Ford glow plug connection?

Hi all,

Just got round to checking the voltage to the glow plugs on daughters

07 Connect (they were mentioned in the fault codes) and noticed a connector that looks like it has melted to some degree.

Basically there seems to be a small 'fitting' that is mounted off the front of the engine on the n/s that has the thick red wire coming out of the bottom and going to the glow plugs. This fitting also has a threaded stud sticking out of it and the feed from the loom connects onto that (like on an alternator or old ignition coil). The threaded terminal can be lifted out of the fitting and looks like there has been a high resistance connection that has got hot and melted the plastic where the threaded terminal should be held vertical and solid?

Initially I saw little or no voltage on the glow plug bus but after pulling and re-plugging said terminal I then saw ~14V on there (with the engine running).

Googling about it seems it's not unknown but I've not seen a solid reason for it yet? eg. Is it just something that happens when it gets old or maybe due to a low resistance glow plug or poor design? I ask as there is no point replacing the mini loom if it's only going to melt again?

Cheers, T i m

Reply to
T i m
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I have known lugs to become high resistance. The wire might be good, but the crimp terminal could be less so.

Reply to
Fredxx

I think the insulation has melted a bit on the end of the feed cable where it's ring-terminal (lug?) bolts onto the stud that is part of the glow plug loom, but I think that might be as a consequence of the whole connector thing getting hot, rather than the ring terminal to the cable etc.

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Maybe I could cut all the bits off, crimp a ring directly to the glow plug bus, bolt them directly together and insulate the joint with some sleeving? Or replace the connectors with a suitably rated Powerpole connector?

Cheers, T i m

Reply to
T i m

I have seen this before.

In essence the contact of the copper cable and crimped lug has oxidised and deteriorated, causing some resistance and/or poor contact between the cable and lug. Resulting in local heat the and melting of plastic.

In my case I removed the lug from the cable by opening out the lug. Not easy! I then cleaned the cable best I could and soldered the lug back on using plumbers flux.

If you have enough cable then you can cut off the lug, strip back the wire and replace the lug. I might still solder (with decent flux) unless you have a suitable tool to make the crimp. Another reason for soldering is the cable will likely be oxidised some distance from the lug.

Another alternative is to keep cutting and stripping the cable back until you can see bright copper, and then splice in a new length.

Reply to
Fredxx

Ok.

So you are suggesting it's the ring terminal on the end of the engine bay loom that has heated the stud it bolts onto and not the other way round. Eg. the 'guts' of the connection fitting going hr internally and heating itself and the end of the loom?

That would suggest you do suspect the ring terminal on the end of the engine loom / feed. I guess I could test that by using some heavy duty crock leads to connect the ring terminal directly to the glow plug bus and see if that ring terminal still gets hot?

I do have a crimping tool and I think they recommend you 'don't' solder (or also solder), especially in areas of reasonable vibration (like round a diesel engine ) as soldering makes the cable rigid and more susceptible to fatigue / fracture?

Understood.

Understood.

I think Fords solution to this problem is a new glow plug loom (£14) and a new engine bay loom (£500). ;-(

The point with our problem is even if we have an issue with the connection between the cable, ring terminal and it's threaded stud, said stud is now very loose in it's mount and therefore not making a reliable connection in any case.

I guess a test would be to replace the small glow plug bus first and see if the terminal stud thing still got hot in use.

Cheers, T i m

Reply to
T i m

I'm aware of that, it depends on long you want the repair to last. In my case it lasted years, when the car was then sold.

I'm unsure of the wiring, is the glow plug loom from this lug to other glow plug terminals too?

I wasn't aware the glow plug terminal was itself loose. I would certainly replace it as a matter of course. You did say you got 0V at the terminal before the car had started? (I assume before any timer switched off the glow plug drive?). So I might still believe the wiring is an issue.

Reply to
Fredxx

As long as possible and I'm told that would mean without soldering but possibly with being sealed with something (heatshrink).

Gdgd.

