Glow plugs ?? circuit testing - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• Glow plugs ?? circuit testing by monst on 22 Nov, 2021 21:33
• 
  
  Car was running and parked it.
  I don't know maybe a week or two ago was when it was last driving.
  There was not an indication of  a starting problem previously...
     I have been having an issue with a water leak. I have to address.
  I believe it drips in and causes electrical problems.
  Like  the wipers and the heater fan stops working. It is intermittent.
    So anyway, this car cranks over. Yesterday it would do a slight pop
  crank.............. pop.......................crank....................... pop..
  an ever so sligthly pop. You get the idea.
  The fuel gauge looked pretty low (the depths of E)so I figured It would be better
  to throw some fuel in it... After doing so... I cranked for a while till black was
  coming out the exhaust.... Glow plug light behaves lights bright... kick back
  on the key and try  and start.....   no pop at all today...
           I need to figure out if I am getting power to the glow plugs.
  What is the best way to test them?
  
  Also, what about corrosion? 
  
  Needs some insight into this, Thanks, Monst
  
  
  
  
  
  
  
  
• #1 by ORCoaster on 22 Nov, 2021 23:20
• You can put a test light on the wire going to any of the glow plugs and turn the ignition switch.  If the light on the dash is on then you should have voltage on the test light or better a meter.
  
  
  
  Was the fuse blown?  Just bad connections along the line from the battery to GPs.  If you have water leaking in then pull the relay off its plug up under the dash and re-plug it.  Maybe the corrosion went deeper into the relay.  Most come apart easily and you can see inside it for corrosion. 
  
  Hard to armchair an electrical problem of this nature but we can try.
• #2 by monst on 23 Nov, 2021 17:07
• Thanks for the reply.
     Will  check that out and see if there is power out the the  GP's.
  
  I mean like  Cuz... 
        (the light on the dash  does it's normal dance. "like they are heated up and say's "crank it over")
  
      What is the likelihood that all the Glow plugs  would suddenly stop working??(like lightbulbs burning out all at once, on the string of Christmas lights)
  It is cold here now, where before..... not soo cold.... so....
  Will see if I have power....
  
  thanks again, MOnst
  
  
• #3 by ORCoaster on 23 Nov, 2021 22:56
• The chances of them all failing at once is low.  More likely you have one or two still trying to make it warm enough to start.  Multimeters that have a resistance setting on them are great for finding the ones that are bad.  If you don't have a meter then cycle them a few times and feel them.  Are they warm?  Then likely working.
  
  
• #4 by fatmobile on 24 Nov, 2021 00:22
• If one were to go you might not notice.
   Then another goes and it gets worse.
   You might still have one good glow plug.
   If they are autolite they could burn out at any time.
   
   To test the plugs use a voltmeter to see how much voltage they are getting.
   12 volts means something is wrong, not drawing enough amps to draw the volts down.
   Should be near 11volts or less.
   
   Use an ammeter, 60 amps or so, clamp one end to the battery and the other to the glow plug buss.
   From there it depends on what kind of glows you have,.. they pull from 9 to 12 amps each after glowing for 7 seconds.
• #5 by monst on 24 Nov, 2021 22:40
• Thanks for the insight.
  
  I spent sometime on it this eve.  rather chilly out.
  but, I have gotten somewhere.
     First thing well, not quite the first thing but,
  pertaining to the GP's.  I looked to see if I had
  12V(or should say power at the buss) cuz  I was
  using a test lite.  The light didn't light. Mild corrosion.
  Scraped it... still nothing.  So tracing it back to the
  relay block bridge(guessing that is what it is called
  on the firewall) I noticed the metal fuseable on it was
  shot. So I tried to get the light to light before it on
  the philips screw.  It did not light there either.
     I then dropped the panel covering the fusebox.
  I reached  in there to situate the box a little and
  found several fuses loose... they were falling out
  of their sockets....... When I pushed them back in
  I had power on the one terminal on the Relay Block Bridge.
         I removed the Relay Block Bridge   and found some
  thin aluminum flashing laying around in the shop and made that little fuseable and
  installed it on the Bridge.....
      After installing the Bridge back in and  testing the buss
  I had power on it now.
       She still is not running but, she pops initially at crank.
  This brings be back to what I first noticed the other day.
  THough, I felt back then that the GP's were not working
  when cranking for quite some time.... when I returned
  to the engine compartment....  I was seeing little lovely
  air bubbles returning back to the fuel filter.
  So  I am thinking the fuel line check valve is not working
  (stuck open) and fuel is siphoning back to the tank....
  I am thinking the IP is dry as a result of this.
      Tmorrow I am going to run it out of my Diesel fuel
  container....  tie in a hose at fuel filter inlet....
  see if I can get it to run.
  
