Glow plug dilema

[leftcoastjeff]

I seem to be having considerable trouble starting early in the morning as opposed to some trouble caused by my return lines leaking air over time.

The GP controller WTS light stays on for 1-2 seconds then switches to after glow, that's never happened to me before.

No start, unless I crank for 60 Sec. (bad idea) I plug in the block heater for an hour, then it starts better.

So I am debating the push button or replacing the controller.

Am I missing something?

LCjeff

Ps. this truck has so many issues, hopefully they won't be too much $$/time to fix.

 

[gandalf]

The WTS light stays on only 1-2 seconds? It sounds more like you have 1 or more bad glow plugs rather than a controller problem. You know the drill: start testing your glow plugs.

 

[leftcoastjeff]

I just did a search for glow plug replacement and got next to nothing.
Which brand of GP's should I get/avoid?
Should I worry about removing the old ones if they test good?
And which way is easier and/or better to test.
The guys at Napa had 2 of one brand and 1 of another.
They can get Autolite ($9.95), Champion, Bosch, AC and Delfy ($22.50 Ea.)(maybe)

LCjeff

 

[The Warden]

You really want to get Motorcraft/Beru plugs...pretty much any other brand risks an early burning out and the tip swelling, which can lead to serious problems On that note, if you get a glow plug loose but it doesn't want to come out, be VERY careful...you'll want to bring that piston to TDC before trying to manhandle the plug out. That way, if the tip breaks off, it won't go too far and you might be able to fish it out through the injector hole. If you don't get the tip out and try to run the engine, you're risking catastrophic failure

As far as testing them, I prefer an ohm-meter...unplug the wire from the plug, put one lead on the terminal on the top of the plug, and the other one to ground somewhere...ideally to the body of the plug. You should get 2 to 5 ohms; if you get 0, it's shorted and you're getting current going through the plug without heating up the tip, and if you get open resistance, the plug is dead. Here's a graphic of the testing points:

You must be registered for see images attach

If you don't know the history of your plugs, I would suggest replacing them all...certainly beats tearing into it just to do it again in a few months if the others are old and potentially close to failure. I would make sure that all connections are clean (harness to plugs, connections on the controller, etc) while you're at it, and you should be good to go

Hope this helps some...best of luck with it!!

 

[franklin2]

Don't just replace them. Check them first. You should get a very low ohm reading when using a ohmmeter, or you can use a testlight, put the alligator on the + side of the battery, and then touch each tip of each injector after you take ALL the connectors off. If the testlight lights up, that glowplug is good.

I will tell you besides the glowplugs causing this problem, the connections in the wiring will cause this problem also. I replaced the bad glowplugs on my truck, but after a few weeks it started the short glow like you are experiencing. I thought I had burnt one out, took the wires off and test the plugs, they were all good. Put it back together and while I was scratching my head about what to do I tried it and it worked. I filed that experience away and sure enough a few weeks later i was having trouble again. This next time I went out and didn't check anything, I just twisted the connectors back and forth on each glowplug and sure enough the problem went away again.

There is also a wiring plug over near the A/C box that supplies power to the glowplug system, and it likes to melt(this is on the newer style controllers). Mine was melted, so I cut and spliced the two large wires to eliminate that problem.

I did finally go with the manual button, and I have no more problems. The intermittent connections "fake out" the brain in the controller, but it all works fine with my thumb pressing down on the button for a few seconds. I am sure if you repaired/went over the harness you could probably get it working properly, but I didn't want to mess with it.

 

[jim x 3]

Don't just replace them. Check them first. ...
I will tell you besides the glowplugs causing this problem, the connections in the wiring will cause this problem also. ...

X2.

My WTS time recently went to zero, afterglow only, simultaneous with difficulty in starting.

I checked and replaced 2 bad GPs. (I use the cheaper BOSCH and never have had a problem with swelling or removal BTW).

Still zero WTS time, afterglow only. So I figured the GPC was bad. Relay on top worked fine if manually triggered (by removing white wire and grounding relay terminal and then providing +12VDC to the other relay input terminal). So I suspected the control logic potted below. Time for a new unit. But wait - bad connections from GPC shunt output to the bullet connectors will mimic a bad GP.

I gently removed then squeezed each bullet connector (in calibrated Vicegrips). Now they slide on the GPs with a bit of resistance. System now works properly with suitable WTS on times.

