke?

Also how many miles are on the car?
Customer: replied 6 years ago.
colour of smoke is light blue rather than a dark blue normally associated with oil burning.tried running engine at idling speed minus turbo feed to manifold. . a qualified mechanic looked at it on sunday and says there is very little back pressure at oil filler tube so doesnt think any undue blow bye at pistons. engine sounds healthy and minus unusual noises. a friend of mine with same car and same engine had similar problem but it was traced to leak in intercooler.
my other worry was that it could be contaminated fuel.
car has done 130.000 but with regular servicing and filters changed.
any ideas buddy.
am at wits end and will be going to southampton shortly
i was a mechanic years ago so have good knowledge of car engines
thanks for any help
Expert:  Matt replied 6 years ago.

If you're getting a light blue / grayish smoke then it could be and issue with the Injection timing or fuel is not being atomised correctly or as you say something other than diesel has been added to the the fuel tank.

to check injection timing aspect - inspect the cam position sensor for any wiring damage or corroded connections - if in doubt replace the sensor

Also worth trying a bottle of injector cleaner to hopefully improve combustion

and if there's water / petrol in the diesel best off topping up with fresh diesel to dilute whatever is in the tank and consider replacing the filter
Customer: replied 6 years ago.
thanks for that but i am not entirely convinced. the car starts and runs well with no loss of performance. smooth and quiet as always. no miss-fires or uneven idling. swiss watch.
i foned my friend who had similar problem with his car and he confirmed it was intercooler. not being mechanically minded he cant be more specific until he contacts the guy who repaired it.
be in touch
Expert:  Matt replied 6 years ago.
Hello Joe

I can't quite see how a faulty intercooler would introduce oil / fuel to the mix to produce the smoke.

If you had a leak in the intercooler you should be able to find it with soapy water as it'll produce bubbles with the engine running. if it was leaking you may feel slightly down on power and possibly hear a 'hissing' noise with the bonnet up
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Customer: replied 6 years ago.
dont fathom that out myself but that is what he said. still none the wiser. cant fix what aint broke as they say. cant order new bits cos i dont know what dont work. mystery.
i have accepted your answer so you should get your money.
if ( when) i get to the bottom of things i will drop you a note for future reference. think i am going to have to resort to renault dealer. thanks anyway.
be in touch
Customer: replied 6 years ago.
problem with laguna 2 dci 1.9 has been traced to the turbo bearings leaking oil causing. a replacement turbo and egr valve were fitted.
car runs like a dream despite 130.000 miles.