Electrickery vs Mechanical Failure





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  1. #1
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    Default Electrickery vs Mechanical Failure

    Over the past few weeks I have noticed numerous posts regarding electrickery related problems experienced by the members and perhaps my knowledge of Reliability Centered Maintenance, Preventative Maintenance, Predictive Maintenance, Root Cause Analysis, Failure Mode Analysis etc may be of help.

    Mechanical Failures:

    These are generally gradual and can be detected by sound, smell, sight and touch. There are 4 main causes of mechanical failure, namely:

    1. Poorly manufactured part
    2. Poor fitment of a part
    3. Wear and Tear (lack of lubrication, poor lubricant quality, degradation of lubricant)
    4. Abuse/Mis-use ( when a part or system of parts is subject to an environment, operation and or condition that exceeds its design specification) A crash would fall into this category

    It is interesting to note that in point 3 above, lubrication prevents metal to metal contact and hence wear. Theoretically, no wear can take place if the lubrication specification is maintained. Mechanical failures are rarely "Instantaneous" failures and will, in the main, give some indication that a failure will take place. The question in detecting these, as per MSG 3 (NASA/Boeing) is, are these detectable by the operator of the equipment, hence various gauges being provided (Oil pressure, temp etc). In Aircraft, these have redundent systems so in order to give pilots a level of faith in their instruments. In our instance, we are only given one system.

    Electrical Failures:

    Electronic components are subject to Instantaneous Failure without warning and may not give any warning. Electrical components (wires, connectors, switches etc) can be intermittent (loose connection connecting and disconnecting during driving for instance). These can be either instantaneous or intermittent or intermittent then complete.

    Electronic failures are difficult to determine due to the nature of the electronic circuitry. Electrical are more easily detected using a circuit tester. As these are generally a circuit or closed loop, a methodical approach to testing the resistance in a circuit will eventually lead to the circuit problem (loose connection, broken wire or a faulty component like a switch.

    It stands to reason then that mechanical failure can be prevented by using good parts, fitting them correctly, frequent oil changes and not hitting them with a hammer ala Clarkson. These generally constitute a maintenance schedule.

    Electrical components are generally non-maintainable unless they are replaced at a regular intervals, a costly exercise indeed. Mechanical components (poor part and or poor fitment) can have an "Instantaneous" failure in terms of use, not withstanding the above.

    You may have noticed that aircraft use a steep takeoff angle to gain altitude as quickly as possible. The main reason for this is statistically, if a poor part or poor fitment of a part were to cause failure, it will happen during the stress of take off. Therefore, the more altitude you have, the greater the chance of landing again On this note, most aircrashes take place in flight or close to landing and are generally caused by CFIT or controlled Flight Into Terrain, generally due to the loose nut behind the joystick. The failure of a component on take of will give an indication of failure before it does fail, however, the failure period is accelerated due to the stresses involved that it would be deemed as "Instantaneous".

    The modern method of electric over mechanical systems in vehicles makes the "Potential to Fail" higher in some instances and I personnally try and steer clear of these if possible. A good example of this was the P38 suspension. An electrical fault could render a perfectly useable mechanical component useless. Any one who has driven on the bump stops will agree that this is not a happy situation. While the wear in the suspension could be detected before failure, the electronic component could not.

    While this is a long post, I hope this may be of some use to the members.

  2. #2
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    Default

    Thank yoy Estee. I, for one, am wizer now.

    Reading your post, an owner buying a vehicle run by electrics, planning to keep it for a long time, and do repair& maintenance himself, should invest in a diagnostic tool.

    As far as I can gather most of these vehicles do have a diagnostic circuit that can troubleshoot the fault. Is it true? Would any electric fault be tracable? (for instance the P38 suspention fault)
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  3. #3
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    Default Failures

    Hi,

    Strangely enough electronic circuits can be made to be ultra-ultra reliable.

    Aerospace systems use circuits with generous amounts of overdesign, protection, radiation hardening and laser welded sealed enclosures. Rugged and reliable interconnect systems. Dual or even quad redundancy.

    Consumer electronics in modern cars are not built to these standards - but they are not far off.

    Most electrical failures are in fact mechanical failures - or put differently mechanical failure of an electrical part. In the case of the P38 air suspension, usually things like solenoids, compressor pumps or sensors.

    The poor old P38 air suspension computer has the intelligence of an ant, and in an attempt to protect itself from mechanical failure it does some really stupid things. (Bumpstops being just one of them) However the system is now 10-15 years old and is not a good example to be used as a yardstick for any Mech vss Electical failure debate.

