Poor cold starting DW8 diesel

[ito]

I’ve had a problem with starting that I have not got to the bottom of, perhaps you might have a suggestion or two?
The vehicle is a 2003 Peugeot Partner van, non turbo diesel, 1868cc. I purchased this vehicle a few weeks ago with the owner stating that he had changed all four glow plugs (which he had) and a new battery 60ah. Mileage is 119K and the oil, air and fuel filters have been replaced last week.
The fault: extreme difficulty in starting when the ambient temperature is below 6 C, first start in the morning (all other starting is ‘on the button’).
How it manifest itself: Churning on the starter after two or three heating sessions of the glow plugs, if I persist, will eventually fire with a great cloud of black smoke (not surprisingly). I park on a slope, and the engine starts instantly in the morning if I bump start with no smoke and a healthy sound to the engine with good tickover.
Actions taken so far:
1. Replaced all four glow plugs (each one checked to see if they glow orange before installation). In non start situations examining the glow plugs shows an unburnt fuel coating.
2. Checked the action of the glow plug relay – A1, timing and voltage output is fine. I know these engines are particularly affected by glow plug failure, even one, but in this case it is not the culprit.
3. Changed the starter motor – I did this because I suspected the starter speed might be just a little slow, but to honest I did not expect a result as this engine (DW8) and its direct predisessors are not over sensitive to starter motor speed variations (unlike the Peugeot Hdi’s) – no result.Checked the cables also at the time of changing, good earth connection present.
4. Changed the battery, it was a cheap make, and although only a few weeks old, at the lower rating of 60ah: Installed a new Lucas 68ah battery – no result.
5. Compression problem: Well, although I have not had the compressions checked (involved and a tad expensive, and anyway if it was I would have to live with the fault!). Back pressure is significantly very low at the oil filler point, the engine fires up with a healthy crack when it does get going, there are no signs of oil leakage or oil mist, and the engine starts on the button at minus C if the vehicle has been left all day but used in the morning! Clean engine bay! I have had much more worn engines of this variety and the XUD type without any significant starting problems.
6. Fuel: There is (by examining the glow plugs) not a sign of underfueling, the engine ticks over and revs as it should and I get excellent mpg without any noticeable smoke with a good amount of power even though it’s naturally aspirated. By the very fact there is no smoke when bump starting and the correct idle speed lets me believe that it is not overfueling. The cold start mechanism on the fuel pump is taut when cold and loose when hot, but to be honest, although it might not be functioning 100% it would only affect the idle speed and might just prevent an instant cold start situation, but would not give such a severe fault as I am experiencing.
Any suggestions?

[Gibbo_Wirral]

I'd suggest a Planet diagnostic and read the live data. You could throw parts at the problem all day long and not get to the bottom of it.

[Peter.N.]

If you are saying that it starts OK when parked on a slope the problem will be air getting into the fuel system.

Peter

[spider]

I too am thinking air ingress. Valve clearances do not usually move on these that often and if they do they close slightly, which will mean it will not start when its warm usually, but it will fire immediately when its stone cold.

The filter bowl on the DW8 is not that dissimilar to the XUD one, in that it has a seal underneath it on the thermostat housing area. Air there could cause issues.

Other issue with the DW8 filter is the silly (sorry but it is) 'band' type clip holding the lid on. Its worth taking the lid off and back on again to check. When the filter was replaced you or they *did* change the seal in the lid yes ?

Having said that most DW8's already have a nice piece of factory fitted clear pipe, can you not see signs of air in that ?

[BX]

The valve theory is the other way round. They miss when cold and run ok hot.
A common problem is diesel leaking back to the tank. This is cured by fitting check valves (non return) in the fuel lines. Most diesel specialists and some auto factors stock them

[wheeler]

The valve theory is the other way round. They miss when cold and run ok hot.

Not if the clearances have gone tight, the TUD5 engines are notorious for this, they start & run no problem when cold but are really difficult to start when hot.

[nametooshort]

I don't know DW8s at all, but if they are anything like XUDs (which they are very closely related to?) then they have a non-common-rail fuel system with no separate delivery pump, relying on the injection pump's transfer pump to suck fuel from the tank on it's own? Like others said its vurnerable to air getting into it.

I guess you can easily identify that problem by leaving it to get really cold (to the point when you know for sure it would start acting up) and then operating the priming pump. Not just a few times but until it offers resistance and then a few more times. This can hurt your hand if it's the almost useless hard plastic squeezy type pump.

If it starts right away after priming then it's a fuel system problem.

Another thing, the glowplug relay. If it was me, i would again let it cool down to the level when you are sure it will start acting up, and then get a piece of thick cable like a jumper cable and jumper the glowplugs directly to the battery for about 30 seconds, an then try to start it. I say this because its not the first time now that I encountered incidents when people measure the voltage at the glowplug relay output and its fine, but then there is a bad connection somewhere along the way and the glowplugs don't get enough power. If you physically power up the glowplugs directly by jumpering one of them to the battery, it will have no choice but to warm up. Then if it starts instantly you know its just a wiring problem.

[BX]

I have never even seen a tud5 so i know nothing about them. However i have come across a number of xud7 and xud9 engines with tight valve clearances. They always missed when cold. However when the engine warmed up they were fine. I just guessed that this was because the aluminium in the head expanded more than the steel in tje valve stems The solution was to remove the shims and bring them down to size on a surface grinder.
I have never yet come across the problem in the dw8. However diesel leaking back overnight is a common cause of cold start problems.
Nametooshort i would regard your suggestions as being on the ball. You are correct as regards the fuel system. However the fuel priming pumps are on a downhill as regards quality and effectiveness. First there was the piston type pump on the top of a CAV 296 filter housing on the 1.6 diesel of the 1970s and on the early xud. Then came the squeasy bulb followed by the useless contraption and oval filter housing on the dw8. The dw8 priming pump and fuel filter housings can cause numerous problems including sucking air into the system as you prime.

[ito]

Some interesting ideas here, firstly though air in the fuel I would discount as the amount of black smoke produced when it does finally fires indicates to me that there is sufficient juice in the system to enable it to fire up if there was not another problem. I will try the wire direct to the battery on the glow plugs next as its a relatively easy test. Why it starts easily in the fault situation on a bump start (I've only got about 30 ft of running before hitting a brick wall!) and then runs with a normal tickover and no excess smoke confuses! Also considered the valve clearances, also using diagnostics, but thankfully there is not much in the way of electronics in this vehicle, thats the next thing to follow up. thanks for your suggestions and time, much appreciated. Sam

[steve18gls]

Fuel pressure sensor ?

[Peter.N.]

When you bump start its turning the engine over much faster so you don't lose as much compression heat. If it starts that easily I would do as you say and check that you actually have voltage on the glow plugs. You will need a fairly thick wire as the plugs draw 60-80 amps.

It has an injection pump so no pressure sensor.

Peter