Genuine mileage on cars?

the true miles wont show on a diag unless you go looking for the miles in the ecu i would guess if some one is going to clock a car it will be in the first 3 years of its life prob in the first 1-2 years of its life as it leaves less of a paper trail to follow , i found out i had a clocked car and one of the guys in one of the forums im on i went to a garage to do a full diag for me and look at the true miles the garage owner said to me on the phone that he had the same make of car in his garage and he would use the diag on that to make sure as it had been a bit of time that he had done any diag stuff on that type of car any way he found that was clocked to ,i had phoned about 3 main garage dealers to get a diag and they said the cant be clocked and it was a waste of money yea rite
 
Yves Geza said:
As an aside I'm fascinated by the current fashion for "engine stop start" technology. I wonder how that's going to play in four or five year's time?
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Low displacement volume turbocharged engines is another thing that scares me in ageing cars. Particularly if we look at bigger cars. I am sure the tech will get more stable with time, but the first ones could start failing soon?
 
daugirdas said:
Low displacement volume turbocharged engines is another thing that scares me in ageing cars. Particularly if we look at bigger cars. I am sure the tech will get more stable with time, but the first ones could start failing soon?
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Why does it scare you? Turbos have been around for years, they're not all the same size and are therefore matched to the engines. Not all the extra power comes from the turbo, lots of other components within the engine have changed over the years to release more power, improve fuel consumption and reduce emissions.
 
nilagin said:
Why does it scare you? Turbos have been around for years, they're not all the same size and are therefore matched to the engines. Not all the extra power comes from the turbo, lots of other components within the engine have changed over the years to release more power, improve fuel consumption and reduce emissions.
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No, I am rather concerned that the engines now run close to their theoretical limits and hence could be very worn after some 5 years. For example 1.6 tdi or 1.4tsi vs 2.0tdi (or bigger) in the same car model.

Turbo replacement is just about affordable if the worst happens, but engine is not
 
You may think the engines are running close to their limits, but they are not. Take the Ford 3 cyl 1.0 Ecoboost engine. 100ps in n/a form, 125ps with turbo, the latter is quite safely tuned to 135ps and Ford have had 205ps from the same engine with little more than a larger turbo.
 
terryuk said:
a car 2 -3 years old wont have an mot, easy enough to get done nowadays
i just sold my 2004 cooper s with 46k on it which is 4600 miles a year and had all old mots to verify mileage
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Think my son bought that car! Fantastic Mini!
 
Matts dad then
Loved that mini too shame it just wasn't big enough for us any more
 
nilagin said:
You may think the engines are running close to their limits, but they are not. Take the Ford 3 cyl 1.0 Ecoboost engine. 100ps in n/a form, 125ps with turbo, the latter is quite safely tuned to 135ps and Ford have had 205ps from the same engine with little more than a larger turbo.
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I am sure you can generate even more bhp than Ford demonstrated, but my point is not about it. The engines are working harder and there is more wear over much smaller surface area of moving parts. Will it translate to engines that reach EOL after 5-8 years instead of 20-30? You could see why this would benefit manufacturers. The 1.9TDI or some of Honda engines must have been the biggest headache for the industry as they just keep on going and do not need replacing every 3-4 years.
 
daugirdas said:
I am sure you can generate even more bhp than Ford demonstrated, but my point is not about it. The engines are working harder and there is more wear over much smaller surface area of moving parts. Will it translate to engines that reach EOL after 5-8 years instead of 20-30? You could see why this would benefit manufacturers. The 1.9TDI or some of Honda engines must have been the biggest headache for the industry as they just keep on going and do not need replacing every 3-4 years.
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What engine needs replacing every 3 or 4yrs? Or 5-8yrs for that matter? If the engines are serviced properly with the correct oil, there is no reason for any more wear than you'd find on a larger displacement engine.
As I said before, components within the engine and changes in how fuel is injected etc. have changed over the years enabling the engines to produce more power, work more efficiently and not really having to work harder for it. This has allowed manufacturers to downsize engines, whilst maintaining or increasing the output. You'd be surprised how resilient the engines are. It's just natural progression of engine development, back in the 70's a Ford 2.0 ohc engine was producing 98bhp, 2000 the Ford 1.6 Zetec SE engine produced 90 bhp, now we have a 1.0 engine producing more. Most engines will spend lengthy amounts of time at around 3-3500rpm cruising on motorways, yet when they are being developed could spend a couple of hours (*) at a time on a dyno around 4 times a day (*where half that time will be spent at various rev ranges 3,500rpm through to 6500rpm). Engines are then stripped, and checked for signs of wear as well everything being measured and checked against the measurements obtained when it was first built. If you were to dismantle a modern engine and some of the components you'd see how things have changed and how they can easily produce the levels of power without the engine having to work too hard.
 