Yup. If you can see the pic, the feed comes in from the engine bay loom (bottom of the picture) and bolts onto a stud. That stud seems to have been moulded / potted into a plastic bracket that is bolted to the block. From out of the bottom of this block comes a heavy (red) cable that daisy chains across the tops of all 4 glow plugs (and why I referred to it as a 'bus').

Not that I can see so far.

'It'? If you mean the small loom that includes and goes from the connector block thing and to all 4 glowplugs then yes, unless I cut that block thing off the end and re-join the wires a different way.

I did.

Correct ... although it deed seem to continue feeding power to the glow plugs even after the engine was running which I understand is what they do these days (to manage emissions).

Oh, I *know* the wiring is an issue (if not the only one), the question included, if it isn't the only issue, am I going to wreck a new loom (like if a glow plug was low resistance and drawing more current than it should etc) if I simply replace such?

I have no real experience with diesels and so wasn't sure of the fault modes of such things (like glowplugs).

I have read of someone replacing all 4 glowplugs and the connector thing still smoking / melting. ;-(

Cheers, T i m

Reply to
T i m

A coincidence but I've just changed my glow plugs as it was a pig to start with seemingly one plug working. Once a second cylinder fires it can continue under its own steam.

Where is the overheated connector? Is it on the local glow plug loom, or the main loom. I assumed the glow plug loom? If so for £14 I would replace it. I have never known glow plugs go low resistance, all the ones I know went high to o/c.

Reply to
Fredxx

Even with all 4 glowplugs disconnected his Transit Connect seems to start ok?

Can you see the picture? If you look at the stud where the ring terminal is bolted onto the stud, you can see the stud leaning forwards (towards the bottom of the picture) and if you were to lift it upwards, it would come out easily.

Former.

It is.

Apparently, not actually tried to get one yet.

As would / will I ... or bypass it etc.

Ok, that's good to know, ta. ;-)

Cheers, T i m

p.s. I don't think I can get in there but I was thinking I could use a / my DC current clamp to measure the current on the glow plug bus to see if they are all working or not. In theory you would see the 4x current on the main feed, 3x on the lead between 3 and 4 etc.

Reply to
T i m

A modern Di diesel will start pretty well without glow plugs but the emissions will be much higher until the engine is fully warmed up. Modern glow plugs stay hot for some considerable time after starting to reduce emissions.

An older indirect injection engine relies much more heavily on its glow plugs for starting.

Tim

Reply to
Tim+

I wouldn?t solder. I have experienced this fracturing at first hand when I mistakenly soldered a starter motor connection for an outboard.

Tim

Reply to
Tim+

Understood.

Yeah, like the old 1.9 Pug lump I had in my Rover 218SD. It might start with only a couple of seconds of glow plug but it would rattle and clunk like a bag of spanners for a good few seconds till it warmed up a bit.

Cheers, T i m

Reply to
T i m

I think it all depends on what the joint / cable is exposed to as to if it's 'ok' or not.

Like ... I understand in the narrow boat game a soldered auxiliary battery terminal (particularly) is very likely to fracture, *because* of the frequency of vibration you typically get from a single cylinder slow revving diesel engine. This would really be exaggerated if the cable coming off the terminal was not supported and it's mass happened to get it in resonance with the engine vibration.

When we built the kitcar around 30 years ago I crimped / soldered many many connections and none of them has failed, including all the main starter leads.

So, if you crimp and solder or even just solder and remove all the flux and glue-heat shrink / self amalgamating tape and make sure the cable is supported properly ... or allowed to flex away from the end of the cable ... the chances are things will be ok?

When I was an electrical apprentice during the summer holidays from technical college I 'soldered' some lugs on the end of a very heavy duty lump of SWA and did so with a couple of blowlamps!

I've also soldered (only) hundreds of RC model connectors over the years and really can't remember one ever failing *because* it was soldered and not crimped. But then I generally use very flexible cable and if the connector type allows, heat shrink the end of the cable and the soldered joint with the glue lined heat shrink that acts a bit like a strain relief sleeve.