So my troubleshooting sequence is:

1. Check GPs individually and replace as necessary - should be near zero ohms.

2. Check for good ground at GPC black terminal.

3. Check for +12VDC at relay secondary terminal and, with Key ON, at relay red wire input terminal.

4. Check that all bullet connectors are tight on GPs - by feel.

5. Check resistance in brown WIRING from GPC output to each bullet connector individually - should be near zero ohms.

6. Check GP relay above controller - via manual trigger, should be no voltage drop across relay secondary terminals.

7. OK, after those tests, it may be time for a new GP controller (the logic) or a manual replacement.

I suspect that, after checking and replacing GPs, some GPCs get replaced (or circumvented with a manual system, because a manual system will work even without perfect connections) when the real problem is in the GPC output connection(s) to the GPs.

Regards,

Jim

P.S. Please amend/correct the above troubleshooting procedure if I've left something out, or to clarify. Thanks.

 

[metalminded]

you'll want to bring that piston to TDC before trying to manhandle the plug out.

whats the procedure to do this?

 

[leftcoastjeff]

I tried the ohm meter, but I couldn't get a solid reading so I used the test light.
All the plugs light the lamp.
I'm thinking of putting in a push button.
I believe there are 2 different controllers for different years, somebody mentioned a purple wire, I could NOT find it.
I'll go search now, if you can direct me to the right instructions I would be very thankful.
I could not get her going this morning ever with the block heater on for an hour.
LCjeff

I just looked at the article in the tech section by Tbiglug, but that controller looks nothing like mine, HELP!

 

[leftcoastjeff]

So after looking at my controller I see no purple wire!

I have 2 large yellow wires on one of the large terminals on the top opposite the wavy piece of metal.

I have 2 red wires on one of the small terminals,

one white wire on a small terminal with a paper tag that says "white wire only on this terminal"

one small yellow wire on the big terminal with the wavy metal connector and

a small green wire on the terminal that the other end of the wavy metal connector below the relay on the controller (I think that is the controller)

Also there are 2 large black? wires on the controller

With the key on I get 12vdc on both of the small terminals.

Where should I wire the pushbutton?

LCjeff

 

[CurtIDI94turbo]

Hi Jeff, Are you sure you tested your glow plugs properly? It sounds like exactly the same problem I had all the way to plugging in the block heater for easier starts.

Per Franklin ---> “you can use a testlight, put the alligator on the + side of the battery, and then touch each tip of each injector {Think he meant Glow plug} after you take ALL the connectors off. If the testlight lights up, that glowplug is good.”

Take a look at the picture that the Warden put up. Where it shows positive lead is the only place you want to touch. Hope this helps.

 

[leftcoastjeff]

Hi Curt,

Yes, I have tested the glow plugs with a test light and they were all working as such.

Thank you,

LCJeff

 

[The Warden]

Yes, I have tested the glow plugs with a test light and they were all working as such.

Did you test them with an ohm meter? Also, how did the plugs that came off the glow plugs look like? It's possible that, even with a good plug, the connector's corroded enough to not make a good connection, which would make the controller think the plug's failed. Also, it is possible for a plug to short "open" so that there's still continuity with ground (i.e. the test light will light up) but it won't actually heat up. If you test the plug with an ohm meter and you get zero resistance, that plug's bad. IIRC you want 2 to 5 ohms of resistance.

Re: the purple wire, that's for the '84-'86 6.9l (the '83 trucks used a completely different system). The '87+ 6.9l/7.3l that use the solid state controller have a different way to bypass the controller...take a look here: http://www.oilburners.net/articles/glowplugbypass.htm (note that I have not tried this myself, so I can't confirm 100% that this is good, but it looks correct to me).

 

[leftcoastjeff]

Thanks, I'll retest the plugs with the ohm meter.
I just could not get a consistant reading.
So, I should not see either an open or a dead short? otherwise they are OK?

I'll reread the article tonight and try again tomorrow,

LCjeff

 

[The Warden]

So, I should not see either an open or a dead short? otherwise they are OK?

Basically correct. IIRC there's a resistance point beyond which the controller assumes the plug's dead, but I don't know that number...hopefully someone else knows and can post it. IIRC below 2 ohms is bad, and the "ideal" range is between 2 and 5, but I imagine anything below 15 to 20 should be okay...