Being a first time owner of a turbo engined car I hear some conflicting stories about how long to leave engine idling after a run.
The BX TZD handbook says leave it to idle for "a few seconds" before switching off. How long is a few seconds - 5,10 20 or 60 seconds?
Another web site I read said that it was less important on a diesel turbo as the turbos and exhausts run cooler than on a petrol engine.
I don't want to damage my turbo or engine so have been playing it safe and leaving it about 1 - 2 minutes depending on how hard I have been driving prior to stopping. Sitting waiting is a pain sometimes so if I can safely stop it after say 10 - 15 seconds I will.
I am using top quality oil and intend to change it regularly - about every 7500 km's.
Any advice will be appreciated.
Idling Engine for Turbo Cooling
Moderator: RichardW
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ScottFromNZ
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philhoward
The idling time is two fold; to let the turbo slow down to its idle speed so that it isn't still spinning when the oil pressure dies off when you turn it off, and also to let any excessive heat dissipate from the turbo so it doesn't cook inside a stinking hot turbo and turn to tar!
It is more important in a petrol turbo, as you say, due to the hotter temperatures in petrols. More important is that you don't cane it for the last half mile or so, so there isn't a roasted turbo by the time you come to a halt.
Drive gently for the last few hundred yards and then just let it idle for say 10 seconds I would say is fine..normally as much time as it would take to turn off the stereo, turn off the wipers, lights, shut the windows, pull the handbrake on, etc...
It is more important in a petrol turbo, as you say, due to the hotter temperatures in petrols. More important is that you don't cane it for the last half mile or so, so there isn't a roasted turbo by the time you come to a halt.
Drive gently for the last few hundred yards and then just let it idle for say 10 seconds I would say is fine..normally as much time as it would take to turn off the stereo, turn off the wipers, lights, shut the windows, pull the handbrake on, etc...
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RichardW
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Scott,
Yes diesel turbos run much cooler than petrol ones, so letting it cool down is much less important. If you've really been booting it (eg screaming up mountain passes on full boost) then it would be wise to let it idle for 30 - 60s before switch off. In normal driving, even if you come off the motorway into a service area, just letting the engine return to idle and waiting a few seconds will be OK (as long as you haven't just driven 150 miles in 1.5 hours!).
More important is to use quality semi-synthetic oil of the correct grade, change it regularly (7.5 k km is OK), let the engine idle for a few seconds after starting it (easy on a BX as you have to wait for the suspension to come up!), do not thrash it when it's cold, and don't ever 'blip' the throttle as you switch off, as this potentially leaves the turbo spinning at 80,000 rpm with no lubrication, and that WILL knacker it!
When I changed the head gasket on my BX TD at 136,000 miles, after following the above routines for the 70k I had it, I found no roughness or excessive play in the turbo rotor.
Relax and enjoy[8D]
Yes diesel turbos run much cooler than petrol ones, so letting it cool down is much less important. If you've really been booting it (eg screaming up mountain passes on full boost) then it would be wise to let it idle for 30 - 60s before switch off. In normal driving, even if you come off the motorway into a service area, just letting the engine return to idle and waiting a few seconds will be OK (as long as you haven't just driven 150 miles in 1.5 hours!).
More important is to use quality semi-synthetic oil of the correct grade, change it regularly (7.5 k km is OK), let the engine idle for a few seconds after starting it (easy on a BX as you have to wait for the suspension to come up!), do not thrash it when it's cold, and don't ever 'blip' the throttle as you switch off, as this potentially leaves the turbo spinning at 80,000 rpm with no lubrication, and that WILL knacker it!
When I changed the head gasket on my BX TD at 136,000 miles, after following the above routines for the 70k I had it, I found no roughness or excessive play in the turbo rotor.
Relax and enjoy[8D]
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ActivaV6uk
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10-15 seconds is a good place to start only if you have really caned it should you let it cool longer (say 30 seconds to a minute). The problem isn’t that the turbo is spinning fast or (it will change form 10,000 rpm to 150,000 rpm in 1 second so it’s designed to cope with a lot (figures from turbo technics)). the problem is that if the turbo is hot and the engine is turned off then it has no oil going to it so the turbo then cooks the protective oil that is in its center bearing (this makes the oil unless when you start the car again and something that is moving on average at 70,000rpm should have oil protecting it!). If you let the car idle for 10 seconds the exhaust temperatures and general running heat drops by about 100 degrees + so the effects on the oil are less are less. If you can wait until the engines fans cut in and out then that is absolute best practice but it’s not possible to do that for most normal people. The best thing is you are changing the oil frequently this is a must and if you really do sick to this the engine and turbo will last for a very long time!
Andy
Andy
Aye to XantiaBFY's suggestion. In our hot tropical weather, its wise to have a turbo timer. Sometimes blasting up hillsides bring up the temperature to 100 deg, definitely switch on the turbo timer for 3 minutes wait. Just switch off and go on our merry way while the engine idles for 3 minutes without us waiting.