97 replies to this topic

[Greg Locock]

So a nautical mile is longer on the equator than it is along latitude 52°N-odd. the one that goes through my house. What about an aircraft flying at 50,000 ft.? That would have to get a tramp on.

No, here's what wiki actually says The nautical mile (symbol M, NM or nmi) is a unit of length that is about one minute of arc of latitude measured along any meridian, or about one minute of arc of longitude at the equator. By international agreement, it is 1,852 metres (approximately 6,076 feet).

[Magoo]

[Kelpiecross]

So a nautical mile is longer on the equator than it is along latitude 52°N-odd. the one that goes through my house. What about an aircraft flying at 50,000 ft.? That would have to get a tramp on.

I think the idea is that the one minute of arc is not measured from your latitude of 52 north across to the axis of rotation of the earth but measured from your location down to the centre of the earth - meaning the the angle is always measured on the earth's diameter - like the equator.

As for the plane at 50,000ft - if you draw a circle about 6 inches in diameter representing the earth with a very fine pencil point - the thickness of the pencil line itself would probably represent a distance of more than 50,000ft - so it would make little difference to the overall idea.

[Tony Matthews]

Flippancy is my - main - downfall. It just strikes me as even more redundant than having metric alongside Imperial, to have different forms of basic unit in Imperial. I'll shut up.

[kikiturbo2]

Another interesting feature of this engine... employs a timing belt but wet, runs in engine oil. No replacement interval.

this is one of the things bugging me about this engine, and some other "modern" designs..

I think we are surely getting to a point where the whole engines will be replaced after 200000 km... if not the whole car..

[Magoo]

this is one of the things bugging me about this engine, and some other "modern" designs..

I think we are surely getting to a point where the whole engines will be replaced after 200000 km... if not the whole car..

Small displacement, high specific output generally means shorter service life. I am told the belt had no trouble getting through the 150,000 mile durability test, but that's not that far anymore.

[pugfan]

Flippancy is my - main - downfall. It just strikes me as even more redundant than having metric alongside Imperial, to have different forms of basic unit in Imperial. I'll shut up.

Maintain the rage, try a unit I unforunately have cause to deal with: Data Miles

[malbear]

I find when I am machining for a mild press fit that it is much better to go with thousandth of an inch than metric 30mm is 1.181"
so I just bore to 1.179". thank god for conversion calipers?
Big end clearences are always given in thous 2 to 2.5 thou

[Lee Nicolle]

I find when I am machining for a mild press fit that it is much better to go with thousandth of an inch than metric 30mm is 1.181"
so I just bore to 1.179". thank god for conversion calipers?
Big end clearences are always given in thous 2 to 2.5 thou

As it seems do most machinists. Most good automotive machinists all seem to be working in imperial,, and conversion charts. Though 1 thou is 1 though if you start in metric or imperial.
Wether it be a slide fit, press fit shrink fit oil clearance, piston clearance. you start with a 101.4 bore and then give it 1 and 1/2 thou clearance !!

[Lee Nicolle]

Small displacement, high specific output generally means shorter service life. I am told the belt had no trouble getting through the 150,000 mile durability test, but that's not that far anymore.

3 year throw away motorcars, they have been around for a good while. Instead of 40 mpg I will take 30 mpg and drive it for 10 years. Hi tech forced aspirated engines will never be a long life proposition. yes they are better,, but the maintenace costs have skyrocketed.

[Tenmantaylor]

3 year throw away motorcars, they have been around for a good while. Instead of 40 mpg I will take 30 mpg and drive it for 10 years. Hi tech forced aspirated engines will never be a long life proposition. yes they are better,, but the maintenace costs have skyrocketed.

Just to play devils advocate; 25% extra fuel costs over 10 years might equal the cost of a new car. Even assuming that fuel costs remain static spending £75 a week on fuel instead of £100 would equate to a £13,000 saving. It'll probably be closer to a £30,000 saving if costs rise as predicted

Edited by Tenmantaylor, 05 December 2012 - 11:59.

[Greg Locock]

I may have missed something, but why do you think a disposable car would have a better fuel consumption? Surely you can afford to spend more on fuel economy bits on a car with a longer life, up to a point?

