Citroen XM Forum

Hi Russ

Just a thought on testing Glow plugs.
Starting is difficult this weather anyway but it might be possible to test without removal.
Test starting with each of the glow plugs removed from circuit one at a time.
Just remove wires from the top of the plugs in turn.
Some temporary insulation tape for the loose ends may be wise.
With the difficult one behind the pump just take the wire off from the next plug.
If there is a dodgy plug you are currently starting on 3 at present.
If you disconnect the dodgy one it will start as now.
If you disconnect a good one it will fail to start as it will be trying to start on two only.
Work with a well charged spare battery with jump leads across the existing one.
Try the starting like that first as a reference.
You may need an extra plug link wire and a couple of small bolts to do the wiring for this.
Rags round the base of the plugs to catch the dropped link wire nuts.

There is a 3 in 4 chance the dodgy plug can be got at and replaced easily.
If so you could move the glow plug overhaul to better weather.

Fans run on full can overheat this weather.
One of mine does every now and again.
Can hear a relay buzzing just before the cut out.
Think it will turn out to be the relay on the fan speed regulator panel.
If left to cool it drops back in at present.

John

That's a great tip John. Thanks.
I went out and tinkered after lunch, and I found a few of the fuel pipe clips a tad loose. Well they nipped up some more anyway...just thinking of air ingress again. When it's stone cold I'll look at the cold start arm again. Might have mis adjusted itself. And if not, then glow plugs. I have a nearly new set of berus in the other engine.....

I also looked at the fuses in the engine bay and all were perfect. So is the fusebox itself. Didn't get time to investigate the blower itself due to a meeting this afternoon. If needs be, I'll replace the dash panel itself. But considering everything else worked whilst the blower wasn't, I think the blower is most likely at fault...somewhere.

What John suggests (dropping out the glowplugs one at a time) will certainly work. Just don't let the engine run, after getting it to start, because a slightly warmed engine will tend to start anyway, and could be misleading. Sod's Law again.

You can also check that each of the glowplugs is drawing the right amount of current (about 11A each, if I remember correctly) by using one of these...
http://www.amazon.co.uk/Sealey-BT98-10- ... on+ammeter

...if you don't have a beefy ammeter handy. It just clips over the cable in question, and reads the current flowing through it. A 30A and a 75A version available.

Check the plugs one at a time, and look for the one that doesn't draw proper current - hopefully not the one we don't talk about!

Thanks Chris, interesting meter that.

Meh.... Just checked the idle lever at the back of the pump now it's stone cold....and it's back to sitting on hot idle. So no wonder it's not liking starting. That's tomorrow's job then.

The cable pulls it towards the Hot start position, then as it warms, the wax-stat relaxes the cable gradually..

Yes I know, I had adjusted it and it's gone back to resting on the hot idle screw side. It needs to be pulled back to rest on cold idle screw.

Post a pic of this please Russ?

Have just bench tested four used but good Beru glowplugs, from a fully charged battery (alternator not running):
- Single plug connected, instantaneous current 30-40A (first couple of seconds, cold plug)*
- Current fell over 10 seconds to settle at about 15A, tip glowing orange-hot*

Beru quote the following for rod-shape plugs:
- Glowplug still fitted to engine
- Single plug powered up from 12v source (would mean fully charged battery, alternator not running)
- Current should be 15A to 8A after 20 seconds*
- Typical test about 14 seconds, using their own-brand dedicated ammeter

Recommend plugs are not tested in free air, but only when fitted to engine or similar heat sink.
For bench testing, mounting in a lightly tightened vise is suggested.

*The resistance of glowplugs is low (a fraction of an ohm) when cold, and climbs as they heat, hence the falling current.

Thank you so much Chris... I'll log that away.