About a month ago the turbo blew on my mk5 Golf replaced it and cleaned all the pipes. Since this the car is lacking boost below turbo and the black smoke is so bad I can't see the car behind me. I have deleted the egr removed the cat just a straight through exhaust. No faults is showing up for anything and I have had it tested for boost leaks. Is this a boost sensor or has it bent valves when turbo blew? Mechanic can't seem to get the problem sorted. Anyone have any advice what this could be? It's a 105bhp 2005 pd engine 1.9

1 Answer 1


Your Golf's turbo has a solenoid operated control to vary its geometry. I remember it as part N75. If this is in any way faulty you will have most of the symptoms you are describing.

A hand-held vacuum pump to the turbo's vacuum supply hose will allow you to see the turbo vanes operating correctly. Follow the vacuum hose from the turbo back to the solenoid to find the solenoid. (Taking out the EGR valve will increase your NOX emissions and is not a good, or legal, idea. The straight through exhaust doesn't count a lot either way apart from a possible increase in noise.)

The colour of the smoke is important. Black is not enough air or too much fuel. If the smoke is more blue then black, it means that oil is being burnt. When the turbo goes on an engine it is normal for the exhaust to 'fill' with oil. Your smoke may be due to a lot of this, and the other symptoms could be accounted for by heavy oil saturation of the catalyst convertor and exhaust system choking off the engine.

A last consideration is the replacement turbo you have used. A same size - new - direct replacement should be OK but one from a junk yard or likewise would raise questions on its viability as a replacement. Cleaning the turbo's pipes, hoses, and inter-cooler should be done professionally. Swilling the turbo systems with a degreasing fluid on its own can release a lot of sludge will only go to cause further blockages or problems.

  • Had the turbo checked sayed that it is all working correctly. He sayed it could b bent valves is this possible? The car has no boost under 2009rpm but after that it feels more power than it should b. I think it could b down to a boost sensor would that be possible? And it's really black smoke no blue all.
    – Thomas
    Sep 22, 2014 at 15:43
  • Yes, it could very well have a couple or more bent valves. It is rare for a blown turbo to bend the valves, but if a couple of lumps of the turbo has got into the cylinders, then they may have bent the valves. Sep 22, 2014 at 20:12
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    Yea when the turbo blew it shaved off all the blades. When it blew my cr just stoped as if it stalled. I didn't no it had blowen so I tried to start the car by jump starting it. It's more like bent valves rather than boost sensors of something?
    – Thomas
    Sep 22, 2014 at 23:13
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    Sheared blades on the turbo would not pass through the intercooler to reach the engine, they are just too big. Has any other work been done recently, especially timing belts. Sep 23, 2014 at 18:11

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