[Vwdiesel] cold start issues

Erik Lane eriklane at gmail.com
Wed May 21 09:24:35 PDT 2008

I've heard of them having decent looking resistance and still not
being good. But I've never seen it myself. If they have good
resistance then they've always worked for me. If I remember right then
they usually were something around 1 or 2 ohms or so for one glow
plug? If you can check the amps that they are each drawing that is a
MUCH better way to see if they are working, and you can watch the
numbers as they warm up - they pull less and less amps as they warm
up. Shows you pretty quickly exactly what is going on in there. If you
don't have a meter you can do the hillbilly trick of just using a
jumper wire (meaning a little wire, not one for jump starting a car.)
and hook one end to the positive of the battery as you brush the
contact of the glow plug - each one disconnected from the rest and
doing one at a time while they're installed in the car. If you get a
healthy spark it's a pretty good sign. Although I've also heard that
glow plugs can fail to a shorted condition, but I've only ever seen
them fail to an open state.


On Wed, May 21, 2008 at 8:08 AM, Patrick Dolan <pmdolan at sasktel.net> wrote:
> Yes, they can fail and it has nothing to do with power getting to them.  You have to remove the harness and test them for resistance.  You can do an overall (1/4 of spec resist for all 4 in parallel), but best off to do each one.  If they have failed, you will get infinite resistance (open circuit).  Of course, if you are doing this in parallel, that means that if you shoot all 4, 1/3 spec resistance means one is dead, 1/2 = 2 and full resistance = 3 dead.
> ----- Original Message -----
> From: Kneale Brownson <knealeski at sbcglobal.net>
> Date: Wednesday, May 21, 2008 8:36 am
> Subject: [Vwdiesel] cold start issues
>> The 94 Jetta TD doesn't want to start when cold.  I have power to
>> the glow plugs, I get fuel, the battery shows 12.4 volts static.
>> If ambient temperature gets somewhere above about 60 degrees (F),
>> it'll start readily.  Just plain won't catch when colder if it's
>> sat for more than six or eight hours.
>>  Could the glow plugs not function despite power to their wiring?
>> How would I test those?
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