To change or not to change(Timing belt ? solved)

Like many members of this board I felt that changing the timing belt every 2-3 years (depending on who you talk to) was a waste of money and overkill. I felt that 5 years was soon enough to do the belt if the car was driven on a regular basis. I was wrong. My car , 91 348tb with 57000 miles , last had the belts changed back in Aug. 2001 at Ferrari of Dallas with 41000 miles on the odometer. I was not planning on doing the belts until Aug of 2006. Anyway in mid November 05 the car was having some running issues and was sputtering and misfiring. I had it towed to the shop for diagnosis. Turned out to me minor a sparkplug worked it's way loose. I told the shop that since it was already there and had a oil leak to go ahead and do a major service on it since I didn't need the car around the holidays. The timing belt was indeed showing some cracks in the rubber, maybe it would have lasted till Aug. maybe not. I know that from now on I will change the belt every three years. Here are some pics of the belt..
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Nice save.

Because you had an oil leak was there an sign that oil got on the belt? Also how many miles a year did you put on the car?

 

I think there is some logic for being more conservative on timing belt replacement with a 348 since it's a single belt system that drives the water pump too -- JMO.

 

Another point is could the belt have been sitting on a shelf for many years prior to installation?
Perhaps we should request Dayco put date stamps on them!!

 

No the oil hadn't gotton to the belt. Between Aug 01 and Nov 05 it had about 16600 miles put on it. So around 4K per year

 

I will qualify in saying I follow the dealer recomendation for major service on my 308 and 348.

As with all the controversy with changing belts, I still don't understand why they don't last longer.

My Acura is 100,000 miles for belt change. I had a Porsche (similar driving use as my Ferrari) and dealer recomended changing at 60,000 miles. Even the Ferrari owners manual recomends 348 belt change at 52,500 miles.

Does Ferrari use inferior belts than other manufactures?

I can understand preventive maintenance, but as the cost of major service goes up and the price of some of the older models goes down, you would think that someone could engineer a belt that would last a little longer if not as long as some other auto makes.

 

Well I think that sort of explains it right there. You don't drive the car very much. Your numbers come to a little over 330 miles driven a month. Your belt just showed that not driving the cars will cause the belt to age faster. This is very good information. I would be curious to see the condition of a belt that has the same amount of time on it but with higher milage. My guess would be that it would be in better condition.

Very informative post.

So for those of you that don't put alot of miles on your car, the gargage queens, take a look at his pictures and change your belts every 3 years or 30k miles.

 

Everyone can speculate all they want as to how long a belt will last until it goes "snap". If these were aircraft (and at the cost of even the low end Ferrari's you could own a pretty nice Cessna 172) the FAA would be stipulating when they would be replaced, and we all wouldnt be arguing about it. I am thinking these 3X8, 348, 355 were aircraft engines, they would have belt replacement times of annually, or 300 hours, whichever came first for civilian use. 300 hours at an average of 50 mph would equal 15K miles. I would also think these belts would need 50, or 100 hour belt inspections between annuals, and again, if these engines were in aircraft, commercial use would probably dictate 100 hour replacement times. I just don't think they are reliable enough beyond that period to risk someones life. There are many reasons they arent lasting like they do on newer cars, but its all moot, they arent, so lets deal with it.

When you calculate the damage a broken belt can cause, somehow we have to figure a realistic point of replacement, or find a way to either lower the cost, or extend the interval with better materials. I really think, all things considered, these belts need date codes, so we know thier age before they are installed. Unless I can determine the age of my new belts I bought for my 308, before I install them they will end up in the garbage. Additionally, if Ferrari cant provide a better belt, then we should find someone who can, made out of the highest grade material we can get. Kevlar or something. We need to find the best idler pulley, or a different design, that is more bullet proof. I also think we need to find an accurate way of determining the correct belt tension instead of relying on a silly spring pushing on a steel tube in a cylinder. This belt failure crap is probably my number one fear of owning this car. I would rather replace it once a year than risk damaging the castings and possibly blowing $10K to fix it. Some dont like points, I dont like welded up heads. I dont even want to know what a blown belt of a 348/355 would cost.

 

IMHO,
That isn't a 'silly' way of doing it. It's a very controlled way to do it. Any mechanical engineer engineer will tell you that the force exhibited by a spring under a fixed amount compression is very precise & repeatable as long as the spring isn't stretched beyond it's elastic limits.

As long as the 308 belt stretcher springs are kept clean, & rust free, they'll continue to provide repeatable tension settings belt change after belt change.

 

Great that you caught that, but IMO, that belt had something trapped under it (bolt, nut, stone), causing the tear. I seen it many times before.
A three week old belt could suffer the same fate.

 

They are not tears they are splits. All pieces of the belt are thereyou can only see them when bending the belt as I did in the pics

 

Yes, in a perfect world you would be correct, and I would probably agree. But what is the length and tension of that spring, and what kind of lubricant on the slide? There is no data in the manual, even on the QV. I would argue, that someone like Dayton would have a specification for tension, that some kind of tensiometer could test it and perhaps we could get uniformity.

