Been reading that turbos generally require time to cool down after being used, and not to switch the engine off straight away. Does anyone know whether this rule should apply to the Scirocco too? Or have VW put something in place which will cool it down when you turn the engine off anyway? I didn't notice any big warning in the manual (which I glossed over quickly), nor did the salesperson mention it at hand over time...
Wouldn't want to reduce the car's reliability, but at the same time don't fancy sitting in the car for an extra 3 minutes everytime I arrive somewhere!
Reliability
As long as the oil supply is clean and the exhaust gas does not become overheated (lean mixtures or retarded spark timing on a gasoline engine) a turbocharger can be very reliable but care of the unit is important. Replacing a turbo that lets go and sheds its blades will be expensive. The use of synthetic oils is recommended in turbo engines.
After high speed operation of the engine it is important to let the engine run at idle speed for around one to three minutes before turning off the engine. For example Saab, in its owner manuals, recommends a period of just 30 seconds. This lets the turbo rotating assembly cool from the lower exhaust gas temperatures. Not doing this will also result in the critical oil supply to the turbocharger being severed when the engine stops while the turbine housing and exhaust manifold are still very hot, leading to coking of the lubricating oil trapped in the unit when the heat soaks into the bearings and later, failure of the supply of oil when the engine is next started causing rapid bearing wear and failure.
The only thing I've seen in the manual is that it says something about if you've been driving particularly keenly for a reasonable amount of time you should give it 2 minutes to cool down before turning off.
I'll see if I can find it in the manual again tonight.
Kev wrote:The only thing I've seen in the manual is that it says something about if you've been driving particularly keenly for a reasonable amount of time you should give it 2 minutes to cool down before turning off.
I'll see if I can find it in the manual again tonight.
From experience I would say a cool down is only required after a sound thrashing... also remember the standard unit is tuned well down from max potential so will never be fully stressed even when run at full tilt (all modern cars are tuned to 70-80%) so a lengthy cool down will not be required, if it was they would have built in a turbo timer rather than fork out for all the warranty work on blown turbos. That been said if you chip your car to get the extra 20-30% out of it you will be pushing the components close to (and beyond in some cases) the limit and a cool down would be required. I also own a Quattro Turbo that I track regularly and always use the last lap to trundle round on no boost to allow it to cool down sufficiently before returning to the paddock.. incidentally also never put the handbrake on after a good thrash especially where you have been hard on the brakes as the pads can get welded to the discs!!
now modified with dump valve, boost gauge in custom made vent, "gt" steering wheel badge, carbon fibre badges, rs4 wheels, lowered 35mm, private plate S18OCO, custom de-cat and cat back exhaust with quad tips, air filter behind fog lamp heat wrapped, customised front bumper grills painted gloss black, customised rear bumper smoothed and lower spoiler painted gloss black, mouldings and mirrors sprayed in gloss black, gloss black roof and rear spoiler, colour coded dash trims, door trims, centre console trims and rear seat trims, led fog light bulbs, s3 intercooler, audi a4 "S line" gear knob, newspeed hi-flow throttle body pipe, newspeed hi-flow turbo pipe, uprated dog mount bush, front to back and side to side quickshift, 20mm front spacers
like it has been said above, there isnt a "need" to do it if you have been driving half normal, but if you have been thrashing it, then its better off if you do let it cool down for a few minutes
Agree with the above, my MKV GTi used to keep the fan on when you turned the engine off if it was hot and you had been driving fast, I suppose the roc will do similar.
Also, another point, these turbos spin at ridiculous speeds (100,000 rpm) and thus you can see the need for adequate lubrication. Thus, think carefully before you boot it from cold. Even when the temp gauge gets to normal, the oil is still a few minutes behind. If you have ever driven a car with an oil temp gauge you would of seen this so be wary and try to moderate the use of full throttle until fully warmed up, especially if you intend to keep the car long term.
Taken delivery : Silver, DSG, NAV, Black Leather, Park Sensors, Winter pack.
Mods: Full Milltek, KW lowering springs,Wheel Spacers, Remapped to 258BHP, 405Nm
I found an official VW 56 page technical document on the 2.0 TSI engine which describes the working of each system in detail complete with diagrams. I have extracted the following on cooling system which states an 'After-Run Cooling Pump V51(Electric) runs after engine shut off to cool the turbo". Read in engine control module section that pump V51 runs for approx 142 seconds after engine is switched off.
Its a Volkswagen! Stop worrying!
Engine Cooling System
The engine uses a cross-fl ow cooling system. Engine
coolant fi rst fl ows to the front of the engine from
the coolant pump. The coolant is then distributed
along ducts and circulates around the cylinders. After
circulating through the cylinder head, the coolant
is routed back to the radiator via the thermostat
housing or recirculated through the coolant pump if
the thermostat is closed.
The heat exchanger and turbocharger are part of
the engine cooling circuit. The engine oil cooler is
connected directly to the cylinder block through its
mounting subframe.
After-Run Coolant Pump V51 protects the
turbocharger bearings from overheating after engine
shut-off.
The pump is activated by the engine control module
based on programmed characteristic maps.
mruddy wrote:I found an official VW 56 page technical document on the 2.0 TSI engine which describes the working of each system in detail complete with diagrams. I have extracted the following on cooling system which states an 'After-Run Cooling Pump V51(Electric) runs after engine shut off to cool the turbo". Read in engine control module section that pump V51 runs for approx 142 seconds after engine is switched off.
Its a Volkswagen! Stop worrying!
Engine Cooling System
The engine uses a cross-fl ow cooling system. Engine
coolant fi rst fl ows to the front of the engine from
the coolant pump. The coolant is then distributed
along ducts and circulates around the cylinders. After
circulating through the cylinder head, the coolant
is routed back to the radiator via the thermostat
housing or recirculated through the coolant pump if
the thermostat is closed.
The heat exchanger and turbocharger are part of
the engine cooling circuit. The engine oil cooler is
connected directly to the cylinder block through its
mounting subframe.
After-Run Coolant Pump V51 protects the
turbocharger bearings from overheating after engine
shut-off.
The pump is activated by the engine control module
based on programmed characteristic maps.
Phew... I was worried for a while
But I bet you will still find some 3rd party turbo timers installed in time... not becasue they need one but just bacasue they are barry's.
now modified with dump valve, boost gauge in custom made vent, "gt" steering wheel badge, carbon fibre badges, rs4 wheels, lowered 35mm, private plate S18OCO, custom de-cat and cat back exhaust with quad tips, air filter behind fog lamp heat wrapped, customised front bumper grills painted gloss black, customised rear bumper smoothed and lower spoiler painted gloss black, mouldings and mirrors sprayed in gloss black, gloss black roof and rear spoiler, colour coded dash trims, door trims, centre console trims and rear seat trims, led fog light bulbs, s3 intercooler, audi a4 "S line" gear knob, newspeed hi-flow throttle body pipe, newspeed hi-flow turbo pipe, uprated dog mount bush, front to back and side to side quickshift, 20mm front spacers
