Glow plug condition

Probably that three of them were kaput. You could test this hypothesis with a multimeter (or bulb and battery) and see if there is any correlation between kaput and sooty.

Why probably? Experience or guessing?

From what I can tell from the picture in my Haynes a certain amount of carbon on the plug is normal.

I have no inlcination to do so. That at least one of the plugs is faulty or at least not been functioing correctly is not beyond doubt given the problem and its cure.

My question is really aimed at those with experince in case the difference in condition is indicative of any underlying cause other than simply plug failure.

A supplementary or alternative question of interest for same is whether a poorly performing plug may be the cause of a smokey start up. I have had a certain amount of smoke on initial startup for around three years. Car is only used about twice a week. Smoke would appear worse when cold weather. I didn't happen to notice any such smoke ths morning but then it is a warmer day also.

But if you did the test then you would have experience and could relay it to the rest of us.

Well it would not give me the answers I am after. What do you think it would tell you that would be useful. You send me the euipment and I'll do the test. ok. ;)

Simple to test. Just use a piece of wire to the top bit (where the feed wire goes) attatch it to the pos terminal on a battery, then touch the threaded bit of the glow plug on the neg terminal. if it dont work nuffin will happen, if it does work you will see the little bugger glow up red.

Then put it somewhere safe to cool down.

Regards Slim.

Well, a while ago when my Renault 18 needed new plugs I remember them being a mix of sooty and clean but I can't remember for certain the correrlation between kaput and sooty. I do know that it was only firing on one cylinder as it started and producing clouds of white smoke until the others got up to temperature.

as a rule if the plug is sooty is isnt working however if you are in doubt connect it to a live and earth and watch the end (care is needed cos it gets very hot ) use jump leads

So it's possible that a single glow plug was starting my engine - with difficulty?

Following that line of thought would two be enough to start the engine normally i.e. without any difficulty, except possibly in the very cold, but with a bit of smoke initially?

I have had a bit of smoke but no real starting problems, until recently, for several years.

It is more than likely that you have had one or more glow plugs faulty for some time, as this would cause some smoke when initially starting. Your problems came when another also died, leaving it just starting on one, which would be difficult in cold weather. You answered your own question really when you say that now you have replaced them all it starts better with little or no smoke.

More likely than what? Do you simply mean Yes and Yes in answer to my questions?

(hit send prematurely)

So in other words you think it is unlikely that I have some other problem to worry about?

I wish someone had suggested the possibility of a faulty glow plug when I asked about the smoke a couple of years ago. The number of times I have uneccesarily gassed passersby.

Damn, I just checked and someone did suggest glow plugs but related it to spluttering starts and, as I have said, there were no such starting problems. Oh well.

That's what I found when I changed mine:

I find it surprising that this is not more commonly known or mentioned. I am sure I am not the only one with a smokey start up who thought and was told that it was probably the sign of a more serious engine problem. How many diesels belch fumes over their neighbours quite unneccesarily.

You will get a certain amount of smoke when starting up anyway. I find if the car is starting on 3 glowplugs or less it's normally evident from the engine note as the cold cylinder bursts into life a second or two later.

On my Renault van the engine was so badly maintained that the glow plugs had actually crumbled into the engine and all that was left was a bit of carbon!