Is using auto start-stop bad?

Zandoni

As most of us know an engine wears most when it first starts up, oil circulation being one of the causes. I realise it's not as bad when a warm engine is restarted but there must be a degree of oil draining from the bores and a lower pressure at the bearings at each restart.

WellKnownSid

Zandoni wrote: »

As most of us know an engine wears most when it first starts up, oil circulation being one of the causes. I realise it's not as bad when a warm engine is restarted but there must be a degree of oil draining from the bores and a lower pressure at the bearings at each restart.

Yes, the "big end's gone" - I remember that phrase last being used on a TV soap about 30 years ago.

Someone once said on here that starting an engine is the equivalent of 500 miles of driving. Which means I must do at least 25,000 miles every week and my car really has close to two million miles on the clock. In just 18 months.

Cool!

Zandoni

WellKnownSid wrote: »

Yes, the "big end's gone" - I remember that phrase last being used on a TV soap about 30 years ago.

Someone once said on here that starting an engine is the equivalent of 500 miles of driving. Which means I must do at least 25,000 miles every week and my car really has close to two million miles on the clock. In just 18 months.

Cool!

Well that's all a bit silly, but increased engine wear is a possibility.

RichardD1970

All the people saying this and that will go wrong:- don't you think that the people who actually design, engineer and manufacture these things haven't already thought of this and designed/re-engineered components/systems to account for this?

No manufacturer wants to get a reputation for shoddy engineering and a higher level of breakdowns from their vehicles.

Zandoni

RichardD1970 wrote: »

All the people saying this and that will go wrong:- don't you think that the people who actually design, engineer and manufacture these things haven't already thought of this and designed/re-engineered components/systems to account for this?

No manufacturer wants to get a reputation for shoddy engineering and a higher level of breakdowns from their vehicles.

Of course they don't, but who knows what manufacturers get up to, they have made many mistakes in the past, without even mentioning VW.

WellKnownSid

Zandoni wrote: »

Well that's all a bit silly, but increased engine wear is a possibility.

The whole "most of the engine wear occurs during the first x miles of driving" was born during a different era, something that happened because of many factors.

Looser tolerances kept oil pressure down and means even thicker oil doesn't flow through the engine so quickly. That said, at 80rpm during engine start, and under no significant load - the wear is not great.

The biggest wear - bore wear - is a feature of over-fuelling. Remember that little knob you had to pull out to get your car to start? Remember the car spinning over like a jet engine on a cold morning? Compression lost because the oil was being washed down the bores by too much fuel - and even if you did get started that little knob kept pouring petrol down the bores

Zandoni

WellKnownSid wrote: »

The whole "most of the engine wear occurs during the first x miles of driving" was born during a different era, something that happened because of many factors.

Looser tolerances kept oil pressure down and means even thicker oil doesn't flow through the engine so quickly. That said, at 80rpm during engine start, and under no significant load - the wear is not great.

The biggest wear - bore wear - is a feature of over-fuelling. Remember that little knob you had to pull out to get your car to start? Remember the car spinning over like a jet engine on a cold morning? Compression lost because the oil was being washed down the bores by too much fuel - and even if you did get started that little knob kept pouring petrol down the bores

Nope it's still the case even with modern engines.

Gloomendoom

victor2 wrote: »

I heard from a mechanic that the Ford "EcoBoost" engine fitted in some Fiestas is a turbo charged engine and the turbo of course runs at high speed and gets very hot. The stop/start on that engine also stops the turbo without allowing it to idle and cool down. It does this repeatedly in typical city driving. As these engines are getting older, there are reports of the turbo casing cracking due to the build up of temperature and inadequate cooling in stop/start city driving. That is a very expensive repair...

Ask the mechainc if has ever heard of water cooled turbos.

A._Badger

RichardD1970 wrote: »

All the people saying this and that will go wrong:- don't you think that the people who actually design, engineer and manufacture these things haven't already thought of this and designed/re-engineered components/systems to account for this?

No manufacturer wants to get a reputation for shoddy engineering and a higher level of breakdowns from their vehicles.

That's not much of an argument. The history of car design is littered with examples of manufacturers making just such mistakes. Entire reputations have sometimes been put at risk - ask Mercedes.

In the current climate, where car design is so heavily influenced by legislation, it doesn't seem at all far fetched to infer that poor engineering decisions could be induced by the need to meet government targets.

WellKnownSid

Zandoni wrote: »

Nope it's still the case even with modern engines.

I'm not aware of any modern engine that has a choke...