[Magoo]

This may not be true of the global market but in the USA, I don't know there is such a thing as a three-year disposable car. I think that's more of a function of the owner's service and driving habits than the vehicle itself. Our absolute bottom-feeder new cars in price include the Nissan Versa, Hyundai Accent, Kia Rio, and Ford Fiesta. These vehicles generally will go ten years and 200,000 miles with reasonable care. The question for me is if the I-3 in the Fiesta will hold up as well as the I-4 that is also offered. Ford is confident but I guess we will see.

[Greg Locock]

The 3 year life concept doesn't make sense to me either. In the USA the powertrain HAS to go 100000 miles, so I'd have thought that was the bottom end of a target life.

At the same time, cars with 200000 on the clock aren't that common (cue string of anecdotes that prove nothing), and frankly haven driven a 300000 km Toyota I'm not sure there is much point in beating that as an average.

So far as I know the Japanese are the only nation with an effective 3(?) year rule, and their retired cars are exported all over the place.

[Magoo]

The most common I-3 over here in recent years is the Suzuki Swift/Chevy Geo Metro, which developed a reputation as a bit of a thrasher and/or nickel rocket.

Might not be totally deserved, however. The high-milers (a sort of cult-hobby of fuel economy modders) love them, torture them in all sorts of ways.

[mariner]

I would be surprised if any mfr. designed a car with less than a planned 10 yr life on the major components simply because with 5 year waranties being a marketing tool it would be a warranty cost risk at 5 years on the tail of the 10 yr mean or median distribution.

The average life of cars is tracked carefuly in markets like the US as it impacts replacement sales. For example US car sales at at a 4 yr high now partialy due to deferred replacement during the credit crunch ( buy auto parts stores shares in a recession etc.). I think US average vehicle life is 12 years currently.

I dont know , but I suspect, engine life will have liitle do do with vehicle life. Modern ars are so complex and repair cost per unit is so high versus mfg cost that cars are scrapped like aircraft - can be repaired but uneconomic to do so. Also remember most serious crashes after, say, 4 years old, will write the car off.

[kikiturbo2]

This may not be true of the global market but in the USA, I don't know there is such a thing as a three-year disposable car. I think that's more of a function of the owner's service and driving habits than the vehicle itself. Our absolute bottom-feeder new cars in price include the Nissan Versa, Hyundai Accent, Kia Rio, and Ford Fiesta. These vehicles generally will go ten years and 200,000 miles with reasonable care. The question for me is if the I-3 in the Fiesta will hold up as well as the I-4 that is also offered. Ford is confident but I guess we will see.

I have a "beater" as a wifes daily driver.... it is an old POS Daewoo Kalos (Chevy Kalos for you americans) and it is just approaching the 100000 mile mark... allready having had it's cambelt replaced and it was in a very sorry state at 120000 km...
However... I really do not see it being a disposable item as it will happily do another 50 - 100 thou... So I wonder, what will happen to that ford cambelt at 150000 miles?

[kikiturbo2]

I would be surprised if any mfr. designed a car with less than a planned 10 yr life on the major components simply because with 5 year waranties being a marketing tool it would be a warranty cost risk at 5 years on the tail of the 10 yr mean or median distribution.

Warranties are a money maker... esp. the long ones.. On one hands you have a "safety net" of a 5 or even 7 yr warranty (KIA offers 7 year warranty on some models over here) but you have to do all servicing at an approved dealer.. Now, oil changes are OK, but once you start into brake and belt changes, it soon becomes expensive.. And they tend to change things on a regular bassis..

On the other hand.. In markets that are hit by recession... we see people opting for longer and longer credits... 7yr car loans are quite normal over here..

[Greg Locock]

http://www.thetrutha...s-fingers-ford/

There are some intelligent comments there, and some silliness. Obvious thing to do is to take one of the CR cars into an impartial lab and get them to run the EPA tests on it.

We have one of the one litre Ecoboost Fiestas here as a run about and it doesn't hit the claimed figures, but it doesn't get driven like a test cycle. It does get 60 mpUSg on any serious journey, at which point you really do stop caring.

[mariner]

Kikki, I think you are in Norway which is not in the EU so what you say about using an approved dealer may be true in Norway but its not true under EU law.

In one of the few sensible things the EU have done recently a law was created which means as long as you use OEM parts you can service the car anywhere without voiding the mfr. warranty.

