I have always been an advocate of the "bangernomics" school of thought, having previously owned a string of old crates that have (more or less) got me from A to B)
My latest car, a 1995 306 1.9 xrdt has proven itself to be a little gem. It has never missed a beat in the three years I have had it, and I would like to keep it running as long as possible. My only concern though is the drivers airbag.
How long is the life expectancy of these things? When do they need servicing or replacing, and what are the chances of an old one simply deploying at random?
Any help would be much appreciated.
Edited by craneboy on 25/06/2008 at 23:11
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As I understand it airbags fail 'safe' in that rather than going off at random they don't go off at all. ISTR bell boy (of sainted memory) used to let off a few scrap airbags in his workshop when bored and none of them failed to fire despite their age.
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I would not think a failed airbag will deploy at random - it probably will not deploy at all when needed.
When my W reg Passat had an airbag problem the garage tried to assure me it won't go off by mistake when the warning light was on because they were all disabled. So all airbags for driver, passenger, side airbags etc. were no use... but were part of the reason for choosing the car!
I think things like old airbags needing replacing might send many cars to the crusher. As will many other things like problems with emissions.
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I wouldn't trust one beyond ten years. Vote 'em out, I say.
Oh, sorry, AIRbags - I was looking for the WINDbags blog...
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Presumably, for an airbag to 'fire' it simply needs a signal to go to its detonator - why anyone would think that's fail safe eludes me. They still find WW11 muntions perfectly capable of fullfilling their 'mission' after 60 years. The question is - how do we know that airbags don't or haven't already gone off for reasons of age/deteroiration/malfunction & how many unexplained one vehicle accidents may have been caused this way?
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Tests on really old ones were run on a TV show, and they were all found to be fine, these were circa 20 years old.
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Some of the suggestions given here on whether old airbags will still 'go off' are over simplistic. Just because the munitions element is still capable of going bang does not mean the installation is capable of fulfilling its primary purpose of going bang 'correctly' at the correct time.
For it to function correctly,
1 the sensing element (ie a decelerometer) has to function correctly
2 the trigger signal must be processed (to ensure correct air bags will be triggered)
3 the trigger signal must be passed to to the detonator
4 the detonator must fire
5 the 'explosion' must occur with the correct 'profile'
6 the bag must inflate and deflate correctly without 'splitting' at the wrong time
I do not pretend that this is a comprehensive list, just my view on how the sytem must function. I am sure that somebody will compile a better description if they work in this field.
Certain of these elements can be checked from static start up tests, which, if failed, will result in the airbag being disabled and the warning bulb being displayed. (Another potential point of failure? if the warning bulb is defective, does the 'smart' electronics disable the system?)
OK this does not answer the original question, merely adds more questions! However would you prefer to have an old car with airbags fitted or one without? On an old car are you 'better off' spending your money on replacing the airbags or spending the same money on premium tyres, better suspension and brake components, or even better headlights, new windscreen and wipers? All of which may give you the edge in not coming to an unexpected stationary state.
pmh
Edited by pmh on 26/06/2008 at 08:00
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Some manufacturers recommend replacing airbags when 10-15 years old. I can't see this happening. My car is about 8 years old and I have no intention of replacing its 4 airbags as it ages.
Old cars are typically less safe than new cars - I'd agree with pmh: spend the money on quality maintenance. I would pay to fix any known faults in the airbag / seatbelt pre-tensioner system.
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This is something I wondered with my Rover as it is now 10 years old. Aparently Rover altered the date to 15 years from 2000ish using the same system as there was no deteriation.
A helpful chap on mg-rover.org who was part of engineering at Longbridge has mentioned that the airbag manufacturers recommend replacement in hot and humid countries at 10-15 years and with our climate lifespan will be considerably higher. Obviously manufacturers dont know where their cars will end up and hence giving minimum life expectancy of the airbag.
Makes sense and good enough for me! Also ties in with whats mentioned above where 20yr old + are working fine!
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I realise this is an old thread but it is still a relevant issue. There is surprisingly little concrete information on this subject. Nothing that I could find on the official Mercedes website.
After much Googling I found this Mercedes service bulletin which has been posted on a forum:
http://www.2phast.com/500e/techdocs/airbaglifespan.pdf
SI91.60-P-0001B
Service Information on airbag units
Dated 9.4.02
MODELS 107, 123, 124, 126, 129, 140, 163, 168, 170, 201, 202, 203, 208, 210, 211, 215, 220, 230, 461, 463
with airbag.
Airbags, that were installed in Mercedes-Benz passenger vehicles up
to January 1992 have a service life of 15 years. After this service life
has elapsed, the airbags must be replaced at the customer's cost. The
service life is evident from a sticker that is either on the
B pillar (driver's side) or on the inside of the vehicle's glove
compartment lid. New airbag technology has made lifelong functional
reliability possible, which means that the airbag service life restriction
no longer applies.
Edited for formatting.
Formatting still not too good. Sorry.
Edited by Billy Whizz on 03/04/2011 at 16:58
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