Glow plug light taking longer than expected to turn off

Hi:

I have a 1992 Jetta TD. The glow plugs are abour 3.5 years/45K kms old. The
car
has 415K kms on the odometer.

I'm in Toronto (Ontario, Canada) where the temps are around 25-30 C
nowadays.

For the past few days, I've noticed that the glow plug light on the dash
is taking longer than expected to turn off before I turn on the ignition.

Usually, it takes around 10 secs. for the light to turn off on a cold engine
but today I timed it and it took over 20 secs. for it to turn off.

Another thing I've noticed that after driving for about 10 mins. when I
stop, turn
off the ignition, wait for a few secs. and then turn the ignition half-way,
the light still takes over 10 secs. to turn off. Normally, after driving for
a
while, it will barely turn on, maybe for a split second as the temp.
is adequate to fire the engine. The engine temp. needle on the dash is
normal,
i.e. around the middle of the meter after driving for 10-15 mins.

The engine does fire normally in both cases - cold and after driving
for a few mins.

Any thoughts? Weakened glow plug(s)? Time to replace them?

Thanks in advance.

AJ.

AJ wrote:
> Hi:
>
> I have a 1992 Jetta TD. The glow plugs are abour 3.5 years/45K kms old. The
> car
> has 415K kms on the odometer.
>
> I'm in Toronto (Ontario, Canada) where the temps are around 25-30 C
> nowadays.
>
> For the past few days, I've noticed that the glow plug light on the dash
> is taking longer than expected to turn off before I turn on the ignition.
>
> Usually, it takes around 10 secs. for the light to turn off on a cold engine
> but today I timed it and it took over 20 secs. for it to turn off.
>
> Another thing I've noticed that after driving for about 10 mins. when I
> stop, turn
> off the ignition, wait for a few secs. and then turn the ignition half-way,
> the light still takes over 10 secs. to turn off. Normally, after driving for
> a
> while, it will barely turn on, maybe for a split second as the temp.
> is adequate to fire the engine. The engine temp. needle on the dash is
> normal,
> i.e. around the middle of the meter after driving for 10-15 mins.
>
> The engine does fire normally in both cases - cold and after driving
> for a few mins.
>
> Any thoughts? Weakened glow plug(s)? Time to replace them?

Maybe the temperature sensor is dead? the glow time is based on coolant
temperature. The long glow times do indicate a problem in that direction.

Remco