I dont know about the rest of the world but I wouldnt be surprised if similar rules have been created.

[Lee Nicolle]

The cheapy so called fuel efficient cars are often very expensive for parts. Or parts ar non existent after a fairly short time. The engines will go longer than that ofcourse, actually fairly reliable. BUT simple things like a set of belts and radiator hoses for instance. Now Mondeos, Fiestas, Focuses Astras and Vectras along with i am sure many others have a multi branch bottom hose, something like 7 branches. To do the job with parts is at least $500. Genuine only ofcourse. Old Mondeos it now literally writes them off. Yet those engines IF serviced properly outlast all that stuff and go quite well. Just to get at the filter is remove a plastic cover under the car, held on with both self tappers in sheetmetal and those bloody awful scrivets.
To do servicing on any modern car you need a hoist and ever increasing amounts of tools. Ford use different hex bits for multiple items, another $100 or two just to buy the bits to do simple jobs that a normal bolt would have sufficed on.
Look at most 3 y/o old cars,, of any creed. The polycarb headlights are going opaque. $3-500 ea [often far more]genuine, half aftermarket if you can get them. And a roadworthy item.Wheras a glass round headlight goes for 40 years and costs $100 new,, of $35 aftermarket.A 13k car with a $1000 worth of headlights.
Dealer servicing for the extended warrantys is a con. In Oz it has been outlawed as far as i know.One of the franchise chains challenged it in the high court. Scheduled servicing however must be carried out which is fair enough.
Though finding the expertise is sometimes getting harder and harder, especially in sparsley populated areas. Country mechanics have a dozen cars sitting in the sun waiting on parts. Just like the motorcycle trade. My brother stores up to 20 bikes at any time waiting on parts from Japan,,, or other overseas locations. That is when you need a spare vehicle. Like an old 70s Ford or Holden that the mechanic can patch up and keep going. Simple, tough and reliable. Ugly, uncomfortable drafty notwithstanding!
So 3 year throwaway cars are here,, and have been for quite a while.

Someone mentioned a Daepoo Chaos, dreadful car but actually reasonably cheap to maintain, but very few left. All scrapped for the above reasons. Though dont expect to buy front shocks in this country, inserts, genuine only are over $700 trade and I bought the last ones in Oz last year.

so dont go ooh aah about this crap. Think about maintenance costs, as well ofcourse as crash costs. Especially the raft of odd bods being hoisted on the unmsuspecting market. Gone next year along with the parts back up often too.Your 15-20k oo aah eco box os worth nothing!!

[kikiturbo2]

Kikki, I think you are in Norway which is not in the EU so what you say about using an approved dealer may be true in Norway but its not true under EU law.

In one of the few sensible things the EU have done recently a law was created which means as long as you use OEM parts you can service the car anywhere without voiding the mfr. warranty.

I dont know about the rest of the world but I wouldnt be surprised if similar rules have been created.

I am in Croatia, but for the rest you are 100% correct... We are not in the EU yet and you HAVE to go to the official dealer to do the servicing otherwise it is good bye to warranty...

[kikiturbo2]

Or parts ar non existent after a fairly short time.

How about parts are non existant period. I am doing quite well this year, producing spare parts for a small hydraulic pump installed in some mitsubishi EVO's.... All pumps fail due to corrosion, and Mitsubishi will not provide spare parts... just whole pump assembly, @ 3000-4000 USD a pop...

[MatsNorway]

Kikki, I think you are in Norway which is not in the EU so what you say about using an approved dealer may be true in Norway but its not true under EU law.

In one of the few sensible things the EU have done recently a law was created which means as long as you use OEM parts you can service the car anywhere without voiding the mfr. warranty.

Norway are following at least some of the EU made rules on the car side. EU control every 2nd year being one of them.

[Magoo]

How about parts are non existant period. I am doing quite well this year, producing spare parts for a small hydraulic pump installed in some mitsubishi EVO's.... All pumps fail due to corrosion, and Mitsubishi will not provide spare parts... just whole pump assembly, @ 3000-4000 USD a pop...

Right, the good old "aftermarket solution." Behind every one, there's generally someone making a nice pile of $$$.

