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youngsyr
6,795 posts
61 months
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kpb said: youngsyr said: Why would your turbo need cooling down after a cruise on the motorway?  I dare say someone will correct my mechanical knowledge but warming turbos up and down is generally deemed to lengthen their lifespan - I think its something to ensuring the oil & unit temps in them are reduced slowly as opposed to just instantaneous drop off when temps are high. Hence the option to fit something like this... http://en.wikipedia.org/wiki/Turbo_timerObviously pulling off a motorway after an hour at 70+ mph (or a spirited b-road drive ending at some lights) and the stop start kicking in is somewhat counter to this. Your turbo won't be that hot after a motorway cruise - in fact it's probably the coolest it will ever run whilst you're driving as it won't be producing any boost, the engine is under low load and you will have maximum airflow through the engine bay and oil cooler (if fitted). You may find that parking the car up with the engine running will actually increase the turbo's temperature due to heatsoak and no airflow. Coming from a high pressure turbocharger background (Evos) the fitting of turbo timers was generally frowned upon.
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kpb
218 posts
44 months
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youngsyr said: Your turbo won't be that hot after a motorway cruise - in fact it's probably the coolest it will ever run whilst you're driving as it won't be producing any boost, the engine is under low load and you will have maximum airflow through the engine bay and oil cooler (if fitted).
You may find that parking the car up with the engine running will actually increase the turbo's temperature due to heatsoak and no airflow.
Coming from a high pressure turbocharger background (Evos) the fitting of turbo timers was generally frowned upon. Fair enough on the motorway, probably a bad example (although of course it depends on what speed/gear you've been using I guess!) But the same applies for a spirited drive elsewhere using higher engine RPM etc. Come to a set of lights and instantly kill the engine? Doesnt sound wise to me whether its a BMW diesel, high pressure Evo or other turbo'd car? Interesting point on the Evo school of thought though. I've heard different via Subaru sources but admittedly third hand.
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stuart-b
2,588 posts
95 months
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If the turbo is too hot, the stop start doesn't kick in. So many reasons for it not to kick in, yet, mine always seems ready to do it at the worst time 
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Mabbs9
17 posts
87 months
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To bring this back to life for a mo, I've bought a BM recently, still in warranty but 48000miles. I agree that the stop start could cause some extra wear. When cold starting all,sounds normal, sometimes when hot I hear a slight clunk/rattle sound as th starter disengages. Anyone care to suggest possible reasons?
I wonder if these cars have a DMF, I have a very slight judder sometimes when letting the clutch in, possibly some clutch wear but happy for thoughts.
Thanks.
Chris
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