I suppose if you were a very high mileage user then you could have your speedo adjusted once a year before MOT time if you realy wanted to maybe a Taxi driver for instance over a period of a few years could buy a nice 3 year old with 25k on it then run it for 3-4 years pile on 100k but prior to each MOT get it tweaked. All servicing carried out locally etc. Come 5 years old its on the market with 40k on it and all paperwork to match.
 
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nilagin said:
You may think the engines are running close to their limits, but they are not. Take the Ford 3 cyl 1.0 Ecoboost engine. 100ps in n/a form, 125ps with turbo, the latter is quite safely tuned to 135ps and Ford have had 205ps from the same engine with little more than a larger turbo.
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almost 100hp/litre from an na engine in a production car is mighty impressive. I'm just thinking about what driving a 100bhp 998cc Imp engine is like - lots of noise, very little low down torque, as the camshaft profile required to make that much power does little below about 3000-3500rpm then it all arrives at once. I guess variable valve timing and electronic engine management help a lot.
 
I only know three things about car engineering. I know when to use tank tape, I know when to use WD40, and I know the roof don't leak when it's not raining! ... If the car ain't fitted with no stop-start technology y'all can't have no problems when that technology goes wrong or wears out!

Daugirdas raises a good point though. If the latest generation of engines, like the 3-cylinder Ford, develop the same BMEP from half the swept bore volume and half the bearing area, the loadings have to be proportionally so much greater!

However for the upcoming generation of second-hand cars, I still wonder about potential longevity problems caused by heat sink and oil breakdown. Back when I had my roll of tank tape and my can of WD40, I engineered some turbocharged racing cars that ran so hot that you could see the shadow of the rotor through the translucent casing. Back then, even using Mobil 1 in the sump, we were very concerned to let the whole gubbins cool down before we switched it off and knew what happened if we didn't. I doubt if many road car owners show the same concern.
 
Buying a used car was always a worry, e.g' 'is the mileage genuine', 'had it ever had a prang', 'how much life left in the clutch and thrust bearing' etc.

Fortunately, I haven't bought a used car since before 1990, when I started buying new cars, and have had a new one every three years since then, so no Mot of course.

However, the service record is stamped by the main dealer at each service, which of course shows the mileage.

With used cars, I would be suspicious of those with really low mileage for its age.

Being retired, I don't drive to work each day, and as such don't do a high mileage. Even so, my car which is now 20 months old, has 22000 miles on the clock. By the time I change it on September 1st, it will probably have around 24000 to 25000 on the clock.

Given that my use is limited to just pleasure and shopping trips etc, I would be very suspicious of a three year old car with say less than 30000 on the clock, unless there was a very good reason for it, that could be verified.

Dave
 
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DaveS2 said:
Even so, my car which is now 20 months old, has 220000 miles on the clock. By the time I change it on September 1st, it will probably have around 24000 to 25000 on the clock.
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You must definitely be clocking your car if it currently has 220,000 miles on it, and when you come to sell it it'll have 24,000!

:banana::D:banana:
 
Ooops!!! :rolleyes:

Yep, you're right :)

I have now duly amended it to read 22000 :)

Dave
 
Yves Geza said:
I only know three things about car engineering. I know when to use tank tape, I know when to use WD40, and I know the roof don't leak when it's not raining! ... If the car ain't fitted with no stop-start technology y'all can't have no problems when that technology goes wrong or wears out!

Daugirdas raises a good point though. If the latest generation of engines, like the 3-cylinder Ford, develop the same BMEP from half the swept bore volume and half the bearing area, the loadings have to be proportionally so much greater!