[Lee Nicolle]

So many assemblys around that you cannot service, just buy a replacement assembly for big dollars. Generally they would repairable if parts were advailable. They are made, to make the new ones!
Though nothing new, a lot of older cars with power windows strip the nylon crown wheel in the gearbox on the motor. But it is not serviced, buy a complete assembly. Though these days you cannot ofcourse. Prop the window up with a piece of wood. That is the reason I do not buy collectables with power windows. Though some manufacturers should not be allowed to sell cars with power windows, they are always going wrong. Crook regulators, switches, wiring harnesses. And just bad design to start with as they try and wind up sideways with no adjustment to correct it. Grrrrr!!

[Tenmantaylor]

Manufacturers care more about being able to build cars quickly and cost effectively than the ability for an end user to service the car quickly and cheaply. This is the main reason new cars are more difficult and expensive to service, not that manufacturers don't want cars to last. Everything has a life but making parts easier and cheaper to replace would mean making the purchase price of the car higher. How many people are wiling to pay extra to make it cheaper to fix when it breaks? You don't buy a new car planning on it breaking.

Sub assemblies are a good example of this. Manufacturers don't buy or stock those simple individual components you talk about, the tier 3,2,1 suppliers do so the manufacturer can reduce stock levels are SKU codes which have a direct link to cost and assembly time which are huge overheads for manufacturers.

If you look at the design complexity of a modern cheap car compared to expensive old car it is quite unbelievable how they are made for the purchase cost. This is only possible due to complex sub assemblies which are designed and supplied out of house.

Edited by Tenmantaylor, 09 December 2012 - 17:55.

[Greg Locock]

What a lot of people don't understand is that new cars are not sold to enthusiasts, tinkerers or home mechanics. New cars are sold to the people who buy new cars. About 60 % of them are interested in Total Cost of Ownership, as defined by themselves. I imagine that the replacement cost for power windows is fairly low down in their list of priorities, since if it is nearly new it is fixed under the warranty, and if it is not then there is only a small window (ha) of risk before it is sold to the next buyer. That bathtub curve of reliability still holds true.

[Canuck]

Agree. I count myself lucky that at least one of my vehicles was, at some point in it's history, a popular model. There are almost always several of fresh units at the wreckers when I'm out scavenging for whatever's failed now. The cost of new replacement parts is obscene but then it's 20 years old - that there are new parts is remarkable.

I feel as though all of existence is shifting gears and moving at a steady frenetic pace. Your 15 minutes of fame now really are 15 minutes, give or take some end-of-the-curve YouTube hits. News? Today, maybe tomorrow, a week if it's big and on-going. I am bombarded with and stumble over so much personally interesting or relevant information in a day, I can't keep track of it much less absorb it.

Bathtub curve?

[Greg Locock]

Bathtub curve?

http://en.wikipedia....i/Bathtub_curve

That's why you fix your 1-2 faults in the first year of ownership, and then have 4 years where routine service is sufficient.

[Rasputin]

http://en.wikipedia....i/Bathtub_curve

That's why you fix your 1-2 faults in the first year of ownership, and then have 4 years where routine service is sufficient.

Giggles...there's hardly anything in this world more misunderstood than the "bathtub curve", but let's not get too engineerish.

[Magoo]

Giggles...there's hardly anything in this world more misunderstood than the "bathtub curve", but let's not get too engineerish.

Why not? That's what we do here. Grab your funny hat and oil can and let's do some engineering. I have some thoughts on the matter myself.

[J. Edlund]

Manufacturers care more about being able to build cars quickly and cost effectively than the ability for an end user to service the car quickly and cheaply. This is the main reason new cars are more difficult and expensive to service, not that manufacturers don't want cars to last. Everything has a life but making parts easier and cheaper to replace would mean making the purchase price of the car higher. How many people are wiling to pay extra to make it cheaper to fix when it breaks? You don't buy a new car planning on it breaking.

Sub assemblies are a good example of this. Manufacturers don't buy or stock those simple individual components you talk about, the tier 3,2,1 suppliers do so the manufacturer can reduce stock levels are SKU codes which have a direct link to cost and assembly time which are huge overheads for manufacturers.

If you look at the design complexity of a modern cheap car compared to expensive old car it is quite unbelievable how they are made for the purchase cost. This is only possible due to complex sub assemblies which are designed and supplied out of house.

