This is a great thread. While I take excellent care of my 330, my father tends to pretty seriously neglect his 1981 308 GTSi. He drives perhaps 1,000 miles a year, and the car has never been repainted. (And it looks like it!) Believe it or not, his 1981 308 still has the original cam belts. That's right: they're around 25 years old. I don't really think that I would be able to persuade him that they should be changed. His car may therefore be the one used for "destructive testing." I'll certainly let you guys know if they fail. So far, they don't even squeal. --Matt
Funny thing about retentioning a timing belt.. I'm also a certified Ducati motorcylce tech..in the service manual and part of the 600mile service is to re tention the timing belts. These engine spin to 12000rpm all the time..and you can retention those belts..the pullies are tiny and the the tentions are mechanical. But when we do the tentioning we must use a speacial tool that will mesure the belt vibration in htz. If it too tight or too loose we know right away. I have started to use this tool on the Ferrari's as well..work awsome. Although everytime I remove a belt from an F-car I do replace it..but I'm just wondering why you can retention a belt on a 12000rpm engine but not on an 8000rpm enigne..oh..belt change time on a Ducati is 2 years regarless of milage..
Your tension tool is working while the engine is running, correct? What does this tool look like? Does a loose belt have a lower or higher vibration as measured in Hz? How does that value compare to a properly tensioned vibration?
If we compiled real world data for intervals of time and mileage between changes for both belts that failed and belts replaced prior to failure we could control chart the data to determine a real time/mileage window that we could expect the belts to last. There are several variables that would have to be controlled, but there are enough people on this board with 3X8s that we may well be able to develop statistical limits for how long we could expect belts to last in each model. Could produce some interesting data. Troy
Even Ferrari at one time said to ck and correct belt tension at 1500 or so miles but almost every Co incl Ferrari has gone away from that philosophy. Ferrari has been using an ultrasonic measuring device for belt tension for a number of years for all the belts and it works quite well. You can find the tension specs in the shop manual. If you do not use the specs for the ancillary belts you will either have a slipping belt or you will have water pump and tensioner bearing failures. Sound familiar? If your Ferrari guy is not using one of those to tension belts maybe, well never mind.
Untrue, loose Ferrari belts don't squeal: The only time you'll hear squealing from a timing belt is when the tensioner bearing is seized, or nearly so. The squeal is because the belt is slipping on the bearing. The belt will still have full tension, or very close to it until it's worn thru by the slipping & runaway failure occurrs, at that point it's indeed too late. The P* tension sensor works just like I was figuring it did. Nice integral design with the tensioner mechanism. The P* tensioner is a dynamic tensioner, ie: the belt tension is continuously provided by the tensioner's spring. Unfortunately, the P* design doesn't transfer to the 3x8. You're making the erroneous assumption that the 3x8 tensioner pulley can move, thus actuating the switch. The 3x8's static tensioner only moves during the initial manual tension adjustment, then the tensioner pulley is rigidly locked down by the thru-bolt. Thus, some other tension sensing mechanism must be used for the 3x8. Hence my comments about the need for design & cost. I'm less familiar with the 348's tensioner design. It looks like it could be dynamic, if so, it may be more amenable to a P* style sensor. The belts don't stretch. The only way a belt can be loose at 6K-8K miles is if, during belt installation, it either was either improperly tensioned, or the tensioner pulley bolt wasn't properly torqued down. This is equivalent to leaving the drain plug out during an oil change.
If I drive from the heat of the desert in Dubai up to the top of a frozen glacier in Norway, then back again, I'll have ZERO stretching in a Ferrari belt?! Amazing. These must be belts made from very high quality materials. So you agree that the cheap $15 Porsche timing belt sensor design would work on dynamic Ferrari tensioners...good...it's good to find common points of agreement in order to be constructive going forward.
I should have typed in that I was kidding. After all, if we could tell that our belts were too loose by simply listening for a squeal, we wouldn't need a tension sensor...
Correct on every count but I will add that I have seen more valves bent on cars that have dynamic tensioners than those with fixed tensioners. The belts did not fail per se, the tensioner did. Simpler is better. One of the reasons you don't hear of belt failures on other makes, but the outcome is the same. Same thing with chain drive motors. Chains almost never fail but tensioners do. Even the Ferrari motors that have dynamic belt tensioner devices (355/360), the tensioners have had a rather high failure rate but due to the fail safe design no harm is done. It only causes a rattle in the front of the motor when cold. Many of you are probably driving around with failed hydrostatic tensioners and don't know it. I am often critical of some of Ferrari's engineering but that piece was very well thought out.
