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Senior - BHPian Join Date: Feb 2004 Location: Mumbai
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| ![]() Mod Note : Please continue the discussion in our Turbos & Idling Article. Thanks When turbo engines were develeoped, engineers recommended that there should be at least one minute idling after starting and before switching off the engine to keep the turbo running properly and to prevent it from blowing pre-maturely. More improtant to have it idling before switching off the engine so that the turbo cools down. I don't know how many actually do it though. Now this is what I was planning to recommend customers buying a turbo charged car but from what I learn VW has engineered the new 2.0 Turbo in such a way that you no longer need to idle the engine. This is what I got after doing some research from owner manuals and VW's training site. The new engines have a coolant/(water?) cooled turbo. Even after you switch off the engine a little pump circulates coolant through the turbo for some time to cool it down. The user manual of both the turbo Jetta & Passat doesn't recommend the one minute idling thing for this new engine. I am quoting from the training site : To prevent carbon build-up on the turbine shaft in the turbocharger, an auxiliary coolant pump provides additional coolant circulation for a certain time after the engine is shut off hot. The pump forces the lower temperature coolant against the normal direction of flow. The coolant flows from the radiator through the turbocharger to the engine block and back to the cooler. The service manager has gone a small vacation so I still need to talk to him about this and I don't know if the older 1.8 Turbo engine had the same technology. The only pre-owned 1.8T Jetta on our lot is missing the owner manual so Octavia RS owners, ![]() Last edited by GTO : 28th January 2013 at 22:53. Reason: Adding link to turbo article |
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Team-BHP Support ![]() | ![]() In the UK, you find a lot of BMW diesels with blown turbos because of this very point |
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Senior - BHPian Join Date: Mar 2005 Location: N.A
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| ![]() I'm a bit concerned here - the Safari Dicors manual doesnt suggest this kind of idling, not does it carry a sticker that says its required. I've seen this sticker on the older Scorpio though...I still idle the vehicle before and after use, though. However, even after idling for say a minute or so there's a very distinctive hum of a turbine winding down AFTER the engine has stopped... On the Smart, I can hear the water pump humming away for about 1/2 a minute after I stop the engine. |
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Team-BHP Support ![]() ![]() | ![]() Quote:
Cooling may be one of the reasons, but certainly not the main reason. GTO | |
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Senior - BHPian Join Date: Feb 2004 Location: Mumbai
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Senior - BHPian | ![]() Quote:
When you switch off the engine without doing this exercise, the turbo keeps spinning with the residual lubrication. The high temp. prevalent in the turbo causes excess carbon build-up, also called coking of the oil. This hard coating causes the shaft to wear prematurely. So VW is combating this with cooling rather than pumping oil after switching off the engine. | |
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Team-BHP Support ![]() ![]() | ![]() The India/go turbos have this sticker on the door frame. Not a very obvious position. You can also look at unfamiliar places for the sticker. And yes you need to idle for a minute |
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Senior - BHPian Join Date: Mar 2005 Location: N.A
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The only sticker they've put on is one by the drivers side of the windscreen which relates to the usage of 4WD and how to shift back to 2WD. | |
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Senior - BHPian ![]() Join Date: Feb 2004 Location: Dubai/Bombay
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| ![]() Common Rail engines wouldn't require to do this idling I'm thinking. |
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Team-BHP Support ![]() ![]() | ![]() CRi is the method in which fuel is injected into the cylinder and has nothing to do with the functioning of a turbo. |
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Team-BHP Support ![]() ![]() | ![]() Inter cooler has no role to play in this start and shut business? ![]() Just asking all the gurus cause I don't know. |
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Senior - BHPian ![]() | ![]() The turbo timer - ie. Idling the engine for a minute is specifically to let the turbo spool down and continue supplying oil to the turbo while it is doing so. If you shut the engine the oil supply is stopped hence leading to a chance of caking on the turbo shaft. You get after market turbo timers for this too. Intercoolers have not6hing to do with the spool down of the turbo. However some cars come with oil reservoirs above the turbo which continue to gravity feed oil till the reservoir is drained, Such systems would not require to idle before shutting off. I am personally not too sure about the Dicor. |
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Senior - BHPian ![]() | ![]() splendid. now i knw something more. thanks to tbhpians. |
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Team-BHP Support ![]() ![]() | ![]() Best to be on the safe side and always idle for about a minute before shutting down. Although the Skoda manual has no mention of this, it is a practice I try and follow, if not for a minute then atleast for 30 seconds. However, the manual also states that its best to start driving at low rpm's as soon as possible after starting rather than letting it idle to get upto operating temperature. |
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