     Let you know where this goes tomorrow.
  
  So how "hot to touch" will these glow plugs get if they are working ?
  Be nice to just do a quick check with a finger. If I stick a finger in there
  do I have to worry about  Burnin' me fingie?
     
                              Thanks Happy Turkey, MOnst
  
  
  
  
  
  
• #6 by ORCoaster on 24 Nov, 2021 23:15
• Touch quickly and then again more slowly.  With the amount of metal that will soak up the heat, I don't think you will smoke your poker but do so at your own risk. 
• #7 by fatmobile on 25 Nov, 2021 02:30
•  I added a light in the cluster that shows when the glows are getting power.
  Doesn't show if they are all working but shows the relay and fuse are good,.. or not.
• #8 by ORCoaster on 26 Nov, 2021 00:04
• I watch the voltmeter gauge.  It shows a lower voltage when the GPs are on and will jump up a bit when they cycle out. 
  
• #9 by monst on 26 Nov, 2021 17:17
• Both are good approaches to stay proactive to whether or not GP's are actively working.
  
  Like in my case they were not working. And suspecting they had not been working for quite some time (all the warm months anyway).
  
  So going on the notion of a possible fuel issue, I ran or should I say tried to run out of my diesel/kero container which had three gallons of
  recently purchased diesel.  This provided no relief from the problem.   Ok??
  
  This is when I decided to consider the stop solenoid.  It has been rather moist/wet/damp for months and months here.
  I pulled the connector off the terminal and cleaned the terminal on the stop solenoid. It was corroded. I did not clean
  the connector. Would be nice to scratch something in there as well.
  
  The vehicle kicked right up, (quicker than ever, now that the glow plugs work too)!
  
  From what I was reading about the stop solenoid, It can be heard clearly when it is powered,
  I have not checked this.  Is the Click when the stop solenoid is powered quite audible?
  
  AND
  
  Since we are on the topic of corrosion, I could start another thread or just mention it here.
  
  From what I understand the Jettas (92:mkII)  can have issues where they leak.
  
  I noticed that the back seat floor is wet.  I don't know but, it sorta narrows down the leak to
  the driverside of the vehicle.  I need to pull the driver's seat I think.  Maybe just rip out the
  interior (being both seats and carpet and read bottom seat).
  
  But, like anyone knows or think what I might suspect for potential leak locations?
  
              Thanks, Monst
  
• #10 by fatmobile on 27 Nov, 2021 01:46
• It might be a tail light leak.
   Sometimes they run forward,.. at least they did on the rabbits.
  Otherwise I'd check along the bottom of the door card.
  
   If you have the key on and touch the stop solenoid with the wire you can hear the solenoid click.
• #11 by scrounger on 27 Nov, 2021 14:07
• Have you tried feeling the glow plugs after a cycle? They each should be warm/hot.  The glow plugs many times don't just fail but get weak.
  
  If you are going to have the injectors out you will be able to see which glows get hot. 
  
  Glow plugs can break off upon removal. Be sure that you put anti-seize on the threads of the new ones.
  
  If you are getting corrosion issues, that should be addressed.
  
  If one glow is weak or not working the others will have the same amount of time on them so might be best to change them all.
• #12 by sgnimj96 on 16 Dec, 2021 08:14
• If glow prug issue is suspect,   I just take them out and jump them on the battery to see what they do.
  Gotta have the 8&12mm ratcheting wrenches for that job unless you only do #3 and #4.
  
  Jumping them straight off the battery leaves no doubt.    I've seen several fairly news ones that failed to glow well,
   and one that took lots of power but didn't glow at all.
  
  
• #13 by Dakotakid on 16 Dec, 2021 21:21
• WHAT? No, please do not encourage straightforward-logical methods for solving problems like this. What are you....some kind of trouble-maker?
  
  This will totally RUIN the whole Rube Goldberg effect and aura. We just can't have this sort of thought process around here!
• #14 by ORCoaster on 16 Dec, 2021 22:49
• We really work at trying to downplay the Rube Goldberg effect here.  Sorry, it keeps the confusion of the newbies down.  They are still sniffing the air wondering what that smell is coming out the tailpipe, their gasser didn't smell like that!
  
  So heck yeah, straight and logical at least for a bit on the simple stuff.  We can Rube the conversion stuff.