308 Timing Belt Failure Data

Discussion in '308/328' started by tvine, Jul 29, 2006.

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  1. tvine

    tvine Formula Junior

    Jul 19, 2006
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    Tom Vine
    I have been reading for years about the replacement interval of timing belts on 308 series Ferrari engines. The original factory recommendation was every 30,000 miles. I have seen time based recommendations ranging from 3 to 10 years. Being an engineer I have a predisposition toward recommendations based on data. I have searched this and other websites and have not been able to find any failure data on 308 timing belts.

    This is an academic question for me since I have a 1979 308 GTB that has not had its timing belts changed since 1993, 13,000 miles ago. This was only the second time that they were replaced. I intend to replace them VERY soon.

    I understand that these engines are valve crashers, but so are many other high performance engines (and many not so high performance engines for that matter). With factory trained mechanics charging up to $5k for the 30,000 mile service, half the cost of a new engine, this is not a simple “default to the conservative answer” question. A cynic would suspect that this issue is the product of good business development practices by the repair professionals.

    Can any one please point me to any data regarding in-service timing belt failures on 308 series engines? I have already read enough opinions regarding the topic so please only respond with information regarding actual failures.
     
  2. andrewg

    andrewg F1 Rookie
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    On the top left of the page you'll find the word Search, click on it and a box will drop down........enter the following 308 Cam belt + failure followed by pressing the return key

    The simple answer to your question is Belts on the whole fail for one of two reasons, the cars been standing and the belt has weakend in the places it's been sitting or the tensioner bearings have seized, the belts cost $30 and the tensioners $100, whoever's charging you $5000 to change them is riping you off, change to another specialist who's prices are realistic!.......in the UK I charge £280 + taxes (17.5%) to change 308 belts and bearings!
     
  3. sjmst

    sjmst F1 Veteran
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    Jul 31, 2003
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    WOW!! Forget it, can't get it for anywhere NEAR that price here. 3 times that would be considered a bargain in the US.
     
  4. ForzaMaranello

    ForzaMaranello Karting

    Jul 15, 2006
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    [ I have already read enough opinions regarding the topic so please only respond with information regarding actual failures.[/QUOTE]

    I guess then, just drive it until it breaks. Then you will truly know your answer.........
     
  5. andrewg

    andrewg F1 Rookie
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    Thats to change only the belts, a 30k is around 3 times that figure........but still nowhere near $5k!
     
  6. Husker

    Husker F1 World Champ

    Dec 31, 2003
    11,792
    western hemisphere
    Has to be the most re-hashed topic of all time. Simple answer is that a timing belt breaking, ripping, tearing, snapping, "failure", whatever term you want to use - is a rarity.

    I bought a 1982 308 3 years ago that was on its original belts. That's 22+/- years. Does that help you any?

    Besides, in a 308, if a timing belt breaks, you're only toasting HALF of the engine. :)
     
  7. tvine

    tvine Formula Junior

    Jul 19, 2006
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    Tom Vine
    I know that I can buy the parts for under $400. Even if I am really slow and it takes me a week to change them we are not talking about a big deal. Not everyone does there own work out there.

    I know why they break. I also know that $5k for a 30,000 mile maintenance is too high. I am simply trying to assess the correct change interval based on DATA, not opinion.

    Has anyone had one break; if yes what was the age, mileage and other important information such as storage conditions, sitting a long time etc.
     
  8. miketuason

    miketuason F1 World Champ
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    Wow Realy? thats awesom that must be the record.
     
  9. ForzaMaranello

    ForzaMaranello Karting

    Jul 15, 2006
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    I think most of us would not take the chance, why would you want to see how far you can push a timing belt? Why wouldn't you just change it every 5 years and spend the small amount of money instead of taking the chance and having to buy a new set of heads? I think you are not getting you answer because most of us wouldn't take that chance, it's better to be safe than sorry. + they are made of rubber, remember the Firestone issue? Not every tire blew at the same mileage, meaning that one belt may last 15 years and the other 5. Who knows, your question is like asking when is the light bulb in your closet going to go out? You have no clue, it may go out tomorrow or it may last another year. I guess your question makes no sense to me. Why does it matter?
     
