I am a little concerned about using the stop/start system and what is usually recommended to maintain the longevity of a turbo. Basically, it is advised to allow the engine to run at idle for a period after completing a journey to allow the turbo to cool down a bit before turning off the engine as this prevent vaporising the oil etc. However, the stop/start system will stop the engine immediately the car comes to a halt with the foot brake applied no. Matter how hot the turbo is. Does anyone have any particular thoughts on this anomaly?

Don't think there's anything in the manual about letting the turbo cool down..... Plus I'm 99% sure there's a electric coolant pump that runs after the engine is switched off.

It will be fine, it is designed to work with start stop so I am sure cooling is not an issue, not sure about the engine you have but some of the diesels have water cooling to the turbo.

I had similar thoughts about the DPF.  We know that short journeys are bad for them but surely start/stop technology replicates a series of short journeys?

I had similar thoughts about the DPF. We know that short journeys are bad for them but surely start/stop technology replicates a series of short journeys?

No, issues from the short journeys come from starting from cold.

I am thinking in the same manner as philbritton. And more...S/S will involves other damages in time. I try as much as i can to stop SS and activate it only when i want.

SS is intended to save fuel theoretically but is more a marketing strategy. The are presuming the buyer will keep the car around 2 years.

Edited 23 February, 201412 yr by myself24483

I am thinking in the same manner as philbritton. And more...S/S will involves other damages in time. I try as much as i can to stop SS and activate it only when i want.SS is intended to save fuel theoretically but is more a marketing strategy. The are presuming the buyer will keep the car around 2 years.

Stop start does save fuel though, when it's stopped it doesn't use any! And you say they assume the buyer will only keep the car 2 years then why give it a 3 year warranty, surely it'll then cost the manufacturer to repair the car?

I think it's more a case of people on the Internet thinking they know better than car manufacturers.....

We seem to have returned to the scaremongering days once again. Rest assured, your Octavia won't catch fire, fall apart or have some other major component failure because of stop/start, DPF or any other bit of technology that the manufacturer has installed. They spend millions of pounds on developing new cars for a reason.

Probably also worth noting that none of the bits mentioned above are particularly new tech. It's been around for a number of years and is tried and tested.

 

Alternatively, you could buy a Mk2 Golf or a new Dacia and you won't have to worry about any of it. (not that you should in the first place)

I was told by a turbine designer that the problem with old fashioned automotive turbochargers was the lack of lubrication during "spin down" if the engine was revving above tick over, and so the turbo impeller would be to,  when the ignition was turned off. The solution was to only turn off ignition, and consequently stop lubrication pump when at tickover speeds.

Modern SS systems fully power all ancillary systems during the stop phase hence headlights, radio and cooling fans still working and "smart" dpf regen systems solve that issue as well.

Manufacturers are notoriously bad at offering warranty for anything that might fail at their cost, longer warranties suggest very strongly that longevity will exceed cover offered, Kia offer a 7 year warranty so they must be confident!

Thank you all so far for your inputs!

I was told by a turbine designer that the problem with old fashioned automotive turbochargers was the lack of lubrication during "spin down" if the engine was revving above tick over, and so the turbo impeller would be to,  when the ignition was turned off. The solution was to only turn off ignition, and consequently stop lubrication pump when at tickover speeds.

Modern SS systems fully power all ancillary systems during the stop phase hence headlights, radio and cooling fans still working and "smart" dpf regen systems solve that issue as well.

Manufacturers are notoriously bad at offering warranty for anything that might fail at their cost, longer warranties suggest very strongly that longevity will exceed cover offered, Kia offer a 7 year warranty so they must be confident!

 

It is not the lack of lubrication during "spin down" that is the problem, it is the excessive heat generated during any period of full power use (up to nearly 1,000 deg C on the exhaust outlet side on some modern petrol engined turbos). The lubricating oil and coolant will help dissipate this heat as long as it is flowing. If the turbocharger has had a cool down period after hard use it should be fine. Don't barrel down the motorway at vmax then pull into a service station and immediately switch off!

Edited 24 February, 201412 yr by Timoctav

I take it you can disable the stop start system ?

I take it you can disable the stop start system ?

Yes

I take it you can disable the stop start system ?

