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Dutchroger

Active Member
I have a n reg disco with 116K on the clock. Over the last 6 months it has been a bit of apig to start. It always used to just start straight away on the turn of the key no waiting for glow plugs. Then almost overnight it got really poor.

I have done the fllowing to no avail.

New glow plugs
new spill overs
new fuel filters.
new temp sender on top of the engine.
Thrashed it to try and clear it.
run fuel cleaner through.
There is no oil in the water and water in the oil.
No appreciable loss of power
no reduced fuel economy (400 miles to a tank)
No black smoke
No white smoke except on start up if I try it with out running the glow plugs 3 times.

I have now eliminated any fuel problems. The way of starting it is to run the glow plugs three times it then starts like it used to straight off.

It is driving me nuts as it is likely to be something silly and constantly running to glow plugs is apain. Once it ha started I will not have the problem unless it is standing unused for 8 hrs or so.
 
Temp sender on top of the engine says to me its probably EDC.

With mine ive done pretty much the same as you improved it for a bit and now its being awkward again.

Do you know its not drawing air into the fuel system? A couple of ways to check. 1. Try bleeding the fuel filter it shouldn't need any bleeding so if it takes a while to get fuel out air is coming in. The other way which is more fail safe is to change the pipe from the lift pump to the fuel filter for a clear pipe. If you can see bubbles in the pipe air is getting in so look for damp areas on all the fuel lines.
 
Dutchroger said:
New lift pump fitted
glow plugs are reading 9.4V when on .
Click to expand...
Three cycles of the glowplugs and only 9.4 volts at the plugs. Are the glowplugs good quality? Cheapo's off Ebay often do not work well. Most glowplugs are rated at 11 volts so 9.4V would seem low to me, either the battery, glow relay or the earth bond from engine to chassis may be dropping volts. Finally is the cranking speed good?
 
The transparent fuel pipe is very helpful in checking for air sucking in to fuel system, it worked for me and turned out to be the fuel sender lift pipe in tank was rusted and sucking air , especially my start ups from anything over a few hours was difficult,. Now my disco starts up from winter morning cold circa 3c with no glow plug time. a happy 300tdi is usually an easy cold starter engine in my personal opinion. But certainly a fact is good working glow plugs are necessary for easy cold starting.
 
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I am reasonably happy that it is not fuel. The only but problem I can think of is the injectors. I have toyed with the idea of cylinder head I am semi considering getting it skimed but that seems expensive.
 
as said, 9 volts is too low, cheap plugs wont draw enough current and dont hold a decent amount of after glow.

Decent glow plugs should see 11.5 volts min on a good battery.
 
a 300tdi should start with out glow plugs unless its really cold ,poor battery or fuel leaking back from poor leak off pipe etc would be first ,does it breathe heavy with oil filler cap off ,have you put clear plastic pipe in between filter and front banjo on injection pump, usual cause of poor starting if engines in god condition is air in fuel ,once running pump will sdelf bleed so its unnoticeable until it becomes too much air,but on cranking speed pump cant cope especially if cranking speed isnt as good as could be
 
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jamesmartin said:
a 300tdi should start with out glow plugs unless its really cold ,poor battery or fuel leaking back from poor leak off pipe etc would be first ,does it breathe heavy with oil filler cap off ,have you put clear plastic pipe in between filter and front banjo on injection pump, usual cause of poor starting if engines in god condition is air in fuel ,once running pump will sdelf bleed so its unnoticeable until it becomes too much air,but on cranking speed pump cant cope especially if cranking speed isnt as good as could be
Click to expand...

As you say used to start with out the glow plugs so I done't think they are the problem. As to fuel I have done loads got clear pipes no bubbles. It is weird that if I run the glow plugs 3 times it starts just the same as it used to. First turn of the key. It is an annoying problem because it may be hiding something else.
 
Dutchroger said:
As you say used to start with out the glow plugs so I done't think they are the problem. As to fuel I have done loads got clear pipes no bubbles. It is weird that if I run the glow plugs 3 times it starts just the same as it used to. First turn of the key. It is an annoying problem because it may be hiding something else.
Click to expand...

if you are convinced it isn't the fuel, get it compression tested.
 
trax said:
if you are convinced it isn't the fuel, get it compression tested.
Click to expand...

My next thing to try I am getting to the opinion that it is either compression or injectors. I want to try and sort is as I have rare beast of a n plate 300 tdi that is rust free.

Anyone know a decent trustworthy mechanic to get this done in east London or essex
 
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