  10. gerritv

    gerritv Formula 3

    Jun 18, 2001
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    Tvine, changing only the belts and bearings is 4.6 hours (book time). I can vouch that this is reasonable to do with simple skills.

    The 30k service includes Much more than that. Cam covers off, change cam seals, adjust valves, resync carbs, etc. etc. That takes time. Try working for an hour on the front bank of your engne without taking breaks to unlock your knees. Time = $, depending on the hourly rate it adds up. I understand that there are places in the US charging > $120 per hour so the costs vary. Service times are 19-27 hours + either 4.6 or 6.1 for belt and bearing change depending on presence of A/C. The 19-27 variance depends on Euro vs. US (US is >), pre or post 1997 and FI vs. Carbs.
    Of course surprises and prior neglect or incompetents working on your engine will increase the times and parts costs.
    Take a look at http://dino308gt4.com for the Service Times manual.

    Gerrit
     
  11. tvine

    tvine Formula Junior

    Jul 19, 2006
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    Thanks Garritv. I am not really trying to push it. I have changed belts on cars with much less access that the 308. I will change my belts very soon myself and this is not the issue at all. I was just trying to find out where the facts ended and the possible legend started. It seems that timing belt replacement has become almost a religious dogma in the Ferrari community.

    In a previous position as an Engineering Manager at a commerial nuclar power plant I sponsored a reconstitution of the preventive maintenance program. The purpose was to establish a basis for scheduled maintenance for all 54,000 components in the plant. It was an effort to stop doing maintenance based on opinion and do the maintenance that the facts such as industry failure rates and failure modes analysis. I seem to have struck an emotional chord here. My intent was to remove the emotion and find out what the facts of the issue are.

    My suspicion is that 308s do not suffer timing belt failures at a rate much different than other cars with similar belt set ups. If they do I would like to understand why; greater valve train loads, contamination of the belts, the way the cars are operated?

    Thanks again for your reply.
     
  12. greg328

    greg328 F1 Rookie

    Nov 17, 2003
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    I'd like to know if 308 cam belts (or any cam belts, for that matter) are under more load/tension/stress during hard throttle and/or high RPM.

    Or, are they always at the same tension, regardless of throttle angle/RPM?

    Just wondering if "getting on it" is placing the belts at greater risk.
    I know a minor tear or weak spot would be more apt to fail under these conditions, but I'm wanting to know about healthy, recently changed belts...


    Greg
    77 308
     
  13. gerritv

    gerritv Formula 3

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    Hi Tvine
    My Passat is about to have its timing belts changed at 100k km, the recommended time. So it is definitely possible to have a belt last more than 5 years or 30k km. (My Passat is 2006, not sure if they put a time limit as well as km, will find out soon).
    I replaced my belts after 5 years or was it 6, probably not 30K but close, I drive it a lot and regularly. I do know that the belts looked fine at a glange. But the bearings were 10 years and one was grinding, the other had a tick. So in my case I am glad to have done the bearings (and belts in the process).
    Gerrit
     
  14. Verell

    Verell F1 Veteran
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    May 5, 2001
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    One of the reasons this topic is a sore subject is that to the best of my knowledge, NO COMPREHENSIVE SET OF DATA HAS EVER BEEN AVAILABLE, OR IS EVEN KNOWN TO EXIST. The only place such a set of data might possibly exist is the service and warranty claims records inside of Ferrari & IMHO, getting it out is highly unlikely.

    We're all frustrated by it's lack, As a result there are around 30 cam belt threads in Tech Q&A. Most have a lot of speculation and argument, with a sparse scattering of facts.

    I've been an Fchat member since early '01 & have followed most of these discussions hoping to get enough facts for a good engineering analysis based decision (Yes, I'm an engineer). I've pretty much given up hope of getting enough facts to make an analytical decision.

