Disco 2 Cold start problem

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benh999

Active Member
Posts
175
Location
Warwickshire
My disco 2(1999 on 169k miles) from cold can sometimes be a poor starter. Turn key glow plug light goes out and she turns over and catches but doesn't start. This can happen 2 or 3 times and then eventually she fires into life and runs perfect however it does throw out a good black cloud of unburnt fuel. After that she runs absolutely perfect and burns no oil at all and boosts lovely.

Randomly some days it will start first time but most days I have the sequence of it taking a few turns to get her to fire. Is this Glow plugs or is it the injector seals or something else?

regards

Ben
 
jamesmartin said:
sounds more like a fueling issue to me
Click to expand...

Would not think so James firing but not catching is classic of a couple or more consecutively firing cylinders having no heat. The smoke on start burning the excess injected fuel from the cold cylinders also classic of that.
 
to rule out the glow plugs prepare yourself with a multimeter on DC put positive terminal on that thicker yellow/brown wire in front of the fusebox which is alone connected with M6 nut and negative on engine body then ask somebody tuo turn ignition on, if you get 12V then it means the feed is OK... if no feed swap relays R6(glow plugs) with R8(heated screen) and try again... off course that the fusible link must be ruled out first... if still no joy we'll speak then

to check plugs in situ you have to uplug them and measure resistance across engine body and plug terminal and get 0.9 Ohm, if it's greater or open circuit it means it's gone
 
I’m with James – fuelling issue. I can’t be bothered waiting for the light to go out and she will start without a problem. Unbuernt fuel in a cold exhaust wont smoke, will it ? The only time I may have a starting problem is if I have less than a 1/3 tank of diesel but I think this is a FPR issue and she needs a bit of cranking to start.
 
I'm not predicting what it is in reality but the glow plugs must be ruled out anyway IMO before starting complicated troubleshooting of a fuelling issue... not all of them are reacting the same on missing glow'plug action, depends on each's compression too, but the fact that an engine with good plugs starts before the light goes out doesnt mean too much cos they have a post heat operation too and they'll still be under poower after the engine was started regardless of the warning lamp, remove the glow plug relay and make a test if you want... sorry but i dont understand why the black smoke resulted from bad combustion in the chambers would have anything to do with the exhaust tempoerature... classic and "official" symptom of failed glow plugs is difficult cold start and black smoke in all the documents... i'd check them just to make sure even if something else is the problem.
here is from RAVE:
"The glow plugs are a vital part of the engine starting strategy.
The purpose of the glow plugs is:
l Assist cold engine start.
l Reduce exhaust emissions at low engine load/speed.
...
Pre-heat is the length of time the glow plugs operate prior to engine cranking. The ECM controls the pre-heat time of
the glow plugs based on battery voltage and coolant temperature information via the glow plug relay.

Post-heat is the length of time the glow plugs operate after the engine starts. The ECM controls the post-heat time
based on ECT information. If the ECT fails the ECM will operate pre/post-heat time strategies with default values from
its memory. The engine will be difficult to start.
....
In the event of a glow plug failure any of the following symptoms may be observed:
l Difficult starting.
l Excessive smoke emissions after engine start."
 
Last edited:
sierrafery said:
I'm not predicting what it is in reality but the glow plugs must be ruled out anyway IMO before starting complicated troubleshooting of a fuelling issue... not all of them are reacting the same on missing glow'plug action, depends on each's compression too, but the fact that an engine with good plugs starts before the light goes out doesnt mean too much cos they have a post heat operation too and they'll still be under poower after the engine was started regardless of the warning lamp, remove the glow plug relay and make a test if you want... sorry but i dont understand why the black smoke resulted from bad combustion in the chambers would have anything to do with the exhaust tempoerature... classic and "official" symptom of failed glow plugs is difficult cold start and black smoke in all the documents... i'd check them just to make sure even if something else is the problem.
Click to expand...
post heat operation by definition doesnt effect starting,but i check easy obvious first, with a td5 and cold start issues it does depend on how cold
 
jamesmartin said:
post heat operation by definition doesnt effect starting,but i check easy obvious first, with a td5 and cold start issues it does depend on how cold
Click to expand...
off course, but there's no post-heat without pre-heat and the lack of them is black smoke after start, and if let's say the ECM detects open load on the relay's coil it goes to a default which's result is "difficult cold start" ... as i said not necessarily the issue here but worth a check
 
sierrafery said:
off course, but there's no post-heat without pre-heat and the lack of them is black smoke after start, and if let's say the ECM detects open load on the relay's coil it goes to a default which's result is "difficult cold start" ... as i said not necessarily the issue here but worth a check
Click to expand...
with modern direct injection glow plugs arent really necessary excepting emissions,compression is vital agreed ,any engine that needs to turn over a few times to start will produce smoke
 
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