Quick tale first...

My S reg 306 TD was suffering from smokey starts a while ago. It wasn't 
engine oil; it was light in colour and I could smell chip fat so I 
changed the glowplugs. Well, I changed three of them; one was badly 
rounded off by a previous owner. The smoke had almost gone (just a tiny 
bit on cold starts) so I just left it in but the smoking increased so I 
finally decided to get the plug out and fit a new one, which I did 
yesterday.

The smoking is still there. Only on cold starts. It is fine when warm.

Could one of the ones I fitted in the meantime have failed?
Could the one I've had stored in my toolbox(...) since I bought the set 
of four failed somehow?
Is there a way of testing them?
Could the problem be something else which is causing inefficient glow 
plug operation?


-- 
Abo

On Sat, 23 Aug 2008 09:57:35 +0100, Abo <no@spam.thanks> wrote:

> Quick tale first...
>
> My S reg 306 TD was suffering from smokey starts a while ago. It wasn't  
> engine oil; it was light in colour and I could smell chip fat so I  
> changed the glowplugs. Well, I changed three of them; one was badly  
> rounded off by a previous owner. The smoke had almost gone (just a tiny  
> bit on cold starts) so I just left it in but the smoking increased so I  
> finally decided to get the plug out and fit a new one, which I did  
> yesterday.
>
> The smoking is still there. Only on cold starts. It is fine when warm.
>
> Could one of the ones I fitted in the meantime have failed?

Yes

> Could the one I've had stored in my toolbox(...) since I bought the set  
> of four failed somehow?

Maybe

> Is there a way of testing them?

Yes, if you've got a DC current clamp it's easy, otherwise measure the  
voltage drop on the feed to each plug. If they're wire seperately it  
should be about the same, if they're wired one after the other it steps up  
on each one. Or disconnect the lead to each plug & connect a headlamp bulb  
between the plug & lead.

> Could the problem be something else which is causing inefficient glow  
> plug operation?
>
>


The glow plug relay. Check they're actually getting volts. You can also  
take them out & see if they glow.

In article <g8oje6$1sc$1@news.albasani.net>, Abo says...

> Could the problem be something else which is causing inefficient glow 
> plug operation?
> 
How about not glowplug related at all?
Weeping injectors? Cylinders get diesel weeping in and when left a long 
period it smokes.  

-- 
Conor

I only please one person per day. Today is not your day. Tomorrow isn't 
looking good either. - Scott Adams

Conor wrote:
> In article <g8oje6$1sc$1@news.albasani.net>, Abo says...
> 
>> Could the problem be something else which is causing inefficient glow 
>> plug operation?
>>
> How about not glowplug related at all?
> Weeping injectors? Cylinders get diesel weeping in and when left a long 
> period it smokes.  

Hmm not thought of that one, I'd never done diesel before the 306 lol

-- 
Abo

Conor wrote:
> In article <g8oje6$1sc$1@news.albasani.net>, Abo says...
>
>> Could the problem be something else which is causing inefficient glow
>> plug operation?
>>
> How about not glowplug related at all?
> Weeping injectors? Cylinders get diesel weeping in and when left a
> long period it smokes.

always look at the easy option first, glow plug failure is usual, sometimes 
within months for crap glowplugs.

undo all the glow plug leads, put a jumper cable to each glow plug in turn, 
you should get a healthy crackle as you connect, if you do it is almost 
certainly (99 per cent) ok

Duncan Wood wrote:

> Yes, if you've got a DC current clamp it's easy, otherwise measure the 
> voltage drop on the feed to each plug. If they're wire seperately it 
> should be about the same, if they're wired one after the other it steps 
> up on each one. Or disconnect the lead to each plug & connect a headlamp 
> bulb between the plug & lead.

It is a single feed to plug 3; a common cable then links all the plugs.

>> Could the problem be something else which is causing inefficient glow 
>> plug operation?
>>
>>
> 
> 
> The glow plug relay. Check they're actually getting volts. You can also 
> take them out & see if they glow.

I'm assuming they *do* get voltage, the car starts after one crank once 
the GP light has gone out so it's not actually grumpy starting or anything.

I think whipping them out and checking they glow might be a good next 
step. I guess they earth through the body of the plug?

-- 
Abo

On Sat, 23 Aug 2008 11:01:13 +0100, Abo <no@spam.thanks> wrote:

> Duncan Wood wrote:
>
>> Yes, if you've got a DC current clamp it's easy, otherwise measure the  
>> voltage drop on the feed to each plug. If they're wire seperately it  
>> should be about the same, if they're wired one after the other it steps  
>> up on each one. Or disconnect the lead to each plug & connect a  
>> headlamp bulb between the plug & lead.
>
> It is a single feed to plug 3; a common cable then links all the plugs.
>


Then 3-4 chould be V, 2-3 be 2*V, 1-2=V

>>> Could the problem be something else which is causing inefficient glow  
>>> plug operation?
>>>
>>>
>>   The glow plug relay. Check they're actually getting volts. You can  
>> also take them out & see if they glow.
>
> I'm assuming they *do* get voltage, the car starts after one crank once  
> the GP light has gone out so it's not actually grumpy starting or  
> anything.
>
> I think whipping them out and checking they glow might be a good next  
> step.