    I have a P38, complete with problems and the obligatory diagnostics computer. I also have 4 other cars, with a gazzilion computers between them without a single electronic problem.

    Whenever I see a review or a post that slates a vehicle because it has "too much fancy electronics", I see RED. There are very few cars nowadays without any electronics, and they are utra reliable.

    While offroading you are much more likely to -

    Have a few flat tyres, loose a fanbelt/waterpump/fuelpump/steeringpump.
    Break a gearbox or a diff or a shock or a spring or a cam or a crank or a piston/piston ring.

    Loose a wheelbearing or diff bearing or a crank end bearing or a bigend/smallend bearing.

    All assuming that you dont have a failure from dirty fuel or a leaking radiator or a holed sump/diff

    Not to mention one of the dozens of seals on the car - brakes, engines etc

    As apposed to an ABS, Gearbox or Engine Management computer malfunction, which all have limp home bypass systems anyhow.

    Either way with many of the above failures you are in the dwang.

    Without the electronics we wouldnt have the performance and the reliability that we have come to expect.

    Cheers
    Fluffy

    PS - I guess it shows that I make a living from electronics

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    Hi Fluffy/Estee,

    What you are saying is true, unfortunately the electronis in the newer cars are very expensive to replace. My platkar is a E240 Merc and is is in for electronic repairs for the 2nd time now in less that 6 months. It is outside its maintenance plan but with less than 120 000 km on the clock?? The repair bills are astronomical as you can imagine. The one that needs to be replaced this time is not even available in the country and needs to be imported from Germany?? I feel thus that it is not common for this piece of electronics to fail, yet I am the person who must pay up?? While the electronics are working, they are fantastic, but beware of the pay day!!!
    Last edited by fanie1; 2010/03/30 at 12:26 PM.

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    Default Gas

    Quote Originally Posted by fanie1 View Post
    Hi Fluffy/Estee,

    What you are saying is true, unfortunately the electronis in the newer cars are very expensive to replace. My platkar is a E240 Merc and is is in for electronic repairs for the 2nd time now in less that 6 months. It is outside its maintenance plan but with less than 120 000 km on the clock?? The repair bills are astronomical as you can imagine. The one that needs to be replaced this time is not even available in the country and needs to be imported from Germany?? I feel thus that it is not common for this piece of electronics to fail, yet I am the person who must pay up?? While the electronics are working, they are fantastic, but beware of the pay day!!!
    Hi,

    True, but think of it this way. It's a baloon payment for the fun you have had so far.

    Without those little computers your E240 would be a big heavy E series Merc with a puny little 2.4 gas guzzling motorcar with shitty brakes and an aircon that operates off little cables and levers that are forever stuck or broken. It may just have been strong enough to pull the skin off a rice pudding.

    Kinda like an insurance policy that you pay for after you have used it.

    What makes your situation worse is that we get ripped of for these spares, often unneccesarily because the mechanic misdiagnoses or breaks something.

    Cheers
    Fluffy
    Last edited by Fluffy; 2010/03/30 at 12:53 PM.

  6. #6
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    Default

    Very true in the above, the electronics of modern cars are extremely reliable. The main point of my post is that mechanical problems can be detected before failure, simple electric circuitry will possibly give some indication of a problem which is relatively easy to trace and fix but electronics will fail instantaneously and without warning. Reliability aside and in the context of the posts, an intermittent oil pressure warning light is probably an indication of a loose or poor connection, relatively simple to diagnose. In the middle of the bush, a fail to safe bump stop (P38 ) due to an electronic fault, would be more difficult to diagnose and repair.

    As a personal preference, I prefer a simple mechanical and or electric system. While I appreciate the drive for electronics to improve performance and consumption etc, until a vehicle is fitted with redundent systems ala aircraft, the "Potential to Fail" still exists with whatever consequences that that entails.

  7. #7
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    Default Mission critical

    Quote Originally Posted by Estee View Post
    Very true in the above, the electronics of modern cars are extremely reliable. The main point of my post is that mechanical problems can be detected before failure, simple electric circuitry will possibly give some indication of a problem which is relatively easy to trace and fix but electronics will fail instantaneously and without warning. Reliability aside and in the context of the posts, an intermittent oil pressure warning light is probably an indication of a loose or poor connection, relatively simple to diagnose. In the middle of the bush, a fail to safe bump stop (P38 ) due to an electronic fault, would be more difficult to diagnose and repair.

    As a personal preference, I prefer a simple mechanical and or electric system. While I appreciate the drive for electronics to improve performance and consumption etc, until a vehicle is fitted with redundent systems ala aircraft, the "Potential to Fail" still exists with whatever consequences that that entails.

