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I have a VW Golf mk4, 1.9 TDI from 2001 with 230.000+ km on board and for some time now I have blue smoke coming out of the exhaust.

The problem aggravates when I'm stuck in traffic or when the engine is kept at low revs for a long time. After that, when I rev it up, tons of smoke come out, then it goes back to just little puffs of smoke, visible only if you get in the back of the car.

I eats about 750ml of oil every oil change cycle.

For now I have 2 suspicions: oil getting in the turbo and oil getting in the burning chamber, but both cost a lot and there is nocheap "let's see which is wrong" ...

What do you guys think, and how long do you think I can keep running like this ?

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3 Answers

up vote 4 down vote accepted

Have a look at your owners manual if it states a maximum oil consumption. I don't think that 750ml over a whole oil change interval is a lot.

My guess would be that it's more likely an issue with the turbo and investigating if it is shouldn't be that expensive. Essentially you or your mechanic would need to pull the pipes going from the turbo to the intake and check for both play in the turbo shaft and oil accumulation in the intake piping.

As to how long you can drive around like this, well, keep in mind that if the turbo has axial or radial play, the turbine wheels will eventually contact the housing and either shave metal off the housing or blades. In general, engines don't like ingesting metal so you can turn an expensive but straightforward repair into a partial engine rebuild if you wait too long.

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As a reference point, the manuals for both my cars permit oil consumption up to 1 quart (~946ml) every 1000 miles. While annoying, I wouldn't be concerned if it was truly the engine eating that much since it would most likely just be wear that isn't going to result in catastrophic failure. I'm much more concerned about the turbo though. You do NOT want oil sneaking past the turbo oil seals. Usually indicative of a coming major turbo failure, which as Timo mentioned, can take the whole engine with it. –  Brian Knoblauch Dec 19 '11 at 16:34
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Golf TDis (and I'd imagine other VWs of that era) are notorious for the Turbos failing. It can be a very expensive fix once it goes properly, so I'd get it investigated asap.

From your description, I'd surmise that oil is seeping through one of the seals into the turbo, then when you rev the engine and the turbo spools up, the oil that has accumulated at idle is blown through, hence the big cloud.

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It might be your Mass Air Flow (MAF) sensor. mine has been replaced 3-4 times over 230K miles. this is the typical symptom. another symptom can be loss of power. both because the engine is operating poorly because it doesn't know how much air is coming in.

http://www.evolutionimport.com/OEM_TDI_Mass_Air_Flow_Sensor_For_A4_TDI_p/038%20906%20461c.htm http://www.myturbodiesel.com/1000q/multi/maf-faq-tdi.htm

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A partial/total failure of the MAF sensor wouldn't result in some fault codes in the car diagnostics ? –  Nicolae Surdu Jun 26 '13 at 20:05
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