well im just going on what the manuel says in my manuel my car says after a long run, let the car idle so the oil can flow throughout the turbo i think but i still let it idle because sometimes i do hammer it down the bypass....... because its fun,
I just get in a drive in my diesel, no point letting it idle as it does nothing and only means when you do drive it a big thick cloud of smoke appears. I just drive it gently rising the rev's slowly and no greater than 2krpm. Takes my car about a good 5 miles to warm up normally. I see plenty of 'suit it and boot it' business men flooring their cars in the morning off their drives. I drive 35miles to work pretty much sitting at 2200rpm so when coming off the junction with a 2 mile drive to go, i just take that steady to cool the engine down.
exactly, they dont need to worry because if it goes wrong company pays for it, my uncle does the same with his Corolla Verso but he's sooon to get rid and get a VAG Audi A4 2.0 TDI,
Yes turbos definatly spin when the car is idling. I have seen turbos that you can blow down with your own mouth and the blades start to spin so a 2 litre engine with exhaust gases going through it (2 litres per rev, 800 revs a minute) is blowing lots of air through. Of course it is spinning. What people are getting confused about is how fast its spinning. At idle it is relatively low but when producing boost it can be 80,000 and 200,000 RPM (using low inertia turbos, 150,000-250,000 RPM). That is why there is turbo lag and why belt driven superchargers like they use on VR's are a bit poo imho. Even with a load of pulleys etc, they are never going to spin that fast that far down the rev range. Agains, the heat is all relative. When you've got your foot flat on the floor and its producing power, it is also producing heat. 900 decree C. When your driving sensibly, your more likely to se 400 - 500 degree's C, and even lower at idle. So yes, Idling will allow your turbo too cool, but its still ****ing hot. But thast not the main reason you let a turbo car cool down before you switch it off. Imagin you've been ragginf the t1ts of your car the turbo is spinning at a quarter of a million RPM and then you switch your engine off. Turbo still spins. Maybe not at 250,000prm, but still alot. No new oil is coming through to it. The oil drains out of the turbo, and or gets vapourised by sitting in a 900 degree turbo. And th bearings don't like to spin without lubrication. A sure fire way to shag a turbo, very quickly.
According to Volkswagen you shouldn't leave the car idling from cold start but should instead drive pretty much straight off, however, you should not use excessive revs or full throttle until the enging oil is warmed through. General rule of thumb is stick the MFA on engine oil temp setting, drive the car gently at part throttle/low revs at lease until a reading is shown on the MFA - under 50 degrees all you get on the MFA is "---" I don't give mine any abuse at all in the first ten minutes of a drive or the last ten mintues either.
Not true. The bearing damage occours because the 900 oC speeps through to the stationary bearings and bakes the residual oil onto the bearing material. The bearings don't like to spin with soot in them.
Something else people have failed to mention.......OIL PRESSURE!!!!!!!!! Fit a separate oil pressure gauge & watch it when you 1st start it up & while the engine is warming up, you will be surprised how long it can take to settle down sometimes along with oil temp. I have a pressure guage in the mk1 along with a separate oil temperature gauge which i would always watch & wouldn't boot it until temps were up (not always shown on a dash engine temp gauge).
How is what I said not true? Is soot being in the bearings a good source of lubriacation? No it isn't therefore, it has no lubrication. Therefore it gets ****ed. Which is what I said, whithout adding the word "soot".
some good replies in this thread. this is the best one. when the engine has just started the oil pressure is very high as it is thicker, harder to push. not a good time to be booting it. i let the golf get to 70degrees before pushing on a bit. the 200 i let the oil pressure drop to the warmed up pressure before letting the turbo loose and then slow for the last few minutes of the journey to help them cool
Mark is actually right, much as I hate to admit it. Your turbo stops spinning within 4 or 5 seconds max after you switch off. So does the oil pump, of course. So you have oil sitting in your red-hot turbo, not circulating, and it carbonises. Turns to dirty old soot or worse still, hard carbon deposits. That blocks oilways and the like, and over (lots) of miles, will kill the turbo. The proper way to do it, as mentioned before, is to let the engine idle for a bit after a hard run before you switch off. The turbo cools down, the oil is still flowing, and once you switch off everything is as nice as a shaven ball-sack.
iirc they had an after market piece of kit for turbo's that would keep things spinning or summit? after the engine was shut off, this was back in the early 90's i heard about it.
my 1st build of my 2.1 8v had 125,000+ miles of hard driving out of it before a rebuild, rev limiter every gear every day but i always watched the oil pressure & oil temps before each run so either i was just lucky or something worked for me.
here you go fellow marine http://www.edition38.com/forums/index.php?showtopic=128422 the answer was basically; 'You car will be on fuel enrichment from cold start. If you do not put any load on the car by driving it then it will continue to overfuel whislt it warms up causing premature bore wear. You should start it, give it a few seconds to build up oil pressure then drive it gently until the oil temp comes up. '
