I feel silly - No power to Glow Plugs BJ42 3B

[dmbgo]

Hi everyone, please excuse my unfamiliarity with the BJ series, I just bought a BJ42 with a 3b engine last week.
Everything was fine when I got it, but it was a bit difficult to start the next morning.

Aha says I that'll be them there glow plugs!

I tested the glow plugs with a meter and sure enough one was open circuit. I went to the local parts store and bought 4 new glow plugs, installed them and replaced the bus bar.

The motor hasn't run since.

I put the volt meter between the glow plug terminals and ground and found that there was no power to the glow plugs, even though the glow plug light came on for abot 5 seconds when the key was turned on.

Looking further I found that there is power to the metal bar that goes across the manifold and under the glow plug bus bar between the third and fourth glow plugs, however I can't for the life of me see how the glow plugs get their power. The bus bar is coated with a black insulating material so that it doesn't connect to the live bar under it.

After all that, my question is how is the glow plug bus bar meant to get its power?

I am sure that this must be really simple! Is there a disconnected power wire laying inside the engine bay laughing at me? I cant see any spare wires that might provide power to the glow plug bus bar, but there could be one somewhere.

I feel very stupid and I am sure that if I could see another 3b motor I would see the problem straight away.

Sorry to take up your time with such a small issue, but I've searched everywhere and cant find anything that shows the actual wiring. There are plenty of circuit diagrams etc, but I dont know what the physical connection is meant to be.
Thanks in advance
Dave

[lostmarbles]

A photo or two would have been good to enable us to see exactly what you're talking about Dave.

My BJ40 has a power lead connected to the glowplug busbar (at No. 4 glowplug I think) and then the busbar supplies the power from there to the other plugs.

Wherever there is an electrical connection it must of course be "bare metal" to "bare metal".

It puzzles me that you appear to have an insulating coating preventing current-flow at one or more connection points when your busbar isn't new (and has been fitted/working before).

But anyway - You must ensure you have clean metal at each connection and a good contact area at each connection.

[dmbgo]

Thanks Tom,
The insulating coating on the busbar is only between the glow plugs, there is bare metal where it connects to the glow plugs with a good electrical connection. I just started the engine by jumpering the bus bar for 5 seconds from the plate that goes under it, which does have power. So at least I know that it is definitely a glow plug issue.

I am sure this has been caused by me - oh how I wish I had paid more attention to the setup before removing the glow plugs.
I definitely dont have any power wires to the bus bar or the glow plugs themselves.
I Have looked again for a wire that might5 have fallen down between the engine and firewall but I cant find one.
I will go out and take a photo.
Cheers
Dave

[beejay42]

Hi Dave,
I just went out and took a photo of mine,
you can see the black cable attached at the end- it comes out of the wiring harness just down to the right.

Mine is a manual glow system though- it sounds like yours is automatic? Might have a different looking cable?
Let me know if you want any other shots or angles.

[RufusTheDufus]

dmbgo - What year is your BJ42?

[beejay42]

what Rufus said,
also, fill out your profile...

and...


welcome to MUD

here's a couple more photos of mine if they are relevant.

[RufusTheDufus]

BTW, the wire will be heavier gauge, most likely stranded with an eyelet connector on the end of it. I'm guessing 10 gauge or 8 gauge wire. It would be bigger than most of the other wires in the engine compartment. The eyelet is sized to fit over the post on one of the glow plugs. The wire should originate from the firewall near the glove box.

[Joe Egolf]

Yep , My 1981 BJ42 is wired same as pics above , you must have the hot wire attached to #4 glow plug and have good metal to metal connections.What i want know is where you live and what glowplugs you got at local parts store.Do you have 12 or 24 volt system?? What voltage glow plugs did you take out and what voltage did you put in??

[RufusTheDufus]

I've seen some with the hot wire connected to #3. It doesn't matter if it's on 3 or 4. The current will follow the path of least resistance anyway.

I think the voltage on the plugs must be OK since he was able to hot wire them for 5 seconds and the engine fired up.

I've always wondered what the correct plug voltage is for a 12 volt system. I think mine are 10.5v but they take forever to warm up.

[dmbgo]

Thanks for the quick replies and great photos.
Right. I've edited my profile
I've got a 1984 BJ42 with power steering and disk brakes and rust.

Mine is different from your photos (thanks again) and I now have some photos of my own setup.

Here is the left hand side of the engine, I think it might be a super glow setup?

[IMG][/IMG]

Here is the area around glow plug 4. I was wondering if the bar under the glow plug bus bar is the current sensing rail that I have read about in some posts, perhaps this is meant to connect to the bus bar? Shorting from this to the bus bar made the plugs glow and started the motor.



Here is the bus bar, you can see the black insulative paint between the glow plug connections

[beejay42]

No probs Dave,
I'd go hunting for loose thick cables in the region and check them with multimeter while someone is turning the key in the cab to the glow cycle. There cannot be many options.

My cable is significantly thicker than anything else in the region (aside from battery leads and starter motor etc).

(EDIT- looks like yours is quite a different system... I dunno.)


Also,
And just an observation of your engine-
your accelerator cable looks a little loose.
Mine was the same- and I just tightened it up (see the first photo I posted). Taking out the slack nearly completely fixed my BJ bunny hopping.

[Joe Egolf]

My old plugs were 8.5 ,so i replaced them with PT104-8.5volt plugs There is a lengthy post /discussion between me and lost marbles and amauer in this diesel section regarding glow plugs and voltage etc etc..I am still curious where Dave lives and how he found glowplugs so quickly for a 3B if he is in the states?

