Has anyone actually had a timing belt snap on an F355?

There has been a couple on here in the 3x8 Forum. One was surely FOD (Highway Token).

355? Don't know.



I do bet there have been a few more than reported though.

But how many is anyone's guess.

 

The belt changes are preemptive measures. In other words, insurance to save from disaster.

 

However, here's a recent discussion which includes a link to a belt failure on a 355.

http://www.ferrarichat.com/forum/348-355-sponsored-bradan/515015-looked-97-spyder-flabbergasted.html

Looked at a 97 Spyder, Flabbergasted! Post #32

 

Here's another

http://www.ferrarichat.com/forum/348-355-sponsored-bradan/506904-snapped-timing-belt-355-a.html

 

The entire reason the factory changed the timing belt interval from 5 to 3 years was because of timing belt failures on 355s. They did not do it to make their product more attractive in the eyes of consumers.


A visual inspection of an old belt is a worthless endeavor. Typically a failed belt look perfect except for the area where all the teeth are missing and 3 seconds prior to failure it would have looked perfect by your standards.

 

Always amazing what inferior materials Ferrari sometimes seems to use. Take something contemporary, the Porsche 928 S4 and later. 4 camshafts driven with one single belt. Porsche gave it 8 years or 80,000 km. And it seems that this was no problem at any time .....

Cheers, Bernhard

 

Mine at about 5 years. Many times the belt is OK but the tensioner bearing seizes and then it's not OK. 7 bent valves and about 17K to sort out.

 

The belts are not made of inferior materials. 8,750 rpm is much harder on a belt/belts than 6,300.

 

I personally know two 308's that snapped belts. One about 3 miles from the shop. The other was well into the service life but still not due to be replaced.

(I snapped one on a Ford Ranger back in 06. 1990 model so it was 16 years old.)

 

One happened to a friend that operates a Ferrari repair shop on his own 308. He didn't believe in 5 year changes and still doesn't. He makes all manner of excuses why it broke.

 

I broke one on a 1992 BMW 520 in 2012. About 292,000 Kms. OEM belt. Never changed.

It saw LOTS of 80-130mph action over the years. Good Autobahn miles.

No harm done except a tow to the next BMW repair shop.


But these cars are NOTHING like a Ferrari.

 

I am just wondering about the words being used. I see "snapped" and "broke". Have you gentlemen seen the belts actually rip or part so that the belt is no longer a closed loop? I have seen many failed belts, but they have always just stripped the teeth or lugs away.

I did a 308 QV belt change and found several holes punched through the belt. Surely a small stone got thrown up got between the pulley and belt. I am doing a change right now on a Mondial 8. The lower part of the belt guard was broken away. I suspect that it was done to get the water pump out without removing the A/C and guard. That belt also must have had something thrown up into it. It was ripped about 1/3 of the way across. Both these cars were still operating normally. I have never seen a belt actually break open.

 

Still? Wow. No "lesson learned" there I guess...

 

I'd get into that a little more but it has been said so many hundreds of times already there is no more to be said. At some point someone should just look at the thousands of posts on the subject. Adding to that number just makes it harder and less clear.

 

Visit the 928 forum on Rennlist, or just look through google images. WAY more 928s snapping belts than was ever a problem with Ferraris.

Nice thing about the 928? It has a nifty timing belt tension warning light to drive the owner insane at random intervals.

Yeah - I'm a 2 time 928 owner, and I'd own another one in a heartbeat.

 

I had a belt fail that snapped on my 85 QV. The cause was believed to be due to one of two possibilities. Mice had gotten into the cover and left some nut shells in there which might have causes the belt to ride on the pulley fence and cut the belt which then snapped. That was the initial diagnosis. The other possibility, found once the repair was initiated, was that one of the drive bearings was starting to go and this could have resulted in misalignment causing the belt to ride up on the fence being cut, and then it snapped. In either case, it was pretty apparent that the belt ran up on the fence and was cut as all the teeth were gone around the entire circumference approximately 1/4" in from the edge. Damage was minimal, 2 intake and 2 exhaust valves which were barely bent. Repairs, including a full major service and all fluids/filters changed was under $10k. Belt age was not considered to be a factor.

 

I had a balance shaft belt break on a 944S2 motor a few years back. It failed with a break that opened the belt's closed loop. Fortunately, the belt dropped nearly directly onto the engine undertray, missing getting caught up in anything else.

That was Day 1 of my ownership. It looked like they had never changed the belt, which was 20 years old at the time!

 

I have repaired may F355 engines with broken timing belts. Almost always the belt is stripped at the drive sprocket and it occurred at startup. Also most of the time it was a car that was not driven for a while. At closer inspection I found that the belts had stripped at the point where the belt tensioner had been pushing against the back of the belt. I wonder if the pressure against the back of the belt pushing the teeth apart for extended periods could possibly crack the belt???? Anyway I would recommend frequently running any car with a timing belt. The belts don't wear out, they dry out.

 

As long as you don't have to go downstairs to the basement ..... Upstairs is cheap.

 

Hi Johnk, zygomatic, and Fixerguy

Thanks very much for your informative replies. Now I know that some belts do "break" in the literal sense of the word. The forces must be high as the belt material is tough with very high tensile strength. I took the belt from the Mondial that was partially ripped and tried to tear it the rest of the way. I could not do it with my hands.

Thanks.

 

I wonder how many belt failures are related to tensioner failures. I have seen my share of belt tensioner bearings that were either seized, stiffening or (on the other extreme) coming apart. All with the stock bearings. Never with the Hill version.

 

Most of them..... by far.

Either by tensioner / idler pulley issues or by drive gear issues, as the primary failure mode.

 

When I bought my car, I had the choice of 'with' or 'without' a fresh belt service. I chose 'without', not to save money, but to be sure that all the relevant 'while we're in there' fixes were done - and done by someone I trust.