I don't think new cars are that difficult to service, if you count service hours per distance driven I would suspect you spend less time on service today than in the past. But one significant difference between service and manufacturing new cars is that the latter is a highly automated process, service on the other hand is mostly slow manual labor. Since the costs of wages have increased as the GDP/capita increases one could really expect the cost of service to increase compared to the cost of a new car.

It's true though that the manufacturers usually stock complete subassemblies as received from their suppliers, this sometimes make replacement parts really expensive.

[Lee Nicolle]

Since most of my mechanical work these days is servicing they are more complex and more expensive to service, though time wise not disimilar. Far less spark plugs and no points. BUT when you do they are expensive.Like $30-$35 ea retail. Airfilters in plastic boxes that break, the clips fall off, screws strip out are just a consumeable, as are often air flow meters, oxygen sensors and the like. And often a visit from the auto elec to make everything talk to the computer again. Or cleaning dirty connections. There is far more things to go wrong, far more plastic parts with again about a 3 year service life. And ofcourse coolants while not expensive are far more critical these days as are lubricants. And oh so often you have to drop the splash tray underneath just to get at the filter. With all the scrivets and poor quality fasteners. They often end up zip tied, wired etc on. this on low KM comparitivly new cars. brakes these days is often rotors as often as pads, and some are far better than others. Meanwhile my 150000mile 40 year old Ford Galaxie still has the original unmachined rotors. And the original though patched a couple of times radiator. Something that again is really a 3 year item on modern cars. And modern cars are coroding out the trans cooler lines and filling the transmission full of coolant. $2000 job on sometimes 2 year old cars.The trans has to be removed and cleaned out as too the converter. And if the coolant has been there too long it stuffs the tranny too. Fords are very bad for it, as are VE Commodores but I have heard of it on Euro and Jap makes too. And the cheap eco box nastys too!
If you do not clean the trans out it will shorten its life a lot, and sometimes they never work as well after. And most modern stuff uses quite expensive trans fluid too. Dexron is just about obsolete in cars after about 2000.
Never let anyone say modern cars are cheap to service, they are not, and often the so called econo boxes are the dearest. European are generally far worse than Japanese, Australian etc,, and are often far less thought out in relation of servicing. Making it dearer.
And for the home handyman, really you need a hoist just to get at most things, Very hard doing it on stands or ramps. I am too bloody old to even try!!

[NeilR]

I don't think new cars are that difficult to service, if you count service hours per distance driven I would suspect you spend less time on service today than in the past. But one significant difference between service and manufacturing new cars is that the latter is a highly automated process, service on the other hand is mostly slow manual labor. Since the costs of wages have increased as the GDP/capita increases one could really expect the cost of service to increase compared to the cost of a new car.

It's true though that the manufacturers usually stock complete subassemblies as received from their suppliers, this sometimes make replacement parts really expensive.

I agree on the labour vs assembly aspect, but I also feel that it depends very much on the car and the service required:
A friend is replacing the timing chains on a modern Jeep grand cherokee, will be a $4500 job at the end of it all. An air conditioning rebuild on a 750il BMW was eye wateringly expensive, but our Toyota Tarago is as easy as it gets.
In comparison I had the misfortune to replace the head gasket on a 1997 T4 VW - lots more work than anticipated and $500 in parts in addition to the $500 head recondition. I do have to say this; after working on the VW...Toyota really know their stuff! All the sharp corners in the engine bay scratch and slice me well! Also, while I am ranting...who the hell at VW thought that the harmonic damper pulley needed 460nm to lock it on there?

[Magoo]

The old ones are far, far easier and more pleasant and satisfying overall to work on, no question about that.

[mariner]

Giggles...there's hardly anything in this world more misunderstood than the "bathtub curve", but let's not get too engineerish.

Long ago I worked ( as a beancounter) for a large US office equipment company which accepted the "bathtub" curve as gospel. So when they launched a product they accepted some infant mortality failures as normal. They would then estimate the eventual product reliability by projecting down the first half of the bathtub curve.

That worked fine until the Japanese competition came along and was put on competititve test. Utter Panic! The japanese machines were far more reliable straight from the factory. The immediate conclusion was that they must be far more reliable at maturity once you adjusted out the infant mortality failues that everybody "knew" existed via the bathtube curve.

So the assumption was that the Japanese machines were not only cheaper to make but more reliable too - implication , huge problems.