    Since you've read the archives, you know that there have been a handfull of people brave enough to admit they've had a belt break, and several well regarded professional service technicians who have said that they encounter them more often than you'd like to think. If you haven't done this, take andrewg's advice:

    You should have also seen that there are a couple of threads that asked questions essentially identical to yours.
    One of the longest & most visited was:
    CAMBELT REPLACEMENT EXPOSED
    http://ferrarichat.com/forum/showthread.php?t=64504

    Here's another notable one.
    Who's had their belt break?
    http://ferrarichat.com/forum/showthread.php?t=75152

    BTW, if you search the web, you'll find several articles in professional technician's journals that indicate that belt life in quite a few high performance engines is surprisingly short. Some of the belt service intervals were reduced by the factory to 45K to 50K miles a few years after the engines were introduced. That isn't 30K miles, but it isn't a lot higher either.

    Personally, I've decided that 5 years is as long as I'm willing to trust my belts. I put on about 3,000 miles/year, & the car is stored during salt season. If I were tracking the car, or putting on a lot more mileage, I'd change them more frequently. A couple of weekends work every 3-5 years is cheap insurance.

    ====================================
    Now here's a much easier question to take a stab at answering:

    Like any cam belt, the stress on it is maximized under conditions of maximum engine speed change. This has been said several times before.

    On the 308s, max engine speed change occurrs when such doing such as the following:

    - A fast down-shift at high speed with a bad engine RPM missmatch. This is also one of the reasons the engine revs beyond redline. Quite a few people have reported shearing off belt teeth doing this.

    - An up-shift without getting off of the throttle.

    - launching from a stop by dumping the clutch with the engine at high revs.

    In all these cases, the kinetic energy or inertia of the 308 is accelerating or decelerating the engine.

    Under these conditions, there's a lot more kinetic energy/inertia available to change the engine speed than the engine itself can generate. Changing the engine speed rapidly requires a corresponding acceleration or deceleration of the cams at a high rate, hence max stress on the cam belts.

    WOT acceleration is a lot less stressful, you have the engine trying to both accelerate the vehicle and itself. Much lower rotational acceleration.

    Even less stressful is running the engine at constant speed. However, the belts are exerting force to accelerate the valves downward, the more frequently valves are opened, the higher the stress on the belt, so higher RPMs are more demanding than lower engine speeds.
     
  15. greg328

    greg328 F1 Rookie

    Nov 17, 2003
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    Verell,
    Thanks, appreciate the in-depth response.

    So, it seems that sensible driving will reduce possible belt risk. I never abuse my cars as you described, especially my Ferrari! It seems there's a good chance that some early failures might be due to some bad driving habits.

    My concern was that WOT adventures would place my belts at an unusual risk.. I know these are performance cars, but I must admit I cringe a bit when I wring her out.

    BTW, I always try to achieve smooth shifts, up and down. In fact, I rarely perform a radical hi RPM downshift, preferring to wear brakes rather than over-rev the engine..

    Thanks again, and sorry to hi-jack this thread :)

    Greg
    77 308
     
  16. Artvonne

    Artvonne F1 Veteran

    Oct 29, 2004
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    Back in the day when lumpy old V-8's had those crummy nylon timing sprockets with the cheapo web chain, you were lucky to get 70K out of them before they jumper time. But the truth is, they almost always jumped when you shut the motor off. Run all day long, upshift, downshift, beat the dickens out of it, then shut it off and it would jump. My Ford F-350 diesel likes to occasionally throw the serpentine belt off when I shut it off. I have read several times not only here on Fchat, but way back in the mid 90's on the Flist, of 3X8 timing belts whacking out at low speed. But they go off at high speed too, and usually with more drama.

    At any rate, I doubt anyone will ever gather any real data on this issue. Most of the people it happens to dont want to admit they gambled and lost, and they also don't want anyone knowing thier car had it happen as it can be considered a bad mark. I myself would be very speculative of a car I was going to purchase, if I knew it had mashed itself. Did the combustion chambers get damaged? If so, were the heads replaced? Were they welded on? If the pistons were hit, were they replaced? When you wreck your motor are you going to tell me all of that? For every person who is honest, there are probably quite a few more who are not.

    More speculation is the fact that parts for the 308 are slowly becoming NOS. Soon there will be no new heads or engines available to neglect and destroy, only used virgin heads, and used welded up and repaired heads. I know the 308 is considered the biggest bastard out there, the "throw away" Ferrari. But myself, I really don't think even half of the original number exist anymore. If so many of us are so passionate about Ferrari, why are so many trying to take so many risks to damage them out of purely economic reasons? Why not stop and try to preserve whats left of what many call the most beautiful Ferrari ever made? They may have made a lot of them, but there is no discounting the significance of its place in autodom.