    Hi,

    Quite so. In my post I said that newer vehicle systems are approaching Aerospace standards.

    In fact some modern ABS systems actually have a minimum of three computers. Two mission critical hard real-time dual redundant computers and a third computer that manages these two and talks to the rest of the car. Most of the other computers have a limp home mode.

    Once again the P38 is not the best example, but, I would rather limp home on the bumpstops for 200K's then evacuate my family with a heli and send a truck to fetch it in a weeks time.

    Cheers
    Fluffy

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    Default

    Fluffy, I Sir, may not agree with you but will defend to the death, the right for you to air your opinion

    As someone who has used a willow branch instead of an HT lead and cola to repair a slipping clutch, give me the good old distributor, carburettor any day.

    Which leads me to an anecdote regarding the American and Russian space programmes. The Americans spent millions developing a pen for their Astronuts that could write in space, this is the Papermate, the Russians gave their Cosmonuts a pencil

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    Quote Originally Posted by Estee View Post
    You may have noticed that aircraft use a steep takeoff angle to gain altitude as quickly as possible. The main reason for this is statistically, if a poor part or poor fitment of a part were to cause failure, it will happen during the stress of take off. Therefore, the more altitude you have, the greater the chance of landing again
    Not true. All passenger carrying aircraft must be able to have a engine failure on the runway, and if above your accelerate go speed (V1), accelerate to take off speed (VR) and reach a height of 35 feet at the end of the runway at the engine out speed (V2). If you are below V1 you will abort the take off. These speeds vary with weight and runway length etc.

    A twin engine aircraft lose 50% of its thrust with a engine failure, therefore on a take off with both engines running you will have excess thrust and hence the steep climb out. As a matter of intrest, 95% of take offs (Airliner) are at reduced thrust to save the engines. You only use max thrust when you are heavy and on a hot day, espcially at a high altitude airport like Joburg.
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    In a perfect world, electrical components are great and generally very reliable. In my experience, most of the hassles I've had with electrics have either been as a result of my own stupidity or the stupidity of others.

    I commented on a different post how I will not have any tracking system that is wired into the harness fitted on any of our cars, it is for this exact reason.

  11. #11
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    Default Redundant

    Hi,

    Whatever you view, this post has the inbuilt feature of making the debate meaningless.

    Sooner or later we will all be driving cars with lots more electronics than we are happy with. So be it.

    And as technology advances electronics will be the most reliable part of the car.

    But the main criticism still remains valid. If it fails you are in the dwang. Kinda like a pacemaker ? or a crankshaft or .....

    Cheers
    Fluffy

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    Estee,

    I agree with you 100%. I love the ABSENCE of electrics and electronics in older vehicles ( or baseline models....)

    Manual windows, carburettor, "remoteless entry" - known as a key! - all these things last much longer!

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    Default How far back

    Quote Originally Posted by Gert du Preez View Post
    Estee,

    I agree with you 100%. I love the ABSENCE of electrics and electronics in older vehicles ( or baseline models....)

    Manual windows, carburettor, "remoteless entry" - known as a key! - all these things last much longer!
    Hi,

    How far do you want to go back ?

    I cant remember a single Morris Minor trip from Durbs to JHB and back that didnt need a repair or something along the way. I would happily take a Yaris to Cairo and back and not anticipate anything going wrong.

    Manual windows, I remember those, the ones where the cables snap or the gears strip or the winder spline strips. The same ones where the window slowly slides opens by itself as you drive, or doesnt close properly, you need to help it up with your hands.

    Carburettor, I remember those also, The ones where the engine floods on starting (if it starts), where smooth idle is a dream, where you drive with the manual choke ON by mistake, or the idle solenoid goes, or the acceleration pump diaphram perishes. Must be the same ones as the main jets that get blocked and the float sticks. And the vacume advance feed that doesnt work because the distributor is worn. And the mixture is always wrong, so you smell petrol in the car and the fuel consumption and power is prehistoric. Kinda remember spending my beer money on carburettor cleaning fluids and and gasket kits, and spending quality time - Just me and my Webber, Solex, SU, Magneta Morrelli side draughts ( Spelling - ALFA) etc

    "Remoteless Entry" - known as a key! - I will give you this one, but all my central locking cars have a normal key function as a standby.

    BUT - To each his own.

    Gert - a little tongue in cheek, just a nice debate. I do miss spending Sunday afternoons tinkering to see if I can make things better than the manufacturer.