In fact, good though the Japanses machines were, the better test reliablity was mainly due to better QC eliminating the infant mortality. So the problems, though large , were not about design reliablity but more about mfg skills.

So beware the bathtub curve !

[BRG]

The old ones are far, far easier and more pleasant and satisfying overall to work on, no question about that.

Just as well, considering how unreliable they were compared to modern designs.

[Magoo]

Just as well, considering how unreliable they were compared to modern designs.

Exactly. It's a good thing we have the new ones to chase parts and supplies for the old ones.

[Magoo]

Long ago I worked ( as a beancounter) for a large US office equipment company which accepted the "bathtub" curve as gospel. So when they launched a product they accepted some infant mortality failures as normal. They would then estimate the eventual product reliability by projecting down the first half of the bathtub curve.

That worked fine until the Japanese competition came along and was put on competititve test. Utter Panic! The japanese machines were far more reliable straight from the factory. The immediate conclusion was that they must be far more reliable at maturity once you adjusted out the infant mortality failues that everybody "knew" existed via the bathtube curve.

So the assumption was that the Japanese machines were not only cheaper to make but more reliable too - implication , huge problems.

In fact, good though the Japanses machines were, the better test reliablity was mainly due to better QC eliminating the infant mortality. So the problems, though large , were not about design reliablity but more about mfg skills.

So beware the bathtub curve !

Generally, any system designed to quantify and manage product failures can also be used to accept, rationalize, institutionalize, and enshrine them. A bathtub curve itself is rather trivial information once you look at it. Consumer products will invariably tend to have bathtub failure curves regardless of their actual failure rates.

An obvious exception is the utterly useless product from the five and dime that breaks in half the first time it is used and is then thrown away. Another exception is the product with zero defects and failures. The pet rock.

I know I have bored the forum with this blabbering before, but the only rigorous defect/failure objective is zero. In manufacturing, any pattern of failure discernible enough to call a pattern has incredible potential for disaster. By the time the pattern becomes clear, the failure could be already out of control. The notable property of mass production is not variety; it's uniformity. Any maximum failure rate above zero will tend to be exceeded, becoming tomorrow's minimum failure rate.

[J. Edlund]

I agree on the labour vs assembly aspect, but I also feel that it depends very much on the car and the service required:
A friend is replacing the timing chains on a modern Jeep grand cherokee, will be a $4500 job at the end of it all. An air conditioning rebuild on a 750il BMW was eye wateringly expensive, but our Toyota Tarago is as easy as it gets.
In comparison I had the misfortune to replace the head gasket on a 1997 T4 VW - lots more work than anticipated and $500 in parts in addition to the $500 head recondition. I do have to say this; after working on the VW...Toyota really know their stuff! All the sharp corners in the engine bay scratch and slice me well! Also, while I am ranting...who the hell at VW thought that the harmonic damper pulley needed 460nm to lock it on there?

Timing chains isn't a part that you normally replace during service. Of course, sometimes they still wear out and need replacement. This is particularly the case when the oil isn't changed according to the manufacturers recommendations, or if the car has run with a low oil level for an extended period. Since these parts aren't intended to be replaced during normal service they can be a bit difficult to replace, in many cases you have to take the engine out of the car which of course is time consuming for the mechanic doing the job. Many engines also got more than one timing chain, two or three is common, and then you typically need to replace the chain wheels and guides which adds to the expense. So if you're unfortunate enough to need a timing chain replacement they can be quite expensive. But on the other hand, most people never need to replace their timing chains.

Newer BMW 7-series tend to use Denso air conditioning compressors, just like Toyota often do. So it shouldn't be more expensive to rebuild than many other ac compressors. There are of course a few different designs and sizes available, like the scroll and fixed and variable displacement swash plate piston pumps, but BMW isn't using anything that is different from what other manufacturers are using.

[Lee Nicolle]

Timing chains isn't a part that you normally replace during service. Of course, sometimes they still wear out and need replacement. This is particularly the case when the oil isn't changed according to the manufacturers recommendations, or if the car has run with a low oil level for an extended period. Since these parts aren't intended to be replaced during normal service they can be a bit difficult to replace, in many cases you have to take the engine out of the car which of course is time consuming for the mechanic doing the job. Many engines also got more than one timing chain, two or three is common, and then you typically need to replace the chain wheels and guides which adds to the expense. So if you're unfortunate enough to need a timing chain replacement they can be quite expensive. But on the other hand, most people never need to replace their timing chains.

