After driving NA cars for years I now find myself driving a turbocharged engined car (TA) for the first time. I read an article that there are certain things you can get away with in a NA engine that are bad for a turbo. Two of those, in particular, stick in my mind - that is 'lugging' - getting the engine to pull along in high gears at low revs/low speed especially uphill. The second one is turning the engine off when the turbo is hot. The latter one concerns me most as my car has stop/start. Could stop/start shorten the life of a turbocharger?

Don't worry. Firstly, Stop/Start stresses many things and saves you almost nothing in fuel. Turn it off like everyone else.

Secondly, the turbo advice you have re. not turning the engine off hot does not apply. That advice is for oil cooled turbos. You have an oil and water cooled turbo, so this is not a factor. Just don't rev hard for the first 5 mins each day and you'll be fine.

I think the advice about idling a hot turbo charged engine is to do with the engine oil to and from the bearing in the turbo.

The oil has been know to carbonise in the oil feed pipes of turbos, which limits or totally blocks the oil reaching the bearing.

The bearing is actually just a plain bearing (a loaded surface not a race of balls or rollers). The turbo's spindle "floats" in a wedge of oil which is forced into a small clearance under pressure.

The oil not only lubricates the turbo's bearing (and everything else) but also has a cooling effect.

After switching off, the oil is no longer under pressure, there's no longer the oil wedge in the plain bearing as it drains away to the sump, but some is trapped in the pipes and bearing of the red hot turbo which, if hot enough can burn and carbonise and block the passages.

Which is why the advice is to run it down to let it cool a little after a hard drive, but still have a supply of engine oil to it (and coolant if it's water cooled).

The trend these days is to aid the cooling of the turbo in various ways like water cooling and to an extent these efforts do work most of the time, but they do require a running engine, no engine running = no oil circulation and no coolant circulation!

If I stop after a long motorway run, I'll still idle for a minute or two.
Shuffling around locally in traffic, there's little chance the turbo would be hot enough to cause a problem, not that my S/S ever worked!

There have been many that have replaced knackered turbos without changing their pipe work and their replacements have gone the same way soon after as it was blocked oil feed pipes that caused the problem in the first place.

AndyCalling said:

Don't worry. Firstly, Stop/Start stresses many things and saves you almost nothing in fuel. Turn it off like everyone else.

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Don't turn off the stop/start, just use it sensibly and responsibly. It may not save you a great amount of fuel but it will greatly reduce your pollution output and protect those around.

Use the clutch to control it. Keep it down and S/S won't cut in. If you are at traffic lights that have just gone red then let it cut in as you'll be a minute or so. If dropping off the kids definitely don't sit there with the engine idling as their brains are more susceptible to damage from pollution.

Nick

Well my stop/start does work at the moment but I agree - I do question the wisdom of constantly switching the engine on and off. The only time that seems to makes sense is if you're stuck waiting at a level crossing for a while - otherwise it's an annoyance more than anything else - I don't like holding my car on the footbrake I like to use the handbrake and neutral so it's always deploying if the engine is warm enough.

Stop/Start was primarily introduced to play the carbons game during the NEDC testing phase, to get the CO2 measurements as low as possible. The amount of fuel it saves during the switched-off phase is WAAAY outdone by the extra effort over the life of the car of tooling around with a massive battery twice as big and heavy as it needs to be, just to ensure that S/S can Start again after an Stop with the lights, heated seats, AC and stuff all on at the same time. Starter motors are bigger and heavier than they need to be too. Even with a battery the size they are, S/S still has plenty of times when it won't engage, as the Current draw v's battery State of Charge maths simply don't add up.

I'm all for sensible use of switching off, ie: right outside school gates (when most of the Ego Panzers park of course), or in traffic jams in villages, but ultimately I fear S/S is a gimmick to keep the bureaucrats happy ultimately.

So that's 2 rants in two days, sorry - must be getting old

On a plus point the 'carbons game' did give us the flawed and quirky gem of an engine like the TA. Which probably does not make any sense from a 'good sensible, simple engineering' point of view but I think the automotive world is better for it. So every cloud (of emissions)...

JCarp16 said:

Well my stop/start does work at the moment but I agree - I do question the wisdom of constantly switching the engine on and off. The only time that seems to makes sense is if you're stuck waiting at a level crossing for a while - otherwise it's an annoyance more than anything else - I don't like holding my car on the footbrake I like to use the handbrake and neutral so it's always deploying if the engine is warm enough.

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Its a shame a few more people don't follow suit instead of inconsiderately dazzling everyone behind them by keeping their foot brake on. From me a BIG thankyou for your common sense. Suffice to the people who insist on holding on the footbrake wouldn't pass and advanced test driving like that. If the are ever rear ended they will find out why its poor practice.

I ran a 2.2 Laguna diesel for many K's a few years back and after a lot of effort decided stopping the engine at traffic lights in traffic was worth around 6mpg. With the modern systems in use with stop start all sorts of things are altered to make the stress on the engine less. A good system can be more or less ignored and should be unnoticeable if used right. I had a company Hyundai where the system did seem a pain in the rear end so I do understand people turning them off. In my Panda the system seems bomb proof so far. I am glad not to using teh m25 any more in the rush hour, which is where it would work at its best.

Don't worry, in 10 years time we all drive electric, no more Start-stop systems.

JCarp16 said:

Well my stop/start does work at the moment but I agree - I do question the wisdom of constantly switching the engine on and off. The only time that seems to makes sense is if you're stuck waiting at a level crossing for a while - otherwise it's an annoyance more than anything else - I don't like holding my car on the footbrake I like to use the handbrake and neutral so it's always deploying if the engine is warm enough.

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You can do that, handbrake and neutral, but just keep the clutch down to keep the engine running or take your foot off it to engage stop/start. Simples.

Nick

Post 3 from Goudrons sums it up nicely.

If you've just done a fast run, don't allow the stop/start to operate. For normal driving it should be fine.
When you end a journey, allow the engine to idle while you turn off lights, wipers, heater, radio, etc., then turn off the engine.
Don't miss service intervals, and use the right high quality oil. Turbos don't tolerate wrong oil.

I do a lot of corporate training in cars with stop start, and driving a route with it off, then same route on, always shows a significant difference in fuel consumption, so there is merit in the system. But, as the battery and starter life must be reduced, I wonder if we'll save enough money on fuel to pay for the new batteries and starters.

The stop/start is great at pedestrian crossings. We've all had times when faced with a flashing amber, or green light, more pedestrians start to cross, just following the crowd. At that time, down goes the clutch, engine restarts, that alerts the pedestrians who check the lights and stay on the footpath. It's worked every time for me so far. Great trick.

The Fiesta school car has a water cooled turbo. I had a pupil on a fast road, so would arrive briskly, turn into his drive, spin the car around and engine off. Moments later we could hear the water boiling violently into the expansion tank from the turbo. Sounds like a kettle. Great fun, must be bad for the turbo. Moral, consider carefully the history of any used car.