if timing belt is sereaded does it damage the engine

the dealer said timing belt was sereaded and i was looking at replacing the
engine wonder why it didnt just mean putting it back in time

--
posted from
http://www.motorsforum.com/vw/if-tim...ine-45205-.htm
using MotorsForum's Web, RSS and Social Media Interface to
rec.autos.makers.vw.watercooled and other automotive groups

"turtle" wrote in message
roups.com...
> the dealer said timing belt was sereaded and i was looking at replacing
> the engine wonder why it didnt just mean putting it back in time

I'm going to assume you mean "shredded." Is it actually shredded, as in
ripped into shreds, or is it stripped, as in some or all of the teeth are
gone?

Either way, what kind of damage might have been done to the engine depends
on what sort of engine it is.

In many engines, low compression ones, if valves are open and the engine
continues to spin the piston tops will not hit the valves.

In other engines, high compression ones, if the valves are open when the
piston comes up, the piston top will strike the valves. These are sometimes
called "interference" engines because, if mistimed, the valves will
"interfere" with the pistons. Damage to the valves, the piston tops, maybe
the main shaft bearings, maybe the cam shaft, cam followers or valve guides.
I've had timing belts strip (not shred) in three cars with high compression
interference style engines. A 1977 Fiat X 1/9, where the strike did occur.
Several valves damaged one piston punched through. The other two were 1987
16 valve DOHC VW Scirocco's. In both cases I lucked out in that the engine
was at idle at the time, stopped near instantly, and the valves were in one
of the two positions of the cam shafts where all sixteen valves are closed
at the same time. After the belts were replace one ran for another 20,000
miles before I had to retire it for non-engine related problems. The other
I'm still driving over 15,000 miles later.

Given that all you said was (I'm assuming) "shredded," and didn't specify
what car or engine, it's hard to be sure why they assume it's necessary to
replace the engine. I'm going to guess that it's an interference engine and
you were running at speed when the belt went to pieces. They may have
examined the valve stems and noted that some are stuck down even when the
cam shaft is rotated or may have sounded the engine or other approaches to
assessing the damage.

- Bill

"Bill Leary" wrote in message
...

"turtle" wrote in message
roups.com...
> the dealer said timing belt was sereaded and i was looking at replacing
> the engine wonder why it didnt just mean putting it back in time

I'm going to assume you mean "shredded." Is it actually shredded, as in
ripped into shreds, or is it stripped, as in some or all of the teeth are
gone?

Either way, what kind of damage might have been done to the engine depends
on what sort of engine it is.

In many engines, low compression ones, if valves are open and the engine
continues to spin the piston tops will not hit the valves.

In other engines, high compression ones, if the valves are open when the
piston comes up, the piston top will strike the valves. These are sometimes
called "interference" engines because, if mistimed, the valves will
"interfere" with the pistons. Damage to the valves, the piston tops, maybe
the main shaft bearings, maybe the cam shaft, cam followers or valve guides.
I've had timing belts strip (not shred) in three cars with high compression
interference style engines. A 1977 Fiat X 1/9, where the strike did occur.
Several valves damaged one piston punched through. The other two were 1987
16 valve DOHC VW Scirocco's. In both cases I lucked out in that the engine
was at idle at the time, stopped near instantly, and the valves were in one
of the two positions of the cam shafts where all sixteen valves are closed
at the same time. After the belts were replace one ran for another 20,000
miles before I had to retire it for non-engine related problems. The other
I'm still driving over 15,000 miles later.

Given that all you said was (I'm assuming) "shredded," and didn't specify
what car or engine, it's hard to be sure why they assume it's necessary to
replace the engine. I'm going to guess that it's an interference engine and
you were running at speed when the belt went to pieces. They may have
examined the valve stems and noted that some are stuck down even when the
cam shaft is rotated or may have sounded the engine or other approaches to
assessing the damage.

- Bill


Most times a broken t-belt only requires a head rebuild. On occasion the
pistons are severely damaged, but only they need replaced, not an engine.
Good luck.

"LG" wrote in message ...
> "Bill Leary" wrote in message
> ...
>> "turtle" wrote in message
>> roups.com...
>>> the dealer said timing belt was sereaded and i was looking at replacing
>>> the engine wonder why it didnt just mean putting it back in time
>>
>> I'm going to assume you mean "shredded." Is it actually shredded, as in
>> ((..omitted..))
>> A 1977 Fiat X 1/9, where the strike did occur.
>> Several valves damaged one piston punched through.
>> ((..omitted..))
>
> Most times a broken t-belt only requires a head rebuild. On occasion the
> pistons are severely damaged, but only they need replaced, not an engine.
> Good luck.

Yes. In the case of the X 1/9 I noted, it was a head rebuild and the one
piston replaced.

I've also seen instances on non-interference engines were all that was
needed was to replace the belt and retime the engine.

- Bill

On 3/18/2013 3:56 PM, LG wrote:
> Most times a broken t-belt only requires a head rebuild. On occasion the
> pistons are severely damaged, but only they need replaced, not an
> engine. Good luck.

One must consider the possibility that there is piston damage but the
rest of the engine may also have problems too, hence the recommendation
to replace it. The OP didn't really give any information such as engine
or mileage or even engine condition prior to the failure but I suspect
that if the timing belt failed as described that the engine was lacking
maintenance and wasn't in good shape anyway.

--
I'm never going to grow up.

Good point.

"PeterD" wrote in message ...

On 3/18/2013 3:56 PM, LG wrote:
> Most times a broken t-belt only requires a head rebuild. On occasion the
> pistons are severely damaged, but only they need replaced, not an
> engine. Good luck.

One must consider the possibility that there is piston damage but the
rest of the engine may also have problems too, hence the recommendation
to replace it. The OP didn't really give any information such as engine
or mileage or even engine condition prior to the failure but I suspect
that if the timing belt failed as described that the engine was lacking
maintenance and wasn't in good shape anyway.

--
I'm never going to grow up.