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Discussion Starter #1
Anyone catch honest john on saturday's telegraph?

Up the creek...

My Nissan X-Trail 2.2 diesel is little more than two years old and is already on its third turbo. On the last occasion the intercooler was also replaced. If I keep the car after the manufacturer warranty expires, can I expect some hefty servicing bills?
W.W., via email

# In a different context, another reader explained why diesel turbochargers sometimes fail: "The Exhaust Gas Recirculation valve should open to allow carbon dioxide (which acts as a cooling gas) into the combustion chambers when the engine is under load (more than 30 per cent boost). This allows the combustion chamber temperature to drop and thus the temperature of the exhaust gases. If it sticks in the closed position the exhaust gas temperature will rise, causing the turbo bearings to fail and eventually allowing engine oil into the induction system. This can cause the engine to run on its crankcase oil until it is either stalled or goes bang. Problems with EGR valves are also often the cause of rough running when the valve is stuck in the open position as well. In several cases turbos have blown but the EGR valve has not been replaced. Inevitably the new turbo unit will not last long." The most common cause of the EGR valve sticking is dirty, sludged or otherwise contaminated engine oil.
Honest John's agony column | Honest John | Motoring | Telegraph
 

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it seems to me as if some people could be using the wrong engine oil. i have owned my scenic for around 18 months and the engine has always sounded as if the main bearings were rumbling. i have changed the engine oil twice. the 1st time i used 10w/40 semi synthetic which helped slightly but not a lot. i have recently chainged it again but this time i used a 5w/40 full synthetic oil. WOW what a difference. it sounds like i have changed the engine. this is proof that its essential to use the correct oil to suit the engine. at all cost avoid the cheap crap like the plague. full synthetic can be found from £16 depending on the supplier and the actual oil:d:d:d
 

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Having a petrol you're less susceptible to exploding turbos though :d
i tend to disagree. petrol and diesel engines both have EGR valves and both serve the same purpose. they are not essential to the running of the engine in the way that the engine will not run at all but they are fitted to reduce internal temperatures which in turn reduce emissions. most or all modern diesel engines are fitted with catalytic converters. if these fail they can be removed and fitted with a normal piece of pipe as they are not tested during the mot unlike petrol cars. this has no effect on the way the engine runs although there may be a bit of difference if the car is fitted with a modern electronic controlled system. i removed the cat from a very late pug 405 turbo diesel and the only difference i see is that my wallet never lost weight. all i had to do was replace the cat with a normal non cat front section which cost about £17 compared to around £75 for a new cat. another tip with ANY turbo charged engine is during start up and turn off.
1/ when starting the engine do NOT rev the engine but let it tick over for 30 seconds so the turbo bearings get a got dose of oil
2/ at the end of your journey do NOT switch the engine off straight away but let it tick over for around a minute. this gives the turbo time to come to a halt because if you switch straight off the turbo will continue to spin with no oil supply which will knock out the turbo bearings in no time at all. this will save £500 or more on a new turbocharger
 

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Discussion Starter #6
i tend to disagree. petrol and diesel engines both have EGR valves and both serve the same purpose. they are not essential to the running of the engine in the way that the engine will not run at all but they are fitted to reduce internal temperatures which in turn reduce emissions. most or all modern diesel engines are fitted with catalytic converters. if these fail they can be removed and fitted with a normal piece of pipe as they are not tested during the mot unlike petrol cars. this has no effect on the way the engine runs although there may be a bit of difference if the car is fitted with a modern electronic controlled system. i removed the cat from a very late pug 405 turbo diesel and the only difference i see is that my wallet never lost weight. all i had to do was replace the cat with a normal non cat front section which cost about £17 compared to around £75 for a new cat. another tip with ANY turbo charged engine is during start up and turn off.
1/ when starting the engine do NOT rev the engine but let it tick over for 30 seconds so the turbo bearings get a got dose of oil
2/ at the end of your journey do NOT switch the engine off straight away but let it tick over for around a minute. this gives the turbo time to come to a halt because if you switch straight off the turbo will continue to spin with no oil supply which will knock out the turbo bearings in no time at all. this will save £500 or more on a new turbocharger
Sound advice - and my lag is decatted :d Full stainless but for the exhaust manifold lol
 
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i tend to disagree. petrol and diesel engines both have EGR valves and both serve the same purpose. they are not essential to the running of the engine in the way that the engine will not run at all but they are fitted to reduce internal temperatures which in turn reduce emissions. most or all modern diesel engines are fitted with catalytic converters. if these fail they can be removed and fitted with a normal piece of pipe as they are not tested during the mot unlike petrol cars. this has no effect on the way the engine runs although there may be a bit of difference if the car is fitted with a modern electronic controlled system. i removed the cat from a very late pug 405 turbo diesel and the only difference i see is that my wallet never lost weight. all i had to do was replace the cat with a normal non cat front section which cost about £17 compared to around £75 for a new cat. another tip with ANY turbo charged engine is during start up and turn off.
1/ when starting the engine do NOT rev the engine but let it tick over for 30 seconds so the turbo bearings get a got dose of oil
2/ at the end of your journey do NOT switch the engine off straight away but let it tick over for around a minute. this gives the turbo time to come to a halt because if you switch straight off the turbo will continue to spin with no oil supply which will knock out the turbo bearings in no time at all. this will save £500 or more on a new turbocharger[/QUOTE

The CAT makes little difference to emissions about only3% and not all turbos are halted on tickover but yes its in most handbooks to let engine idle for a short while this to lower temp of turbo after a run not sure how effective that is as most do town driving before stopping so turbo won't be that hot.
 

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The turbo will still be spinning at idle, just much slower, and not producing any significant boost.
 
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