If they come out easily

> I guess they earth through the body of the plug?
>



Yes.

Duncan Wood wrote:
> On Sat, 23 Aug 2008 11:01:13 +0100, Abo <no@spam.thanks> wrote:
> 
>> Duncan Wood wrote:
>>
>>> Yes, if you've got a DC current clamp it's easy, otherwise measure 
>>> the voltage drop on the feed to each plug. If they're wire seperately 
>>> it should be about the same, if they're wired one after the other it 
>>> steps up on each one. Or disconnect the lead to each plug & connect a 
>>> headlamp bulb between the plug & lead.
>>
>> It is a single feed to plug 3; a common cable then links all the plugs.
>>
> 
> 
> Then 3-4 chould be V, 2-3 be 2*V, 1-2=V
> 
>>>> Could the problem be something else which is causing inefficient 
>>>> glow plug operation?
>>>>
>>>>
>>>   The glow plug relay. Check they're actually getting volts. You can 
>>> also take them out & see if they glow.
>>
>> I'm assuming they *do* get voltage, the car starts after one crank 
>> once the GP light has gone out so it's not actually grumpy starting or 
>> anything.
>>
>> I think whipping them out and checking they glow might be a good next 
>> step.
> 
> If they come out easily

Well, you need to take the intercooler off but that's only two jubilee 
clips, three bolts and a retaining screw so no big deal. They should 
come out easily now I've replaced them all except the one next to the 
fuel filter housing, it's a bastard to get the 8mm nut off to remove the 
  DC feed wire...

-- 
Abo

"Duncan Wood"  wrote in message 
news:op.ugb443n4haghkf@lucy...
> On Sat, 23 Aug 2008 11:01:13 +0100, Abo <no@spam.thanks> wrote:
>
>> Duncan Wood wrote:
>>
>>> Yes, if you've got a DC current clamp it's easy, otherwise measure the 
>>> voltage drop on the feed to each plug. If they're wire seperately it 
>>> should be about the same, if they're wired one after the other it steps 
>>> up on each one. Or disconnect the lead to each plug & connect a 
>>> headlamp bulb between the plug & lead.
>>
>> It is a single feed to plug 3; a common cable then links all the plugs.
>>
>
>
> Then 3-4 chould be V, 2-3 be 2*V, 1-2=V

I wouldn't expect the voltage drop on the bus bar to high enough or 
consistent enough to use to check to see what plugs are (or not) working.

>>>> Could the problem be something else which is causing inefficient glow 
>>>> plug operation?
>>>>
>>>>
>>>   The glow plug relay. Check they're actually getting volts. You can 
>>> also take them out & see if they glow.
>>
>> I'm assuming they *do* get voltage, the car starts after one crank once 
>> the GP light has gone out so it's not actually grumpy starting or 
>> anything.
>>
>> I think whipping them out and checking they glow might be a good next 
>> step.
>
> If they come out easily
>
>> I guess they earth through the body of the plug?
>>
>
>
>
> Yes.

"Mrcheerful"  wrote in message 
news:GbRrk.46974$E41.38800@text.news.virginmedia.com...
> Conor wrote:
>> In article <g8oje6$1sc$1@news.albasani.net>, Abo says...
>>
>>> Could the problem be something else which is causing inefficient glow
>>> plug operation?
>>>
>> How about not glowplug related at all?
>> Weeping injectors? Cylinders get diesel weeping in and when left a
>> long period it smokes.
>
> always look at the easy option first, glow plug failure is usual, 
> sometimes within months for crap glowplugs.
>
> undo all the glow plug leads, put a jumper cable to each glow plug in 
> turn, you should get a healthy crackle as you connect, if you do it is 
> almost certainly (99 per cent) ok

Fused jump wire with a 15amp fuse is my preferred method.
Small spark = ok.
No spark = open circuit
Big spark/fuse popping = short circuit.

Next most accuarate method is to use a 30A ammeter (with suitable fuse) to 
compare the current draw/drop on each plug.

On Sat, 23 Aug 2008 21:04:00 +0100, moray   
wrote:

> "Duncan Wood"  wrote in message
> news:op.ugb443n4haghkf@lucy...
>> On Sat, 23 Aug 2008 11:01:13 +0100, Abo <no@spam.thanks> wrote:
>>
>>> Duncan Wood wrote:
>>>
>>>> Yes, if you've got a DC current clamp it's easy, otherwise measure the
>>>> voltage drop on the feed to each plug. If they're wire seperately it
>>>> should be about the same, if they're wired one after the other it  
>>>> steps
>>>> up on each one. Or disconnect the lead to each plug & connect a
>>>> headlamp bulb between the plug & lead.
>>>
>>> It is a single feed to plug 3; a common cable then links all the plugs.
>>>
>>
>>
>> Then 3-4 chould be V, 2-3 be 2*V, 1-2=V
>
> I wouldn't expect the voltage drop on the bus bar to high enough or
> consistent enough to use to check to see what plugs are (or not) working.
>

The drop on the busbars normally obvious enough that you can spot the dead  
one. Thereagain I normally just stick the clampmeter round it.