Technical Threw serpentine belt now car won't start

Currently reading:
Technical Threw serpentine belt now car won't start

GateTech3963

New member
Joined
Jul 27, 2025
Messages
6
Points
27
Location
Ohio
2013 Fiat 500 Pop - So I downshifted too hard/too many gears while trying to avoid a collision and threw the serpentine belt. I was able to put the belt back on, but now the engine just cranks but will not fire to start. No strange noises from engine or any other indication of damage. Is it possible the timing belt jumped timing?
 
Model
500 Pop
Year
2013
Mileage
78000
2013 Fiat 500 Pop - So I downshifted too hard/too many gears while trying to avoid a collision and threw the serpentine belt. I was able to put the belt back on, but now the engine just cranks but will not fire to start. No strange noises from engine or any other indication of damage. Is it possible the timing belt jumped timing?
Doesn't sound too good.:(
First thing I would do is a compression test to see if engine mechanicaly sound or not.
 
:eek:


If you just "put the belt back on" then absolutely it's jumped timing !!!
But a "serpentine belt"? that's going to be the Aux (fan) belt eh? Doesn't men the overspeeding didn't make the timing belt jump a tooth or two though? However I'd be taking a look at the crankshaft position sensor as it may have been damaged if the serpentine/aux/fan belt caught it when it jumped the pulleys?
 
But a "serpentine belt"? that's going to be the Aux (fan) belt eh? Doesn't men the overspeeding didn't make the timing belt jump a tooth or two though? However I'd be taking a look at the crankshaft position sensor as it may have been damaged if the serpentine/aux/fan belt caught it when it jumped the pulleys?

My bad , I assumed he was talking timing belt , which could also be described as a serpentine belt, just with ribs/cogs on it. 😛

I think Bugsy Mike thought the same maybe..... :unsure:

Did it have fine longitudinal ribs on it or coarser transverse ribs
 
But a "serpentine belt"? that's going to be the Aux (fan) belt eh? Doesn't men the overspeeding didn't make the timing belt jump a tooth or two though? However I'd be taking a look at the crankshaft position sensor as it may have been damaged if the serpentine/aux/fan belt caught it when it jumped the pulleys?
Thanks for this. It was the "auxiliary" belt. I'll check the crankshaft person sensor. I literally just replaced it a few weeks ago.
 
Thanks for this. It was the "auxiliary" belt. I'll check the crankshaft person sensor. I literally just replaced it a few weeks ago.
Please do let us know the outcome won't you?
My bad , I assumed he was talking timing belt , which could also be described as a serpentine belt, just with ribs/cogs on it. 😛

I think Bugsy Mike thought the same maybe..... :unsure:

Did it have fine longitudinal ribs on it or coarser transverse ribs
Hey ZaphodB, calling it a Serpentine belt only triggered my thinking because I got used to the chap I made friends with who was my daughter's neighbour when they lived in Southern Maryland - he would refer to a "serpentine belt" when he was referring to the fan (aux) belt.
 
I've always seen and heard the auxillary belt referred to as a serpentine belt, for the AC, alternator and power steering. It has the longitudinal grooves.

I'll let you all know what I find, once I get it home. Unfortunately it's still sitting along the interstate.

Thankfully, a friend has a bore scope and compression tester that I can borrow.
 
I've always seen and heard the auxillary belt referred to as a serpentine belt, for the AC, alternator and power steering. It has the longitudinal grooves.

I'll let you all know what I find, once I get it home. Unfortunately it's still sitting along the interstate.

Thankfully, a friend has a bore scope and compression tester that I can borrow.
Fingers crossed for you (does that mean "good luck" over your side of the pond?).
 
My bad , I assumed he was talking timing belt , which could also be described as a serpentine belt, just with ribs/cogs on it. 😛

I think Bugsy Mike thought the same maybe..... :unsure:

Did it have fine longitudinal ribs on it or coarser transverse ribs
No in fairness after reading it all I knew serpentine was the auxilary belt, my concern was the banging it down through the gears bit.
i always remember a novelty award at on of the Kart racing events I used to compete in around 1969, it was a complete racing conrod bent in half and mounted on a display plinth, it said flat out in third then back into second!!! Should have changed up.:)
I think Serpentine as on moderns cars they "snake " about all over the place.;)
 
No in fairness after reading it all I knew serpentine was the auxilary belt, my concern was the banging it down through the gears bit.
i always remember a novelty award at on of the Kart racing events I used to compete in around 1969, it was a complete racing conrod bent in half and mounted on a display plinth, it said flat out in third then back into second!!! Should have changed up.:)
I think Serpentine as on moderns cars they "snake " about all over the place.

No in fairness after reading it all I knew serpentine was the auxilary belt, my concern was the banging it down through the gears bit.
i always remember a novelty award at on of the Kart racing events I used to compete in around 1969, it was a complete racing conrod bent in half and mounted on a display plinth, it said flat out in third then back into second!!! Should have changed up.:)
I think Serpentine as on moderns cars they "snake " about all over the place.;)
Unfortunately I was cut off in a construction zone on the interstate. In my hurry to avoid a collision, I braked and downshifted at the same time to slow down and apparently dropped it from 5th gear to 2nd. I'm sure this didn't do the engine any good.
 
It all happened so quickly I just didn't think that far ahead. I was just trying to avoid being crushed.
We all do illogical things under stress. I sympathise with you. Having driven Manual shift cars for most of my life, in the sort of situation you faced there, I'd have smashed the clutch pedal to the floor and stood on the brakes hard whilst, with both hands on the steering wheel, looking for possible escape routes if it all went Pete Tong. ABS in these circumstances would have saved me from going hopelessly out of control with all 4 wheels locked? Shifting down the gearbox or even grabbing the gear lever wouldn't have been in my head.

Got my fingers crossed this turns out well for you.
 
I don't know what engine is in the car

I don't know what caused the belt to come off

I do know over revs through down shifting will not cause the belt to come off, unless there is an underlying problem

The over revs has just caused it to find the weakness in the system

Several possibilities

Clutch dampener in the alternator seized

Vulcanised crankshaft pulley, failed

Assuming it's has one, a faulty tensioner, either bearing or nylon washer worn away causing it to tip over and throw a belt

Damaged belt

My guess is it's come from high revs to low, the clutch in the alternator has jammed, the mass inside the alternator has carried on spinning and caused the tensioner to flick up

Here a tensioner jumping around at idle, due to a faulty alternator pulley, first part is slowed down




This is a guess, and you need to get the engine running first
 
Last edited:
Back
Top