    I currently own two 1977 308 GTB's that are less than 40 cars apart. I feel very proud to count myself in such a group. On both cars Ferrari have sent me documentation stating the engine and gearbox are original to each of the cars. Today its probably not worth much to anyone else, tomorrow may be different. But I like the idea that these cars have made it this far with most of thier big parts intact. I guess if that is not important to some of you, and you want to risk damaging the motor, that is certainly your risk to take. But many of you should realise the potential damage you can cause. While a belt stripping off teeth at low speed may simply bend some valves and gently kiss some pistons, there have been engines that have totally come unglued. I personally know of one in particular that not only destroyed the block when it came apart at high speed, but also took out the gearbox.

    I look upon a car such as this as I would owning a cheap Cessna 150. If I owned a C-150 I would be FORCED to have it extensively serviced and inspected every year at a cost that could easily exceed $1000 on an airplane maybe worth $12,000. The Ferrari is faster, sounds absolutely awesome, looks lightyears better, is far more comfortable, and is worth a lot more money. Plus I can fix it all myself. Heck, it probably even gets better fuel economy. My feeling is that considering the potential damage that can happen, 3 years on those belts is quite a while. I highly doubt the FAA would allow them to run longer than a few hundred hours at most if that motor were in an aircraft. And they probably would insist on a minimum of annual replacement. How long would you trust your life to that belt?
     
  17. tvine

    tvine Formula Junior

    Jul 19, 2006
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    When it comes to preventive maintenance there is an optimum frequency. Too often can be just as bad as not often enough. Once you get to a short enough frequency that the most common failure modes have been eliminated, then infant mortality and maintenance induced failures become the driver of most failures. As one of the previous responders stated these parts are made of rubber (or something like it). Not a very homogenious material and subject to variations batch to batch. Bottom line, you take a real chance of replacing a good belt with a bad belt. You also take a real chance of replacing a good bearing and unknowingly damaging the new one during installation. There is a lot of date in the nuclear industry to back this up. Your can overmaintain a piece of equipment to failure.

    I agree that getting good data will be tough, but I thought I would try.
     
  18. jm3

    jm3 F1 Rookie

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    I dunno, I always decided they jumped when you started the motor. Seems a bit more intuitive to me.

    Ferrari content: I think they rip the teeth off when you start the motor too.

    JM
    (owned a lot of Buicks, had a lot of nylon in the oil pans)
     
  19. miked

    miked Formula Junior

    Feb 7, 2001
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    Establishing a belt change interval based on data is only slightly less probable than picking the winning lottery numbers via a computer program.

    I deal with failure predictability and life extension issues on production machinery every day. The difference is that the variables (loads, corrosion, wear patterns and cycles) are more predictable and fit within a much smaller range than the possibilities presented in the life of a 308 timing belt. You can come up with an average life cycle (years, miles) and add a cushion but there is still a large sample population with short life w/failure and longer life w/o failure.

    A Honda, Toyota, VW etc. has a more predictable life (both length and operating environment) than a 308. A Ferrari can be driven only a few miles a year for decades or tracked weekly. The problem is that a significant population of Ferraris are in each of these environments. A change of ownership can throw the car from one extreme to the other.

    Maintainence levels also have a very wide sample population. May owners will wash and wax their cars to death but the engine is filthy, leaks not corrected and routine maintainence deferred. Also a large part of the Ferrari owner population buy a car, run it hard for a couple of years, then sell it before the inevitable expensive repairs fall on their wallets. The next owner ends up with "premature" parts failure on a car that was "babied" by the previous owner.

    The life cycle data for 308 timing belts would probably not fall into a "bell" shaped curve, more like a "brick" shape with significant sample populations at the extreme ends.
     
  20. jm3

    jm3 F1 Rookie

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    I dont think any Honda, Passat or even WW1 machinery leaks oil onto the belts as much as Ferrari.

    afaik, the old seals were non-directional, but the replacements are.