Gents: Just brand new to ferrari, my dream has finally come true, found and purchased a 1988 328 with 9,600 original kilometers. The vehicle was with a wealthy collector who has now purchased a Bentley, absolutely impeccable shape shell, cosmetics and drive train. I take delivery tomorrow and will platform tow to my home. I am a historic British car restorer and have now met my dream. I will begin doing a major service on this vehicle as it has been sitting. I have been able to acquire a resonable workshop manual off the internet however detail around changing the cam belts is sparse. Help with information would be greatly appreciated, in particular I believe there are markings on the head inside the cam covers to assist with stablizing the cam into TDC, also a technique for securing cam for releasing the tension of the idler. Obviously marking of the gears with white out is a must, but from what I have read working from the top of the head is the preferred method. Also, any suggestions around removal of o-rings, gaskets would be appreciated. My plan is all fluid flush and change, belts, joint inspection, brake inspection, new tires. The engine runs great, good oil pressure, although sitting it was run periodically. Thanks Go Ferrari
Phil, The pic is right after i put the timing cas cover on or took it off (?) after i had a timing bearing failure. I am pretty sure the main pulleygear was real tight, I even remember trying to remove it. I think it has a woodruf key holding it on also. I did not turn the engine without the pulley though. What would happen if you did ? would the gear slide forward? Rob
Gary - A true 30K service on a 328 includes far more than simply putting a new belt on and changing fluids. Please consider new bearings, gaskets, filters and hoses. Check the suspension and brake bits carefully. If the car has been sitting still (even if the engine was run occasionally) you could have all sorts of brittle bits in there.
Yes, but you don't even need to turn the motor for the gear to move. Even tensioning a loose belt can generate enough thrust to cause the gear to slide. Being a helical gear it's position on the crank snout changes cam timing dramatically.
I understand the fibers in the belt are kevlar or a close cousin. These fibers have negligable stretch up to their yield point. So the stretch from your trip would be so small as to not affect belt tension. I don't know enough about the details of the 355/360 dynamic tensioners to know if they could be modified to take a P* style sensor, but yes, conceptually they work like the P* tensioner, so might be modifiable.
Just had a major service performed on my '86, at about 32K miles. I bought the car in '89 with about 14K on it, so unless the previous owner did it, this was the first time the cam belts were changed. Maybe I was just lucky.
New belts absolutely have tooth-side Kevlar webbing, with an almost waxy feel. They're not cheap. But frankly, I can't fathom why anyone would cheap out on timing belts, tensioner bearings, or bulkhead water hoses. If you're going to be cheap, maybe use an Anco wiper insert or Turtle Wax. http://ricambiamerica.com/product_info.php?products_id=261164
That's cool... Almost twenty years. What condition were they in? I'll still lay claim to knowing the car with the oldest original timing belts.
Well, I bought a 78 308GTS with 15k miles, and the original belts! First thing I did was have a major service performed, along with new coolant and fuel hoses. It was a beautiful "garage queen", and was lovely to drive...but man, 21 years old with the original belts? It was a hand grenade waiting to go off...fortunately not on my watch.
Loose belts have been reported by several of the professional mechanics who post here. I've also discussed them with some local professional mechanics. A few months ago I helped Birdman change the belts on his Mondial QV after 20K miles. Belt was incredibly loose, but then we also found the cams on one bank timed 180 degrees out!!Yes, the engine will run that way, quite well it turns out! We also found a couple of other things that all together indicated that the previous service was badly botched. It's very easy to end up with a loose belt if you don't understand how to setup the tensioners properly during the service procedure.
So what do you have to do to determine if the belts are too loose. Can it be seen or felt without taking the covers off?
Unfortunately, you find out when you pull the covers off. Best way to avoid loose belts is to make sure you've torqued the tensioner bolts to spec, then as a final check, run the engine after a belt change before reinstalling the covers & watch the belts to make sure they're running smoothly. The long section shouldn't vibrate more than about 1/8" if they're properly tensioned.
My old fart opinion, just like my friend Verell. Belts are like tires. if you don't use them they will flat spot or in the instant of belts they will harden in the postion they are left in. The more you use it the longer they will last. I drive my car at least once every two weeks. I'm waiting 5 years and at least 20 to 30K miles. Of course where the car in kept comes into the thought process too. I dont keep it out doors in the rain and the sun. So, it is not a garage queen, but regularly driven above 130 MPH Kelly
