Daddylonglegs
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| posted on 16/6/10 at 12:09 PM |
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Diesel Question
Hi all.
Some time ago I posted a query about a Disco that was running rough and chucking out white smoke (unburnt diesel not steam).
I've just had the head pressure tested and they found a leaking core plug at the rear of the head (explains where my water was going over time)
and also it needs skimming.
Would the warping cause uneven or no burn in the bores? I just want to try and see where next if this doesn't cure it.
JB
It looks like the Midget is winning at the moment......
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mad4x4
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| posted on 16/6/10 at 12:12 PM |
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Warping could cause non buring of Fuel as you cvould have a link between Water jacket and Bore or Bore and Bore thus this would lower compression
enough to not burt fuel.
Other place to look on a diesel is Rings. If they don't get a good seal you'll loose compression
Scot's do it better in Kilts.
MK INDY's Don't Self Centre Regardless of MK Setting !
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jambojeef
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| posted on 16/6/10 at 01:08 PM |
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Could be the head being warped I guess but having experienced this on our 200tdi Disco it was the fuel pump timing.
You can check the fuel pump timing on the 200/300 tdi engine by rremoving the little plate on the timing belt cover and place a drillbit / pin in the
hole and checking tdc marks line up ok.
One more low cost thing to check and rule out!
Geoff
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Daddylonglegs
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| posted on 16/6/10 at 01:40 PM |
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jambojeef, timing belt was replaced by my mechnic some time ago and he double checked the timing. But I agree with you that the timing may be the
issue.
I suspect that the Injection Pump timing is not being advanced when the throttle is pressed as it should. I have had several 'discussions'
with people regarding advancing of the IP timing, the argument seems to be that there is none. However, when I talked to an engineer who is going to
check the injectors for me, he agreed with me and said that all diesels have some form of timing advancement. On my EDC model, there is an
electrically controlled unit that is supposed to advance the pump as the throttle is pressed and he seems to think this is another possible area of
issue.
JB
It looks like the Midget is winning at the moment......
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skinned knuckles
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| posted on 16/6/10 at 02:24 PM |
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anything that significantly reduces the compression in a cylinder will cause no ignition of the air fuel mixture, so a warped head, knackered head
gasket, nackered valves etc are all a consideration but as stated its probably a pump timing issue unless the head is VERY warpedand this would
display irself with other symptoms too.
A man isn't complete until he's married, then he's finished
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mad4x4
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| posted on 16/6/10 at 06:12 PM |
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You do a compression test on each cylinder to see if any cylinder is low compression.
Scot's do it better in Kilts.
MK INDY's Don't Self Centre Regardless of MK Setting !
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Daddylonglegs
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| posted on 16/6/10 at 09:02 PM |
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compression test was done a while back after cambelt was changed.
I'm picking the head up tomorrow and getting the injectors checked too. Once I've put the thing back together I'll give it another
go. If there is still a problem I'm going to try the IP.
It looks like the Midget is winning at the moment......
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T66
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| posted on 16/6/10 at 09:04 PM |
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Rough running can also be caused by faulty injectors, ie caked up nozzles, poor spray pattern or out of calibration.
This will give you the over fuelling symptoms ie runs like a bag of hammers & white smoke.
When were the pump & injectors last serviced ?
The rotary pumps I played with (trucks) all had some element of manual adjustment on the mounting studs. The advance mechanism could be mechanical
advance of the cam ring, using weights or manual cable.
If its been fitted out of kilter from where it was previously, and the injectors are thick of cake, you will hic and fart for England.
Compression testing is essential.
With the engine running , crack the fuel feed to each injector one at a time and try and isolate the dodgy one. If you think one is a culprit, swap it
with another one and isolate them individually again.
If this doesnt work pull all injectors one at a time and carefully inspect.
You can have a go at spill timing the injector pump if you suspect it is out of kilter.
Is the engine a high miler ? and is low compressions a possibility ?
If not suspect the pump/injector calibration/timing.
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