However for the upcoming generation of second-hand cars, I still wonder about potential longevity problems caused by heat sink and oil breakdown. Back when I had my roll of tank tape and my can of WD40, I engineered some turbocharged racing cars that ran so hot that you could see the shadow of the rotor through the translucent casing. Back then, even using Mobil 1 in the sump, we were very concerned to let the whole gubbins cool down before we switched it off and knew what happened if we didn't. I doubt if many road car owners show the same concern.
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Don't know about other manufacturers but Ford's Stop/start can be switched off and as I said earlier, it doesn't operate anyway until the engine gets up to temperature.
A lot of engines now have oil coolers to look after the oil and keep it in as best possible condition. Most engine oils are now semi or fully synthetic anyway and more capable of doing the job than, say, 20yrs ago.
I've not had the pleasure of properly running a turbo engine on a dyno yet, but the n/a engine I am currently working on does produce a lovely red hot glow on the manifold and cat casing. Watching the computer monitors, it's surprising how quickly the engine and exhaust temperatures do come down again. Cooling systems are a lot more efficient than they once were.
With computer controlled multiple fuel injection, variable valve timing and also spark advance and retardation, the burn process is more controlled and gradual rather than an immediate explosion, this means less shock loading on the moving parts and hence being able to produce larger amounts of power from smaller displacement engines reliably.
 
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Cooling systems can be as efficient as you like but if (as happens) people switch the engine off while the turbo(s) are still close to red hot, the oil that's still in the bearings will break down and carbonise. I'm not sure how long it takes for a turbo to be cooled down after spinning but I always try to approach home downhill on the overrun to give it a bit of a chance and then sit at tickover for a moment or 2 to keep the oil circulating.

IIRC, bike engines (which have been producing 100 BHP/litre at high revs for some time) sometimes use roller mains. This did make it hard for a group of American bikers some years back when they tried to blow up the "Jap cr@p" by stringing it up with the throttle wide open. After some hours they drained the oil but it still went on running for several more hours.
 
Nod said:
Cooling systems can be as efficient as you like but if (as happens) people switch the engine off while the turbo(s) are still close to red hot, the oil that's still in the bearings will break down and carbonise. I'm not sure how long it takes for a turbo to be cooled down after spinning but I always try to approach home downhill on the overrun to give it a bit of a chance and then sit at tickover for a moment or 2 to keep the oil circulating.
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Even at idle, your turbo will be spinning at around 17,000rpm, as I said, even fairly basic engines have oil coolers now, which will be cooling your turbo. Provided you don't rev the engine hard as soon as you start it or just before you switch off, your turbo should be fine.
 
The turbo will be spinning but at low revs it won't be getting red hot. Unfortunately (for the cars but happily for us given global warming and rising sea levels!!!) we live near the top of a steep hill, although mine can climb it in 4th at 30MPH (=1250 RPM). Dropping down the final 1/4 mile o the overrun hopefully allows some cooling time for the turbo even if it is still spinning. Not sure how high I need to rev before turbo 2 kicks in or for turbo 1 to provide effective boost.
 
Chances are your turbo won't get red hot, not unless you're driving around at 4500 rpm in 1st gear all the time. It takes me less than a minute to get home from a dual carriageway, the few seconds it takes me to drive 100yds down my road and park up is more than enough to allow the turbo to cool and switch off.
 
4,500 is close to the redline! VERY rarely use 1st.
 
Nod said:
4,500 is close to the redline! VERY rarely use 1st.
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I guessed it would be. I would assume the highest revs your engine is likely to be held constantly for any length of time would be around 2000, hardly enough to make the turbos hot enough to worry about cooling before stopping the engine.
 
But engine revs alone wont cause the heat buildup. Its under boost conditions that causes the majority of the heat.

And driving at a set revs isn't putting the turbo under much stress at all
 
mattyg said:
But engine revs alone wont cause the heat buildup. Its under boost conditions that causes the majority of the heat.

And driving at a set revs isn't putting the turbo under much stress at all
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Depends on the revs you're driving at. At the higher rev ranges of an engine, the turbo is spinning at over 230,000 rpm. Even under fast acceleration the turbo doesn't stay on boost that long for heat to be anything to worry about. You'll soon be in top gear and the turbo can slow down and cool. The engines on the dynos at work are held at high rpms for a lot longer and sustain the high levels of heat for longer than they are ever likely to once fitted in a car and driven on a road. If a turbo fails, it's investigated and fixed so it won't fail. Failures of turbos in modern road cars are usually down to poor servicing, such as lack of oil changes or using the wrong grade of oil, or the turbine blades getting damaged by foreign bodies entering a poorly filtered induction system.
 