    Cheers
    Fluffy

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    the period of the 50's - 80's (post 2nd world war) a revolution in materials and manufacturing techniques quadrupled mechanical reliability. not in your wildest dreams could you expect a vehicle to cover 100 000 miles without a major overhaul of the engine or gearbox or both. these days you are upset if you can't get at least 300 000km before any significant repairs.

    the 80's through to the present is the electronic age. i remember the first electronic ignitions and fuel injections. everyone was dead against them and everyone predicted 50 000km max before significant failure.

    these days failure of these components in the first 150 000 - 200 000km is almost unheard of. (except for the D4D injectors)

    "infant mortality" is largely eliminated at the factory. more often than not failure can be attributed to outside factors ie oil down the harness, water damage, excessive heat under the bonnet, incorrect procedure when jumpstarting, charging or some other form of abuse.

    with all this considered, electronics are amazingly reliable.

    we, the residents of Africa, are spoilt. the norm in most first world countries is to keep a car a maximum of 5 years or 100 000km. after that the vehicle is recycled.
    if you were to ingore all failures beyond this mileage and redo the calculations, there would be virtually no failures.
    this, compared with cars of 30 years ago, is a ten fold improvement in reliability.

    as they would say at Rolls Royce : breakdowns, what breakdowns?

    Land Rovers never die, they simply become organ donors!

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    One of the main reasons that many people are against electronics, is because they are intimidated by the fact that they don't have the knowhow to fix it. If a window winder packs up, most of us will find a way to "fix" the problem - even if only temporarily. Some of us will even be able to weld broken parts in the bundus, using two or three car batteries. However, very few of us have the knowledge/ ability to diagnose an electrical fault, let alone fix it, and this is a great source of insecurity for many DIY off roaders. They are actually opposing electronics, not because it is not reliable, but because they can't fix it themselves and would therefore rather avoid having it.
    Bite off more than you can chew - then chew!

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    Landyluvver, just as a matter of interest, a Rolls Royce does not breakdown. That is for common vehicle owners like us. For Rolls owners, their vehicles "fail to proceed".
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    Default Like

    Hi,

    I really like this debate. Honestly.

    No ATOYOT vss Rand Lover vss Bitsofshitsu vss Drof.

    Just good technical banter.

    Cheers
    Yffulf

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    Cars in the 50's and 60's would last MUCH longer if they had the benifit of clean fuel, top quality lubricants, good roads.....

    I have driven many cars from "medium" to "high" milage. A couple from new. My 1300 CitiGolf got stolen with almost 200k on the clock, not a single issue. My Honda Ballade had defective electric winders by 50k on the odo. Corsa at 150k has lost Central Locking and Rev counter stopped working and Electronic display (time, outside temp etc) died...

    A simple problem on an "electronic thingamagiggy" can cost thousands. The dreaded "black box" or "computer box" failure. A carb kit costs a few beers, not a few paycheques....

    All these things are OK in a "disposable" asset like a commuter car. The game is different when you talk of serious work / offroad vehicles. A 5% improvement in fuel consumption becomes irrelevant if you burn 50l per 100km in thick sand... But a blocked jet can be solved in the sticks, can you say the same of electronic Fuel Injection?

    Also, GOOD 4x4's are used, sold, used again, sold again, used again....

    Do you think that 50% of Toyota RAV's or Land Rover Freelanders or VW Polos will be with us IN DAYLY USE 30 or 40 years from now?

    Compare with old Cruisers, Landys and Beetles.....

    Gentlemen of the Jury, I rest my case....

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    Quote Originally Posted by Plod View Post
    Landyluvver, just as a matter of interest, a Rolls Royce does not breakdown. That is for common vehicle owners like us. For Rolls owners, their vehicles "fail to proceed".
    they don't proceed, they can't afford the juice! 50l/100km if you drive like a V8 Land Rover owner! that's not a breakdown, it's a nervous breakdown!

    Land Rovers never die, they simply become organ donors!

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    guys, i have come to realise that almost anything is fixable. a recon ECU for R 500 service exchage if you know who to talk to. most electronic are plug and play. you plug a new one in, if it does not play, plug another in.

    HT's messing you around, rip it out and replace with a new set including the ht cap and rotor.
    i believe most of is petrified of electronics but there are a couple of things we all can do. this normally reduced the variables by more than 60%.
    first check all fuses.
    check you battery's voltage and if found under 13 volt, get worried.
    check the camps on the battery to ensure proper contact. follow the earth cable from the battery to the body an check if that is secure. follow the red wire from the battery to the positive connection on the starter and check if clean and on tightly.
    having gone through all of this in 15 minutes, you have narrowed down a lot of potential problems.
    smell for burning, electronic have a distinctive smell when burning. track the source down and inspect.
    as said, this will eliminate 60% of all electrical problems.

    Land Rovers never die, they simply become organ donors!

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