testing glow plugs

[Stoop]

Easiest way I have found to test the glow plugs, is turn on the interior light, and click on the key..  if the interior light "dims", your glowplugs (or some of them at least) are working.

I had the fuse go the other day, and knew right away, cause the int light wasn't dimming.

After that, yeah, pull off the bus bar, and check them in the car (ohmmeter) .  If they are bad, you gotta pull the bus bar to replace them anyway.

[Rabbit TD]

All that stuff about ohms and such is making my head hurt. I "want" that stuff, but you "need" a battery charger and a compression tester. Always know your  compression values and the battery charger will test the glowplugs. They will get red hot if they are good, toss them if they don't.
With an inexpensive product warantee, Pull-a-part gives me an endless supply of glowplugs. It sounds like you need at least 2 if not 3. Goodluck-warren :mrgreen:

Diesel blocks from the vw's never make it to the wreckings yards around here... engines always get pulled first.   :x

Ill just order a few and change atleast the easy 3.. lol.. $20 a piece  :shock:

 
They should make a short one for cyl. #1 :cry:

[Smokey Eddy]

I wish IDI GPs were as easy to take out as the TDI's.

I just tested my TDI's GPs and they were all fine. But this morning it had a rough time starting...  

for the first time EVER my 1990 IDI starts twice as fast as my (parent's) 2000 TDI. Why could this be?
To not jack this thread anyone with know-how please pm me? the coldest it gets at night was -2C, -5C is the low for tonight.

(I HATE HOW EXPENSIVE GP'S ARE! :evil: )

[Jettagli16v]

Hmm.... My car would not start this morning (First day below 50F in a month), which brings me back to this thread...
Since I have not been there before,
Can all 4 glow plugs be removed with the IP in place,
or must you remove the IP to get the #1 GP?

Ill try the infrared pyrometer trick and see if I can shed some light on this.

Also will be tring to pull off Vince's patented pimping of said wiring at the same time....
looking like a bit of work for me this evening..

Thanks,
BRAD

[clbanman]

You can remove the #1 glow plug without moving the I.P. or the injector lines. I did it by loosening the nut and then using a small magnet on the end of a screwdriver to turn the nut and eventually pull it off.  Same for the glow plug itself.  Reverse to install.  Slow but doesn't affect your timing.

[Jettagli16v]

*Edit: I did not read the above post.... sorry!*

Ahh, so only #1 is accessible without removing the pump and lines?
That sucks.

I am hoping for a problem common to all 4,
It used to take 2-3 cycles to get it started in the cold
(according to most here, that may indicate a bad plug or 2)
and this morning, I got nothing!
(started the car for like 5 or 10 minutes, in 30-45 second intervals)

Does the light still come on without GP's functioning,
or is it a smart light?

Thanks,
BRAD

[Vincent Waldon]

Ahh, so only #1 is accessible without removing the pump and lines?
That sucks.

Actually I think he means the opposite, as in "*even* #1 is accessible without removing the pump and lines".

Having said that, for the minute or two it takes to remove the hard lines I always pull them... there's only so much busting up my fat knuckles can take.

[clbanman]

Yes to Vince's reply.  I was trying to address your worst case scenario.   While it might not be the most efficient way to do it, when I was doing this I just didn't want to touch anything that might cause other issues (read: that I could break).

Oh, and it's not a smart light.

[jtanguay]

a tool like this one might help in those tight spots  :wink:

[Jettagli16v]

**I really hope I am not bugging you guys yet.... Thanks GTD!!!!

OK,
So here's what I know after a cursory glance just after work:
Glow plugs (at least #3 and 4) have power (via test light on the buss bar),
They cycle for about 15-25 seconds (50F air temp)
and then shut off.
They turn on when I turn the ignition to start,
and stay on for the duration I am cranking (thought the dash GP indicator does not come on then)
The GPs have power for about 3-5 seconds after the light goes out, and I can audibly hear the relay clicking closed.


Also, I checked the stop solenoid, and it has power with the ignition on position.

It is just a test light, so I dont know if I have 12.7v or 10.7...

I can smell fuel coming from the exhaust, approximately as much as before... you know, when the car started!

Am I thinking straight to be focusing my efforts on the Glow Plugs?
It just seems like the obvious thing, since it was cold this morning (30F)
and this is the only time the car has not started.
Previously on our 10 other nights below 40F, I usually had to start it 3-4 times before it would run.

THanks so much!
-Brad

[Jettagli16v]

well, damn!
I just got the best worst news ever...
Glow Plugs are fine...
Removed all 4 (injector lines intact)
With an 8 & 12mm gear wrench, two long screwdrivers and a bit of magnet trickery.

All 4 gave me between 1.3-1.7 ohms and looked very good:
Black tips, with a bit of buildup that scrapes off with a dental pick.

However, before we took them out,
we were seeing a 20-40F rise in surface temperature in the head (right above glow plug) on cylinder #4 that diminished to a 3-5F rise by the time you got to cylinder #1 on each cycle of the plugs.
That is what made us sure that at least one (on the #1 side) glow was not working.
There was a bit of corrosion on the buss bar and nuts particularly on cylinders 1 and 2.
Could it be just resistance? The mating surfaces of buss bar and glow plug look pretty clean... the corrosion looked much worse on initial inspection, before we realized the buss bar is copper...
Now is a good time to pimp my GP wiring....

Advice appreciated!
-Brad

[vanbcguy]

Do you still have the injectors out?  Really no better way to see if the plugs are working than to power them up while you can physically SEE them.  They'll glow bright cherry red in a few seconds if they're any good.

[Jettagli16v]

The injectors are not out, but all of the glow plugs are
and they all glow when hit with 12v.
Now I am buying new Bosch Duraterm's, and putting together the parts to pimp my wiring ala Vince! Hope to get that done tomorrow after work.
My sincere hope is that it was a glow plug / wiring issue. I keep going  back to the temperature difference across the head during glow plug cycling.

Still looking for the issue, though!
thanks
-Brad

[turborabbit]

If you have four glowing GP's, save your money on the Duratherms. If you know the timing is even close, check your compressiion, you might need that money for rings. Just my 1 cents worth-warren

[Jettagli16v]

Too late, and not my style...
While I appreciate your sentiment,
I cant spend three hours removing a $10 part (of unknown age) to re-install it (cause I know it will fail within days as a matter of principle). I am also going to do Vince's wiring upgrade, while I am there.
(I am big on the "while we are here")
I have already bought the new Duraterms, relay and fused distribution block,
and if I need rings, I will get them.

I will have the new plugs installed and the wiring upgrade done tonight (hopefully) and we will see what I have got then.
I suppose the next logical step may be a compression test,
(which requires new heat shields, after removing the injectors, i think...)
though given how well it ran and started, I am hoping it is not a catastrophic mechanical failure.

I had really wanted to do other stuff before I took the motor apart,
but perhaps the Gods have other ideas for me!

More to follow!
-Brad