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agentmulder

Member Since: 16 Apr 2016
Location: Outer Space
Posts: 1324

White smoke on start up - diagnostic breakdown required

I'm aware there are other topics on the issue out there, but they are a bit scattershot with one line replies like 'MAF', 'check coolant' etc. I'm hoping to make this thread into more of a detailed (bordering on 'for dummies') resource for those of us with this issue.

In my case it's a 2.4 TDCi with @ approx 60,000mi, I'm third owner, cant verify service history, so may as well assume 'not the best' (but who knows really), I can say that since ownership it's been serviced and treated with OCD level. It has the BAS 150 remap and EGR removal (no blank), but smoke was apparent prior to this and it caused no change.

Issue is white smoke on start with cold engine, doesn't last long like 10s or so, but it is quite thick and smelly (awkward starting it in friends driveways when saying goodbye and the exhaust is pointing in the direction of their open door...)

I drained and replaced coolant with new recently, no change, but level still dropping very (very) slowly.

Oil and oil filter changed, loses oil slowly also, no drips visible though.

In NZ we seem to be blessed with good quality diesel (or perhaps a better way to say it is that we have no basis from which to determine which is the best).

What would be the all diagnostic tests I can complete at home within the space of a day (per test) to rule out suspect issues?

turbo?
head gasket?
injection?
thingymabob?
whoozawhatsit?

Keen to nip a bigger problem in the bud...

______________________________________
One related but perhaps non essential question:

Glow plug dash light, does that indicate that a sensor has sensed that the plugs are now warm, or is it simply connected to a timer that goes off when the plugs should be warm?

Also, should note that the BAS RRC programmer has some of the functionality of the GAP diagnostic tools, if that is helpful? Solved the bowel problem, working on the consonants...

11th Sep 2016 12:17am

Alien

Member Since: 18 Jan 2015
Location: Bacchus Marsh
Posts: 230

Glow plugs would be where I'd start.
The clue is white smoke being unburnt diesel clearing once the motor starts to warm up.
Try cycling the glow plug sequence twice before cranking the motor.

The TD5's used to do this in the more extreme cold climates as the only ran 4 glow plugs not 5.

Edit..
Just read the foot note as at first look thought it was a signature.
The glow plug light comes on when required to tell you they are warming up.
Wait for the them to go out and the crack it over.
Inputs will be coolant and ambient temperatures (from memory) and the length of glow time will depend on those values. Cheers,
Kyle.

11th Sep 2016 10:18am

agentmulder

Member Since: 16 Apr 2016
Location: Outer Space
Posts: 1324

Ok, so I turned key three times to the spot just before 'crank the engine' and off again.

Glow plug light came on for what appeared to be the same amount of time each time.

Still smoke...

But the glow plug light is confusing.

If it indicated 'glow plugs glowing' (to the req temp) then why doesn't it cycle on again when I leave the vehicle for a while (and it cools again)

If it indicates 'temperature reached' then why does it come on when I cycle the key in the on/off position 3 times ?

The glow plugs are powered for a minimum amount of time regardless ? Why ? (and then switch off once a sensor senses the warmed area is at the required temp?) Solved the bowel problem, working on the consonants...

12th Sep 2016 10:09pm

hornet

Member Since: 04 Jan 2010
Location: Western Europe
Posts: 361

I translate that explanation from workshop-manual:

The temperature of CHT-sensor is relevant for calculation of glow-time. The lower it is, the longer is glow-time. Maximum is 8s at temperatures -20°C or below. When 80°C or above, no glow-time is needed.
When engine is running, afterglow phase is max. 30s at temperatures -20°C or below, no afterglow phase at temperatures above 50°C.

When you turn off ignition and start again the process is simply reset. The afterglow phase is not indicated by the light. Insofar I do not see advantages starting the glow process several times...

13th Sep 2016 5:15am

agentmulder

Member Since: 16 Apr 2016
Location: Outer Space
Posts: 1324

What I'm saying if is dependent on what is actually going on, so... if (BIG if) the initial glow on time is determined by a 'local' but not perfectly local heat sensor than that is why after three cycles I still get the glow plug dash light showing the glow plugs working...

The heat simply hasn't made it to the sensor yet.

Maybe after cycling x times more it would trigger hot enough (over 80deg), or the glow plug would burn out or battery deplete as there is just too much thermal radiation, conduction to the rear cross member (

) and possibly convection on a windy day to ever get the temperature up at the CHT (like it would do smartly with actual ignition) - who knows ...

I've never touched or seen inside an engine - just going with 'logic'

I'm also unsure how local the glow plugs are to the area the heat is actually required, having them perfectly consistent would be quite an engineering feat - right?

This all plays into the efficacy of the 'cycle them x times for more success' tactic (which could be a hangover from simpler engine times?).

Could all be moot, maybe they're duff and nought is going on and I'm relying on our lovely temperate climate to get me rolling...

I'm googling up how to check them, some hits on fuses and relays under the drivers seat, no hits on how to access them though, mention of a replacement manifold gasket required ? Solved the bowel problem, working on the consonants...

13th Sep 2016 6:46am

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17339

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

I think that you'll find the glow plugs simply provide a hot spot in the combustion chamber to ensure the ignition of the injected fuel charge when the air temperature is low. I don't think that the glow plugs would warm up the CHT sensor if you left them on all day.

As I understand it the process in simple terms is this:

You jump in the car and turn on the "ignition" (I'll call it that, though on a diesel of course it isn't that at all). The ECU springs into life and reads the ambient air temperature and the cylinder head temperature from the relevant sensors.