Some of the modern tiny engines seem to have long service intervals. Fiat twin air is 18,000 miles. I'd wonder whether such intervals would increase potential failures especially in low mileage cars.
 
nilagin said:
Depends on the revs you're driving at. At the higher rev ranges of an engine, the turbo is spinning at over 230,000 rpm. Even under fast acceleration the turbo doesn't stay on boost that long for heat to be anything to worry about. You'll soon be in top gear and the turbo can slow down and cool. The engines on the dynos at work are held at high rpms for a lot longer and sustain the high levels of heat for longer than they are ever likely to once fitted in a car and driven on a road. If a turbo fails, it's investigated and fixed so it won't fail. Failures of turbos in modern road cars are usually down to poor servicing, such as lack of oil changes or using the wrong grade of oil, or the turbine blades getting damaged by foreign bodies entering a poorly filtered induction system.
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But turbo heat is NOT just about revs its about production of boost

Sat still on my drive revving the engine to 5000 Rpm wont put the turbo under much strain nor produce much boost on my car less than 5psi However WOT at 2500 rpm will produce 21psi
 
Skoda 1.9 PD130 engine, 130k miles, 100k of those on a remap giving 193bhp and 412ft/lbs torque. Lovely. Car has never had any serious money spent bar a power steering pump at 99k...
 
mattyg said:
But turbo heat is NOT just about revs its about production of boost

Sat still on my drive revving the engine to 5000 Rpm wont put the turbo under much strain nor produce much boost on my car less than 5psi However WOT at 2500 rpm will produce 21psi
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When we run full load curves (WOT) the engine will be running at 1000rpm up to just below the rev limiter for a couple of hours or more several times a day, turbos run just fine. That is just on emissions tests let alone the endurance tests etc that engines have to go through on other dyno tests. The ecu learns at what revs at WOT the exhaust temperatures become too high, it alters the air/fuel ratio and brings the temperatures back down. Reduction of exhaust temperatures, reduces the heat in the turbo. Once off WOT, exhaust temperatures, reduce rapidly. Oil temperatures also drop, cooling as well as lubricating the turbo as well as the induction air also cooling the turbo. As I keep saying modern engines are much more efficient at controlling heat as well as much more efficient at producing bhp and torque than they were years ago. They are not something to be wary or frightened of.
 
nilagin said:
I guessed it would be. I would assume the highest revs your engine is likely to be held constantly for any length of time would be around 2000, hardly enough to make the turbos hot enough to worry about cooling before stopping the engine.
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Motorway speed is at 1750 revs (near enough) so 2000RPM ~ 90MPH. Faster than I really want (or need!) to go most of the time! Coming up the hill on the way home is at about 1250 RPM so probably barely boosting. Then again, coming up the same hill but a different side is through an NSL area and twisty so is usually a bit quicker and playing on the flappy paddles... THAT's when a short cool down period is possibly a good idea. A friend has recently fried the turbo on their AUDI (£1500 bill...) and is also only getting about 35 MPG on a run from a 2l. Glad I went bigger and British (built, if not owned these days!) for economy not to mention style!!!
 
Nod said:
Motorway speed is at 1750 revs (near enough) so 2000RPM ~ 90MPH. Faster than I really want (or need!) to go most of the time! Coming up the hill on the way home is at about 1250 RPM so probably barely boosting. Then again, coming up the same hill but a different side is through an NSL area and twisty so is usually a bit quicker and playing on the flappy paddles... THAT's when a short cool down period is possibly a good idea. A friend has recently fried the turbo on their AUDI (£1500 bill...) and is also only getting about 35 MPG on a run from a 2l. Glad I went bigger and British (built, if not owned these days!) for economy not to mention style!!!
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Just been reading up about your engine, it was as I thought, developed and built by Ford. It is based on the 2.7 V6 TDCi but much improved. Your first turbo works at lower revs, whilst the 2nd turbo starts to kick in at 2800 rpm.
 
Based on verbal comparisons with someone who has the 2.7 version, the 3 is significantly better in every way, from smoother delivery to improved efficiency. For the miles I do, one of the V8s wouldn't be that much more expensive to run but the insurance and tax is a LOT more! Besides, even my lower tuned diesel is capable of twice the motorway limit so who needs more? (Her 4l V8 is only 8mph faster - capped at 155 by the gentlemen's agreement that seem to be ignored these days!)

Not sure what revs are needed in mine to get any boost from either turbo - not convinced I've ever used the second one apart from the very occasional hoofing, certainly not in every day driving!
 
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