ZD30 CRD Cold Start Issue with white smoke

[Hodge]

Not sure about the CRD'S but with the di's, the light turning off on the dash doesn't mean the glow plugs are off. The glow plugs actually stay on for a few minutes after the car has started.

Yeah that's right, and some of them had a ceramic tip burn off, and bounce around in the engines internals, not sure which model it was though ? Some folks installed a manual timing kit or something.

[my third 256]

x2 with growler glo plugs knackered or relay
sonds like its using compression to fire diesel
hence white smoke (unburnt fuel)

[Flex]

How would I go about testing my glow plug relay or glow plugs themselves?

[my third 256]

multi meter take out and check one lead to top one to bottom and see if you have a circut

[Flex]

I've found a trick to my problem, basically turn the car to ignition wait for the glow plug light to go off (after about 2-3 seconds) then start the engine. Starts every time with no issues.

[happygu]

I've found a trick to my problem, basically turn the car to ignition wait for the glow plug light to go off (after about 2-3 seconds) then start the engine. Starts every time with no issues.

Flex,

You are now doing it correctly, as you are meant to wait for the Glow Plug Light to extinguish before proceeding with the starter. The Glow Plugs will rapidly preheat the combustion chamber which helps the diesel to self ignite under compression - remember there are no spark plugs like a Petrol motor which initiate the combustion process. Cold diesel is very hard to get to do anything at all - it is not like Petrol where you throw a match at it and it goes wooosh. The heat assists the self-combustion process by raising the temperature of the diesel.

From Wikipedia.....

Gasoline (petrol) is a fuel for use in a spark-ignition engine. The fuel is mixed with air within its flammable limits and heated above its flash point, then ignited by the spark plug. To ignite, the fuel must have a low flash point, but in order to avoid preignition caused by residual heat in a hot combustion chamber, the fuel must have a high autoignition temperature.

Diesel fuel flash points vary between 52 and 96 °C (126 and 205 °F). Diesel is suitable for use in a compression-ignition engine. Air is compressed until it has been heated above the autoignition temperature of the fuel, which is then injected as a high-pressure spray, keeping the fuel-air mix within flammable limits. In a diesel-fueled engine, there is no ignition source (such as the spark plugs in a gasoline engine). Consequently, diesel fuel must have a high flash point and a low autoignition temperature.


Mic

[threedogs]

Not sure about the CRD'S but with the di's, the light turning off on the dash doesn't mean the glow plugs are off. The glow plugs actually stay on for a few minutes after the car has started.

I was told when the glow plug light went off it was time to start the engine, yes/no?

[Hodge]

It's standard practice to wait till light is off before cranking. I've had this drummed into me ever since I started being around diesels. I'm pretty sure even the manual says so too.

But as mudski said, when the light goes off , they're warm enough to start the engine , but plugs remain on for a little while longer. Im pretty sure the time is reduced greatly on the common rails compared to Dis.

Sent from my S4 using Forum Runner

[threedogs]

Plus there is a glow plug mod from memory that cuts down the time the plugs are glowing.
there was a thread recently on it