Yes

 

 The lubricating oil and coolant will help dissipate this heat as long as it is flowing. If the turbocharger has had a cool down period after hard use it should be fine. Don't barrel down the motorway at vmax then pull into a service station and immediately switch off!

I was told the same. Motorways/ service stations are the main problems. On most other occasions you would have been travelling a while at a slower speed before switching off. Hence turbo should have cooled down sufficiently.

Don't think there's anything in the manual about letting the turbo cool down..... 

 

The manual actually recomends idling at the end of the journey:

 

? Do not switch the engine off immediately at the end of your journey after the

engine has been operated over a prolonged period at high loads but leave it to

run at an idling speed for about 1 minute. This prevents any possible accumulation

of heat when the engine is switched off.

 

It seems to me that this advice is left over from older manuals, because it is strange that there is no mention of start/stop, as almost all engines for the O3 have start/stop. They probably decided to leave it just in case.

 

Anyway, it is probably a good idea to follow any recomendation or warning in the manual. On the day of the pickup, the technician also told me that leaving the engine running for a minute or two after long highway journeys would extend the life of the turbo.

I never use stop start system no matter what the journey it is always turned off when I start the car. I also allow car to sit at idle after every journey for circa a minute. I will be enquiring with dealer when she is in for her first service if the system can be disabled or coded the opposite way (I.e it's off everytime car is started and can be activated by the button) I didn't but the tsi vrs for fuel economy

I've found it odd as well that when you stop the car (put it in P), S-S immediately shuts off the engine. Until now I haven't been able to cover the "barrel down the motorway at full speed then stop and park" scenario, so I don't know if in that case the S-S system won't kill the engine.

 

You'd think the engineers would use the engine sensors and decide not to let S-S kill the engine in certain scenarios (as there's a long list for that already)...

My opinion is that it is not worth bothering with a cooling-down period at all. VAG turbo's run at low pressure and have relatively good cooling.

 

The main danger (for older cars) was when turning the engine off immediately after running the car very hard. The oil would immediately stop pumping around, and if the turbo was "cooking" it could result in burnt oil. This burnt oil would then clog up the turbo internals (similar to cholesterol blocking arteries), eventually causing failure through lack of cooling and seizure. Modern turbo's run much cooler, modern synthetic/semi-synthetic oils are much more tolerant to abuse, and stop-start rarely results in long periods or rest after long periods of hard driving.

 

If you intend driving a few hot laps at the Nurburg then it may be worth allowing the engine to idle for 5 minutes afterwards, but otherwise don't bother. 

 Modern turbo's run much cooler, modern synthetic/semi-synthetic oils are much more tolerant to abuse, and stop-start rarely results in long periods or rest after long periods of hard driving.

 

If you intend driving a few hot laps at the Nurburg then it may be worth allowing the engine to idle for 5 minutes afterwards, but otherwise don't bother. 

 

Disagree. FYI modern turbochargers actually run higher exhaust temperatures to increase efficiency. Diesel engine turbos don't run at anything like such high temperatures as petrol though (probably in the region of 450 deg C - but still hot enough to cook and carbonise oil in the bearings through heat soak.

 

http://www.3k-warner.de/en/products/turbochargerPassengerCarsGasoline.aspx

Edited 24 February, 201412 yr by Timoctav

I've found it odd as well that when you stop the car (put it in P), S-S immediately shuts off the engine. Until now I haven't been able to cover the "barrel down the motorway at full speed then stop and park" scenario, so I don't know if in that case the S-S system won't kill the engine.

 

You'd think the engineers would use the engine sensors and decide not to let S-S kill the engine in certain scenarios (as there's a long list for that already)...

 

That was an extreme scenario - but all the turbo engined cars I've owned, particularly petrol ones, I've always run on idle for a minute - good engineering practice, as they say.

 

but all the turbo engined cars I've owned, particularly petrol ones, I've always run on idle for a minute - good engineering practice, as they say.

Totally correct and I see no good reason to stop doing this even on a diesel

My first car with stop/start was a 123D BMW. I bought it in 2007 and as far as I know, these cars are still driving around fine with no major issues related to the S/S. I know a colleague who has a 6 year old coupe version and has had no issues, despite driving it like he stole it. This is quite a high powered diesel too, producing just over 200bhp from a 2 litre, so I am guessing it might get quite warm when being thrashed