Newer BMW 7-series tend to use Denso air conditioning compressors, just like Toyota often do. So it shouldn't be more expensive to rebuild than many other ac compressors. There are of course a few different designs and sizes available, like the scroll and fixed and variable displacement swash plate piston pumps, but BMW isn't using anything that is different from what other manufacturers are using.

I have had this rave before. Timing chains do wear out, and they do cause engine problems even when 'serviceable' as they stretch which throws the cam timing out in turns makes the engine more gutless, thirsty and according to a dyno bloke I was talking too recently often illegal too as the emissions go out the door. Some engines do not get the chain noise, some do but a stretched chain is the biggest performance killer in the automotive world.

For some reason in modern cars Toyota seems to have the least reliable aircond. While not a real issue I have replaced umpteen compressors on Toyotas, far more than any other brand. Though conversly I have never replaced a belt tensioner/idler etc unlike Ford holden, Mitsubishi etc which is fairly common. Though generally a cheaper and simpler job. a lot of pulleys can have a replacement bearing for $5 or $6

Edited by Lee Nicolle, 15 December 2012 - 22:45.

[Canuck]

I have had this rave before. Some engines do not get the chain noise, some do but a stretched chain is the biggest performance killer in the automotive world.

I think that's stretching things a bit...

[kikiturbo2]

BMW/PSA engine of the year, 1.6 turbo had numerous problems with timing chain tensioners for example..

[Tony Matthews]

I think that's stretching things a bit...

Have you got a link for that?

[NeilR]

Newer BMW 7-series tend to use Denso air conditioning compressors, just like Toyota often do. So it shouldn't be more expensive to rebuild than many other ac compressors. There are of course a few different designs and sizes available, like the scroll and fixed and variable displacement swash plate piston pumps, but BMW isn't using anything that is different from what other manufacturers are using.

As with the Jeep the actual part cost is only a small element, though in the older 750il case I believe the steering column, then dash need to be removed to get to the interior AC unit and control unit, then the engine needs to be dropped down to get to the AC compressor etc. then reinstated and all tested. Perhaps one of the joys of a complex car as it ages...

Correction, I have been told it was an 850 and not 750...not sure of engine bay differences.

Edited by NeilR, 17 December 2012 - 04:08.

[Lee Nicolle]

As with the Jeep the actual part cost is only a small element, though in the older 750il case I believe the steering column, then dash need to be removed to get to the interior AC unit and control unit, then the engine needs to be dropped down to get to the AC compressor etc. then reinstated and all tested. Perhaps one of the joys of a complex car as it ages...

Correction, I have been told it was an 850 and not 750...not sure of engine bay differences.

Far too many cars are built like that. And not just newer ones either. 70s Valiants are a MAJOR job to do a heater core yet alone the A/C core on. Officially you are supposed to remove the windscreen! Though a big lever and you can flex the dash far enough to get it out. though the dash generally sqeaks after!
Lots of cars you have to remove console, dash, column etc these days to do what should be fairly minor servicing. $800 trade to change a heater interface module on a BA BF Falcon. The previuos model had a heater tap under the bonnet, about $30 and 10 min the replace. That is progress!
Again my rant on 3 year throw away cars

[Grumbles]

Far too many cars are built like that. And not just newer ones either. 70s Valiants are a MAJOR job to do a heater core yet alone the A/C core on. Officially you are supposed to remove the windscreen! Though a big lever and you can flex the dash far enough to get it out. though the dash generally sqeaks after!
Lots of cars you have to remove console, dash, column etc these days to do what should be fairly minor servicing. $800 trade to change a heater interface module on a BA BF Falcon. The previuos model had a heater tap under the bonnet, about $30 and 10 min the replace. That is progress!
Again my rant on 3 year throw away cars

While what you are saying may be perfectly true Lee, the flip side is that many modern cars can go a long, long time without needing anything other than routine services. Looking back over the new cars I've had over the last say 15 years - all of them Japanese - none have needed any more than tyres and oil changes. On the other hand I also have a couple of old Holdens that are an absolute pleasure to work on. Which is just as well as they require so much more frequent attention to the niggly little faults that develop from day to day.