[RufusTheDufus]

That's the superglow system. My FSM doesn't cover it so I can only make guesses on how it works.

I have labeled what looks like the current source wires and the relay that controls the flow of current. I've labeled two wires with question marks that appear to be part of the circuit. (Just a guess.) The "X" looks like the point of contact between the Superglow system and the glow plug bus bar.




You should check for voltage on the bar that runs perpendicular to the glow plug bar (the one under the "X") while the glow plug circuit is active.

[RufusTheDufus]

There's an excellent description of the super glow system in the second post of
this thread

[dmbgo]

You're right about the accelerator cable being loose, the whole thing is a work in progress. I spent the weekend rebuilding the front axle (oh the grease) It was haemhoraging oil from the front hubs, new front brakes, new clutch slave cylinder, just noticed a big crack in the exhaust header (thought it was loud), it has 1/8th of a turn of play in the steering and I haven't even started on the rust.

Anyway, I'd just like to get it going again I hate the idea of making things worse.

Someone asked what type of glow plugs I used. They are Bosch GPT-214, replacing ND 067100-1450, which I think is ok.

[dmbgo]

I was thinking exacly that Rufus, there is 12.5 volts on the bar that runs under the bus bar which the thicker cables connect to when the key is turned on. however the underside of the bus bar has the same black insulation on it as the top, so I cant see the cross over point being the intended source of power for the glow plugs, also I think it would be likely to corrode over time.
I have now had a really good look and I cant see any unconnected cables / wires

[RufusTheDufus]

Is there continuity between either of the mounting posts on the crossover bar and the bar? It appears to be isolated with rubber mounts but it's hard to tell. If either of the mounting posts are electrically connected to the super glow bus bar I suspect that there should be a jumper cable/wire between that post and one of the glow plugs.

[dmbgo]

Just going out to check - should have looked at that BRB

[dmbgo]

Both of the mounting posts are connected to ground and are electrically isolated from the current carrying crossover bar,so that's not it, however I cant see why the crossover bar would extend under the glow plug bus bar other than to provide power?

[RufusTheDufus]

It makes sense that it would be a current source. But corrosion could be a big problem. Do the two bars actually make contact or are the just very close to each other?

[dmbgo]

The two bars touch, but there is undisturbed insulation on both sides of the bus bar, the insulation looks original and I am sure that the way it is now it couldn't be the power connection for the glow plugs.
I was wondering if someone might have changed things from standard and also wondering if the glow plugs were working when I picked it up?
The vehicle started easily then, but I think the engine had been warmed up. I didnt check for glow plug voltage before I replaced the glow plugs, just assumed they were all working apart from the faulty one.
(wry grin)

[lostmarbles]

Thanks for the photos Dave. They explain a lot about what you were talking about.

You certainly have a different (more complicated) glow system to mine and I'm picking (same as others here) that it is what we call a "superglow system".

This is very interesting because I haven't noticed any BJ42 fitted with superglow before (and I had begun to think they all had simple manual systems like my old BJ40).

And it has been hard enough for me to come to grips with everything associated with my manual system (actually - I'm not sure that I have yet) so I'm not really qualified to offer much help on yours - Other than to say that there MUST be a power connection to your glowplug busbar somewhere. And I'm sure they wouldn't be making this contact by simply allowing it to rest on that other busbar (that sits perpendicular to it).

Perhaps your 2 bars were soldered together at that point and accidentally broke apart when you were working around there??????

[lostmarbles]

Originally Posted by dmbgo

The two bars touch, but there is undisturbed insulation on both sides of the bus bar, the insulation looks original and I am sure that the way it is now it couldn't be the power connection for the glow plugs.....

Following on from my last post - Perhaps you have accidentally flipped the busbar over and it is bare (uninsulated) where it sits above the other busbar when it is flipped back????

[RufusTheDufus]

I went out to the garage to look at my spare 3B. I think it had the superglow system on it at one point. I found this part that looks like it would have been used to tie the superglow to the glow plugs. (the quarter is for size reference) This might be what you are missing.

[RufusTheDufus]

BTW, this part fits perfectly between the superglow bar's mounting point and the #4 glow plug.

[lostmarbles]

Originally Posted by RufusTheDufus

BTW, this part fits perfectly between the superglow bar's mounting point and the #4 glow plug.

I bet Dave's rummaging around on all fours with a torch looking for it right now Rufus

[RufusTheDufus]

It fits on the engine like this

[beejay42]

Great work Rufus!

at least it doesn't look too hard to reproduce one if Dave has lost his.... erhmm.. I mean if Dave's BJ never came with one

[dmbgo]

Wow, thanks so much! Its all starting to make sense. Although I am often a bit careless and often can't see what is in front of my nose, I am sure in this instance that I didn't lose that part, the only nuts I undid are the 4 glow plug nuts to remove the bus bar and the glow plugs. I am not even going to bother getting my knees dirty or to unnecessarily flatten my torch batteries!

I am now convinced that the part was lost before I got the car. I am now going to fabricate the part and test it.

There may still be some fault with the superglow system that led to the part being removed in the past, so I will check the duration that the glow plug voltage is applied for when I fit it.
Thanks again, I will report back soon.

[beejay42]

now I look at this photo again (from here)- it looks like something like this peice is just visable?



EDIT- and one interesting snippet I found while googling (all right, I am procrastinating today) was this
"Alternator brushes needed replacing, caused the "superglow" glow plug system to cease to function cause it is grounded through the alternator brushes. $3 part, WOW easy to replace, one screw, one hex nut, a little solder and Presto, done!"
from here http://www.carsurvey.org/review_78585.html

anyway, good luck.