"Blimey, it's cold today" thinks the ECU. "I'd better run the glow plugs for xx seconds so there's a nice hot spot to aid combustion", so it does this. It turns the light out when it thinks the plugs are hot enough, and by doing so tells you to crank the engine. As you crank, fuel is injected at the appropriate moment into the cylinders. Since the engine is cranking, the charge air in the cylinders is compressed and by being so compressed warms up quite a lot (on a hot engine of course it is the heat generated by the compression of the charge air which ignites the fuel when the fuel is injected), but since when cranking a cold engine the air charge is cold, the ambient engine is cold, and there isn't much charge air anyway because the turbo isn't spinning, the charge air really isn't hot enough to ingite the fuel.

When the injected fuel reaches the hotspot provided by the glow plug, it ignites and a flame front will travel through the fuel vapour cloud igniting most of the charge. However, due to the low temperature of the fuel/air mix, and due to the fact that the flame front originates at the glow plug (which is not optimally located) rather than the injector nozzle (which is) the combustion is not especially efficient and some of the fuel remains unburnt at the time the power stroke commences and conditions for combustion are removed. This unburned portion of the fuel charge is then exhausted causing the white smoke you see. This is exacerbated also by the need to inject a larger fuel charge during cold start in order to ensure that the fuel ignites.

As this process continues, the cylinders and thermal mass of the engine warm up quite rapidly, and ignition is aided by the afterglow part of the glow plug cycle. As the temperature increases, the point of ignition moves from the glow plugs to the injector nozzle as the compressed air charge temperature increases, and the fuel charge (cold start overcharge) is reduced to normal running levels, which both improve burn efficiency and reduce the amount of unburnt fuel being exhausted. Within a few seconds, the exhaust should be fairly clear.

The main point ot note from all this is that the purpose of the glow plug is not to warm up anything in the engine, it is to provide a hot spot which ignites the fuel charge when the heat of compression is not per se sufficient.

As far as I can tell, the white smoke for a few seconds on cold start is a normal Ford TDCi characteristic and is nothing to worry about.

The actual flame dynamics and ignition processes which occur within the cylinders of a direct injection diesel engine are very complex and actually quite fascinating!

13th Sep 2016 8:54am

agentmulder

Member Since: 16 Apr 2016
Location: Outer Space
Posts: 1324

Good post.

I like! Solved the bowel problem, working on the consonants...

13th Sep 2016 10:01am

hornet

Member Since: 04 Jan 2010
Location: Western Europe
Posts: 361

Click image to enlarge

Finally got the wiring diagram for you. You can check them by measuring the resistance. If resistance varies a lot or is zero, you found one (or more) that needs replacement. To check for damage or correct glow you need to remove them. Partnumber LR004377

13th Sep 2016 2:10pm

dorsetsmith

Member Since: 30 Oct 2011
Location: South West
Posts: 4554

measuring the resistance one at a time i.e. one glow plug at a time as 0.6 ohn each as resistors in parallel 1/2 and resistors in series add up i.e. 0.6 + 0.6 + 0.6 + 0.6 = 2.4 ohn

13th Sep 2016 2:41pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20294

I'd back up what BW has said, in cold weather it is a tendancy of the TDCi and fairly shortly will disappear when up to temp.

Glow plugs wise, I use them every start even as warm. And yes, the time they are on does vary according to ambient temperature and engine temp.

There is no good reason at all to rush the starting procedure in my opinion.
(But that's just me!)

13th Sep 2016 6:15pm

agentmulder

Member Since: 16 Apr 2016
Location: Outer Space
Posts: 1324

Thanks for the tips gents.

And yeah, my procedure is: get in, key in/plugs on, seat belt, then crank.

Good use of parallel processing as dash lamp off occurs just as belt is secure

This all assumes I haven't ripped my pants or greased a work shirt getting in, in that case I spend some 'me' time before rolling off. Solved the bowel problem, working on the consonants...

13th Sep 2016 11:53pm

Alien

Member Since: 18 Jan 2015
Location: Bacchus Marsh
Posts: 230

Some very helpful posts that has saved a lot of typing for those of us with fat fingers

Cheers,
Kyle.

14th Sep 2016 3:40am

nickhodgson

Member Since: 08 Dec 2009
Location: Zambia
Posts: 174

Was your coolant dropping before you did the change? If it was dropping then you need to solve that problem as well and they might be linked. Some water in the piston chambers will also give white smoke? What ambient temp are you in?

Do a pressure test on the coolant system and coolant cap. If that does not reveal the leak then do a test on the gasses in the header tank. Do not ignore dropping coolant level - it should be rock solid. 1995 300tdi Defender 90 P/UP
2011 Puma Defender 130 D/C
2000 300tdi Defender 110 P/UP
2015 Discovery 4 SDV6 HSE

14th Sep 2016 2:45pm

nickhodgson

Member Since: 08 Dec 2009
Location: Zambia
Posts: 174

Have you checked the glow plug fuse - the connector on the top RHS of the cylinder head (looking from the front) where the loom connects to the glow plugs can melt and short out.

The radiator cowling can rub a hold in the radiator where they meet. You can remove the top part of the cowling and inspect. Most likely you will see some wear on the radiator fins next to the end tank.

The expansion tank cap can leak through the pressure release and you will typically see stains of coolant on the tank. This is the reason to have it pressure tested. 1995 300tdi Defender 90 P/UP
2011 Puma Defender 130 D/C
2000 300tdi Defender 110 P/UP
2015 Discovery 4 SDV6 HSE

14th Sep 2016 2:51pm

agentmulder

Member Since: 16 Apr 2016
Location: Outer Space
Posts: 1324

Dropping before change yes.

Pressure test, I can think of making a Jerry rigged tester with my compressor, but I don't know what I don't know about that, and what state the thermostat should be in etc. Can you explain how it's done? Solved the bowel problem, working on the consonants...

14th Sep 2016 7:56pm

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