    JM
     
  21. spirot

    spirot F1 World Champ

    Dec 12, 2005
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    My rear belt broke on my 308 last December... did about $6500 in damage... and I fixed it DIY style... ( with expert help from two very good friends!!!)

    Don't know the cause for sure, but think that either Wd40 got on the belts? or they were just old and cracked... all the teeth were stripped off on the bottom of the belt... bent each valve etc... a night mare is not exactly how I would put it... but it was an eye opener... the belt was between 5 - 7 years old... so was in need of replacement...

    I will say that after so much work and the car fired right up... it was pleasing... then I traded the thing in on a very low milage 328!

    my advice is that if you are past the scheduled belt change ... you are on borrowed time... could be a month or 15 years.... who knows... but if they need to be changed then change them - thats the way I sleep better at night!

    Tom
     
  22. Meister

    Meister F1 Veteran
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    I'm currently on newish belts (within 3 years) & tensioner bearings of "undeterimed age"... how lucky do I feel....

    Going to get through the next 6 weeks and then change everything... I'll let you know how I make out =)
     
  23. tvine

    tvine Formula Junior

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    Miked,

    Excellent points. With a small population and such variables in operating conditions and care it would be tough to pin down a frequency. It would be nice to hear from people who have experienced failures to hear how and when they failed. You may be right about oil contamination being the wild card.

    I re-reviewed my car's maintenance records. I had assumed that the 14 year and 48,000 mile timing belt change was the second replacement...it was the first.

    The second owner bought the car in 1983 (it is a 1979) and he was likely an engineer, the maintenance records are written in a surveyor's field book. He had maintenance done at various times but not at the prescribed 15k and 30k intervals, including retensioning the original timing belts once without replacing them. It seems that he drove the car like an adult which may be a reason that the belts did not fail. There are entries for checking valve clearances (no adjustment required), carb balancing and points replacement done at different times. Oil leaks were also addressed on a number of occassions which also could effect belt life. He did not do the work himself but it seems that he did not let things go.

    For those who think that I am treating my 308 as a disposable Ferrari, it could not be farther from the truth. I have always considered the 308 GTB to be the best styled Ferrari and the best all around road car they have built. It is well balanced and not overpowered.

    My car had numerous issues when I bought it that I have pretty well sorted out. I intentionally bought a car that needed work so that I would get to know it by working on it. I have developed a great appreciation for how they are designed and built as a result. I have absolutely no intention of selling this car, ever. My other collectable car is a 1969 Plymouth GTX convertable that I have had for over 25 years. I don't intent to sell it either.

    By the way, many parts for the Ferrari are cheaper and easier to obtain than for my Plymouth, especially 25 years ago when Chrysler was in financial trouble. The first thing to go was spare parts production. Reproduction parts were not available for many years and many are still not available. The 440 went out of production the year before my Ferrari was built.
     
  24. NYCFERRARIS

    NYCFERRARIS Formula 3

    Mar 2, 2004
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    a previous thread pettered out..but relevant here.."Shelf life of belts" could belts be sitting on a warehouse shelf for more than a few years that would degrade our life to only a few installed years of service life? Do distributors actually throw-out "expired" or aging belts? Whome should we buy our belts from...the cheapest guy out there or the busiest (faster product turn) seller. Is the dealer more likely to sell you fresh belts that the huge mark-up is worth it (ammortized over more years of service life 'cause they are fresh).

    Labor is one thing but the failure point is the bearing and/or the belt...can we control more for the belt by getting fresh belts? if so how/where?

    do fresh belts have more bounce or elasticity or resistance to indentation some type or rubber belt property that can be measured and degrades with the age of the belt that can be measured?...also if such a tool exists ..it is small enough to be used on 348 engines "belt inspection" access on the top of the rear of the engine...

    On my own cars..I keep it simple...keep up with the manuf. suggested maint. intervals...
     
  25. andrewg

    andrewg F1 Rookie
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    Retensioning the belts as I'm sure you already know is strongly advised against by Dayco the manufacuter of the belts, he could drive the car like an engineer / adult all he liked but it seems a very big risk for the sake of saving $30 on a pair of new belts!
     

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