I also looked in the newer manual, and it says "check belt every 9,300 miles, to 12,500 miles, and replace at 25K miles. I would say that is a minimum spec. And I also resubmit, we need dating on these belts. Think of it, its possible to buy a belt that could possibly be 20 years old off a shelf, and we couldnt tell the difference. That isnt really what I would call new. Spartas belt really shouldnt look like that in that short of time. Unless the belt was made back in '89 maybe? Sparta, is it a Dayton, or a Ferrari belt? I understand Dayton has a date code.

 

Okay I think you are getting a little confused here. The spring is only use to set the stactic tention on the belt. In other words, the spring only pushes on the belt to get the proper tention then the locking bolt holds it in place. So the springs job is done until then next time it needs to put tention on the new belt. The spring isn't constantly moving the way a dynamic tentioner would. So you only need the lubrication to keep the spring from rusting, and for ease of movment inside the containment cylinder.

I think this is more of a way for them to get you into the dealer more often than it is to prevent something from breaking.

I think your on to something here. Or maybe someone claimed the work was done, when it never really was. People have been know to lie.

 

No, I wasnt confused, I know how it works, or how its supposed to work. But what I am saying, is how do we have any clue how much tension it is putting against the belt? Without a spec on the spring, we have no idea of its required force. Also, somewhere way back, someone made a post about some tensiometer spec on these belts that the factory used. But the numbers were meaningless without thier tool. I worked around airplanes just enough that I know there would be a tension spec and a tool you could use to read it. It may not be an airplane, but the motor costs as much as one.

 

Yes there is a tension spec, and yes there is a tool to read it. Is the tool really needed? I'm my opinion no. Why? Because a fellow 348 owner bought one. He let the spring do the work, and tightend down the lock bolt after all the slack was out of the belt. Then he checked the tention. Guess what, it was right on. So why spend the coin on a tool you don't really need? But if you really must know, then go ahead and buy one. I'm saving my money.

However it would be useful to check the tention on the belt after say, a year of operation. But even then your gonna have to pull the whole dang engine just to check the the tension on a belt? Not worth the trouble if you ask me. Plus you can only adjust the tension once in the first 930 miles after the new belt has been put it. Again not worth the trouble of removing the entire engine. So to me it really doesn't justify the cost of the tool.

 

You have to love the idea that your Bubweiser has born on dating, but a belt that requires a $5,000 service does not.

 

Has anyone modified their 3x8 (by cutting an access panel to the engine like in the 360) so that changing the belt won't necessitate engine removal or is this not possible due to the placement of the engine (belt area not facing the backs of the seats).

 

Belt changing on a 3X8 does not necessitate engine removal. I've done belts twice myself.

And I agree with Verell. He is correct. And I'd like to add that the amount of friction in the device pales by comparison to the spring tension. The force that is consumed by friction is negligible.

I listen to the bearings and reuse the tensioners.

 

I love this post. It says so much.

 

Or maybe someone claimed the work was done, when it never really was. People have been know to lie.[/QUOTE]
I bought my 81 308GTSi Jan 2005. The last documented was the 30K in 1989.
The shop that did the work verbably confirmed the maitenance included timing belts replacement. The seller who is also a mechanic insisted that he had never seen a belt fail by age, never the less I requested that the belts
be serviced b4 I took posession ( I had a 90 mile drive to get it home).
The seller told me I was right, the belt behind the A.C. had NEVER been changed. It had NOT FAILED in 39950 miles and 24 years! Both belts were
chaged and bearings. I only drive 1500 miles a year and am going to service
the belts every 4 years.

stephen

 

When I bought my 328 the first thing I did was have the belts replaced. I saved the old belts so if I ever sell it I can show the invoices for the service as well as the belts.

 

excellent thread, very interesting, thank you all.

i have changed the belts twice now on the 308.
twelve months ago, i stripped the disgustingly filthy belt tensioners, for the first time .... i cannot now remember what level/amount of hmp grease i applied to the spring area inside the tubes.
if (by any chance) i applied slightly too much, am i in any danger of having the lubricant melt and subsequently contaminate the belts ?
many thanks in anticipation.
cheers, d
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you silly old fool to much grease will spray on the belts

 

I'm not familiar with 'hmp' grease, or know it by another name. However, if you used either wheel bearing grease, or even white lithium grease, & it didn't squeeze out while installing the belt, IMHO, you don't have to worry about grease from the belt stretcher springs melting out & causing problem.

1) The melting point of the grease is much greater than the temperatures in this area which are no higher than the coolant & oil temperatures.

2) Even if it melted, I"m pretty sure the grease would flow down the belt stretcher, along the mounting stud & onto the block.

BTW, here's belt stretcher tip for the older 3x8s:
If your belt stretcher doesn't already have it, drill a small (~1/8"/3mm) drain hole in the bottom of the spring mounting hole. I usually find some water & significant rusting of the spring & inside of stretchers that don't have that hole.

 

thanks verell ... hmp - high melting point.
thanks again,
cheers, d