Cheers, T i m

Reply to
T i m

Are you saying that the stud is loose in it's threads? If so that will cause the overheating and damage the cable to terminal connection with the heat.

I don't like using solder in a connection that's clamped in some form as the solder is soft and can deform under pressure which loosens the connection and then it overheats.

Reply to
rp

Sort of. I'm guessing the lower half of the stud was originally pushed into a 'socket' that might be crimped onto the cable going to the glow plugs and then set / potted in this plastic mount. I think the connection between the lower half of this post goes (that I think is unthreaded) goes h/r with the socket / connection that then causes it to heat and then melt the mount and insulation on the loom cable etc.

If I get a chance I'll pull the post out of the mount again and take a picture of it.

Understood.

If I am making smaller crimpable connections I crimp the connection

*first*, then solder, so the solder shouldn't impact the strength of the crimp part of the joint at all should it?

Cheers, T i m

Reply to
T i m

No, if it's a good crimp them the solder will just coat the wire and stop it oxidising and give a good electrical contact.

In the 80s I used to come across a lot of office computer stuff where the supplier had to fit a mains plug and they often tinned the wire before fitting it. I'd find the plug was quite warm and stripped the wire back to clean copper and refitted the plug and that cured a lot of intermittent problems. Now everything has to have a crimped and have plug molded on so it's not an issue.

Reply to
rp
[...]

That's considered very bad practice, at least in the electrical industry. (Of which I was a part, for all my working life.)

Primary reason is obviously the solder wicks into the wire, and creates the possibility of a stress fracture at the junction between the wire and the lug.

There are other reasons that are to do with adversely affecting the cold weld created by the crimp process.

A *properly* made crimp, with the correct size lug, and made with the lug manufacturer's tool, is several orders of magnitude better than a soldered joint in every respect.

Chris

Reply to
Chris Whelan

Ok ...

Assuming the wire ever moves or tries to move in comparison with the lug presumably? The keyword of yours there being 'stress', so no stress no fracture?

How though?

Quite possibly, but you may have also highlighted the key weaknesses ITR(d-i-y)W?

Q. Given that the crimp must crush the wire strands to some degree (or there wouldn't be any 'cold weld', couldn't that also weaken the wire strands and right where any movement would occur?

I think if I took two identically sized wires going into two identically sized lugs, one crimped and one soldered, I feel the crimped one would allow you to repeatedly bend the wire very near the lug (work hardening the copper) it would break right next to the lug.

A soldered connection would tend to spread the 'stiffness' of the interface from the lug out along the cable, tapering that transition to some degree?

I'm not arguing your RW experience Chris, just that I have been soldering connections since being trained by BT and I can't remember

*ever* experiencing any failures in the cable to lug interface (and of course many connectors can only be soldered), like the hundreds of RS232, X21, V35 cables I've made over the years?

Most of the connections on the mobile disco I built were (only) soldered ... and exposed to quite a bit of vibration in use and in transit, again, never an issue?

But maybe I was also sensitive to such connections and supported the cable away from the lug and restricting the likelihood of stress fractures etc?

Cheers, T i m

Reply to
T i m

Solders creep under stress, copper doesn't. Therefore it is bad practice to tin the ends of wires which are then clamped in a screw terminal.

It is good practice to use ferrules.

Reply to
Fredxx
[...]

Likewise with my experience of crimped connections. I've used crimps on cables as small as 0.5mm2 csa, and on 3-phase distribution cabling up to

300A rating. Never a failure.

The industry I worked in had lots of high speed machinery, with a lot of movement and vibration. The environment would have been harsher than in a typical car.

I'm old enough to have been working at a time when crimped connections were 'new', and there was some resistance (!) to them from the older guys. They were all won over eventually.

In the motor industry they still seem to think of crimps as a bodge; that's only because they haven't trained people to use them correctly.

Chris

Reply to
Chris Whelan

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