285cupra-matty wrote
I have been told but quite a few people several of whom are mechanics, say that the water pump don't do s#@t for the turbo,
when U put your foot down and hit boost you spool the turbo yes?
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Yes. What has this to do with the price of fish?
So this motion in the turbo takes a while to slow down and the turbo's on Leon are water cooled yes?
Only on the LCR. To deal with the high temperatures they reach in full-bore running. Not because they need it when pootling along at 3000 rpm.
And oil lubricate's the compressor wheel bearings so if you turn the car straight off yes the water will be pump round ( if the pump still works) but the oil pressure will stop as soon as the engine stops turning thus starving the bearings of oil causing wear eventually allowing oil past making it like a ford SMOKEY.
The turbo bearing (there's only one) is lubricated and cooled by oil flowing at a very high rate, because it's a plain bearing rotating at enormous speed and because being in the exhaust it gets very hot.
Even if you were to pull in off a racetrack after a sustained session of full-bore antics and switch the engine off straight away, the turbo stops spinning straight away too. it doesn't take minutes to slow down, and once the engine is off it's under no load. It's driven by the exhaust gas after all. The turbo components, exhaust manifold and engine will be very hot. The continued flow of coolant will bring the temperature down sooner. You'll still have cooked some oil in the bearing, though.
In real life, there is usually some slower driving before you switch the engine off, which allows the turbo to cool off. The worst situation I can think of would be pulling into a motorway services after a mad session of illegality. In circumstances like those, don't switch your engine off straight away.
Someone will correct if im wrong.
ObWhinge: spelling, txt-spk etc.