I have a diesel Mondeo, the first time I've owned a diesel. The general advice is to let the revs die down before switching off the engine, which I try to do. Can someone explain these questions ?
Does the turbo only work when you are using the engine's performance, and not when driving at lower speeds, such as in a built-up area ? I know when you accelerate there is quite a surge of power after a moment.
When I do turn it off, what is the noise that keeps going for a couple of seconds, like a cooling fan. There is no such noise on the non-turbo work LDV van, although it is noisy anyway.
I find I rarely need to use the acceleration to the full, as it has plenty of go without chasing it.
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The thing is to let the engine idle for a few minutes to let the turbo and its bearings cool down but this is only necessary if are going to shut down having come straight off some hard driving ie a motorway. If you drive a couple of miles thru a built up area and then swtch off, the turbo will not have been in use and will already be cooled down, so far as I understand it
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the reason is to allow the oil in the bearings of the turbo to circulate and thicken ,,then when it is next started ,there will be oil around the bearing.when you have really hot oil, it is thinner,, so when you turn off the engine with this thin oil it drains quicker from the turbo bearings,,,there fore if you allow it to cool for a minute or two,,,it is still pumping around but at a thicker viscousity,,,so leaving a coating for when you next start up.
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www.storme.co.uk
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Driven normally, there is absolutely no reason why a turbo charged engine can't be stopped and started as a non turbo engine.
I work as a mechanic for a vehicle rental company, (100 or so vehicles), most of them are turbocharged, and I've yet to see a turbo fail.
Most turbo related problems are down to air and oil leaks.
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There is some useful torbo information to be found here:
www.turbotechnics.com/turbo/faq.htm
number_cruncher
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many thanks for your comments
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The handbook for my Metro Turbo mentioned idling for a few minutes after a fast run but none of the handbooks for cars I've had since (all turbos) mention the same point. As mentionedabobe 'tis good policy to let the turbo cool down before switching off. The reason given for the Metro was heat soak denaturing the oil if switched off when too hot.
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I think it's a bit of an old wives tale...
Many turbochargers are watercooled these days to prevent the problems. Modern oils are much better than the black death sludge forming oils of decades gone by.
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www.honestjohn.co.uk/forum/post/index.htm?f=4&t=13...9
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Try this: go for a blast in your turbo car. About 5 miles should do, but make sure there's some full throttle work in there.
Pailton (Warks) to Lutterworth (where I live) is 7 miles thro' good B road and 1.5 miles dual carriageway followed by 0.4 miles through the estate onto our drive. Rover 820 turbo (the 200bhp one) with water cooled Garrett T25. Give it 'loads' on the B road and then full throttle all the way down the dual. Gently into the estate and straight into the dark garage. Up with the bonnet. Stand well back - the heat is unbearable on your face. Turbo glowing a lovely bright orange. leave car to idle with bonnet up. Takes 10 mins before there is no discernable glow left in the turbo.
After any heavy throttle work withing 5 miles of home or after a long run I now leave my car to idle for as long as it takes for the fan to cut in and out twice. Usually about 10 mins.
The previous owner was a car nut like me and did much the same. the car has now done 138k and drives like new (admittedly it is maintained to the highest standard). Had the cam covers off recently. Clean as new in there. Good indication that the turbo bearings are probably in similar condition. That's the way i want it to stay, because it's my car and I'm the one who'd have to shell out the hard earned if the turbo failed prematurely.
Also, if you could stand in any OEMs warranty return centre (like I do) and look at the insides of pallet loads of turbos returned under warranty, you'd realise that a turbo is not a fit-and-forget item. Treat it with care.
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