355 engine mystery

check plugs for fouling

jd

 

Did check engine light come on? Did you pull any codes?

 

Sam:

How are you running test pipes on a Motronic 5.2 F355? Cats can be removed on the 1995 2.7 Motronics with little or no problems, but it is my understanding this can not be done on the 5.2 cars (or only with very great difficulty and potential for problems).

 

+1 .............

 

Most people with newer F355s with Motronic 5.2 ECUs replace the OEM cats with Hyperflows, which give 97% of the flow of test pipes, yet have the bungs for the multiple O2 sensors needed for the 5.2 ECU. The 5.2 is much more sophisticated and "picky" than the Motronic 2.7, with respect to required sensor input. I would really give this some serious research and thought. By not giving your ECU the proper input signals it can't properly control the engine (i.e., potential DAMAGE). I would contact an experienced Ferrari Technician and discuss this. I hope damage has not already occurred.

 

Wow! Thats amazing! Also amazing because it is a rare event that can be documented. Please will you keep us all informed in detail about what you find along with photos. This could be very educational. Thanks and good luck, i hope there is not to much that cant be put right.
I always thought that when a belt let go there would be alot of noise of bent metal. Clearly this is not the case. This event is so rare that one can only asume what would happen in the 355 if a belt snapped.

 

Usually, on cars with single timing belts, the engine just stops like someone turned the key off.
Or in this case half the motor stopped with no "obvious" noise from the failure.

 

Yes but it didnt did it, it drove home. Thats why this thread could get interesting. No one spotted that one coming on here after the symptoms were disclosed..

 

Crap!!! Hope it turns out to be an relative in-expensive fix for you...

 

This is a car with two timing belts, one for each bank. My post has been updated to reflect this. Sorry for the confusion.


The million dollar question is going to be finding out if anything else failed like a tensioner. If everything else checks out ok and the belt simply failed, very scary situation for the rest of us (not that a failed tensioner is any easier to live with...).

 

Being that its a two belt system makes it even more puzzling IMO. Because you know whats surprising, that the engine did not jam while driving. This could be due to a bent/snapped valve or guide that could jam the piston from traveling up the bore. Thus not allowing a complete cycle of the crank. So it does not matter if only one bank is running in theory the engine could still jam.
So i wonder why it did not jam the cycle, Looking forward to hearing more.

 

That could mean good news, that the damage isn't very severe.

Years ago I was driving a car with dual cams driven by one belt, internally is a chain connecting the cams together. This chain broke stopping one of the two cams from moving. Stupid me tried over and over to fire up the car, timing belt still attached turning the intake camshaft. Much to my surprise the head was not damaged and all of the valves came out alive. Both camshafts were destroyed by the chain whipping around – not an issue with the 355.

I've also taken apart cars with broken valve(s), still ran on 3 / 7 cylinders. The valve is usually pressed well into the piston or the head. That scenario usually makes a lot of noise, at least with the couple I've had the pleasure of being around when they broke or the customer comes pulling up asking what that clanking sound is.

 

Now would that not screw up alot of theory regarding the 355 cambelt snapping

 

Bad News, but I hope the damage isn't too bad. I think we'd all be interested in learning more about the belt that failed. How many years/miles since it was changed? Could the failure be from a foreign object ... that has happened to a 348 owner. Best of Luck.

 

Yes, pictures and analysis would be appreciated. Rarely do the belts actually break, usually the teeth shear off, causing the timing to go way off and of course damage to the valve train...

 

Curiosity got the best of me.

Was the major performed since last May?
http://www.ferrarichat.com/forum/showpost.php?p=137714308&postcount=55

If not, it looks like 26,000+ miles since the last major.
What year did you buy the car? Judging by past posts, it was before November 2003 (when the last major was performed).

http://www.ferrarichat.com/forum/showpost.php?p=15738&postcount=3

 

Thanks for keeping us updated mate. Yes we are interested Would you care to tell us how many miles your car has done on them belts? How does the un-broken belt look like? So many questions i have. Thanks for taking the time.

 

+355! There sure are a lot of people interested. Please keep us apprised. Thanks in advance.

 

+ 1: please post pictures of the motor with the t-belt covers removed.

p.s. sorry to hear about the problem, though