Diesel cold start issues

[johninleeds]

After replacing my battery and cabling my starter turns like a champ... but engine struggles to catch when cold, it's taking at least ten attempts before I get a couple of 'nearly's' that splutter out and then finally it gets going with a plume of white smoke and all is good. It idles/revs happily. If I kill it then try and start again it starts great. Leave it for half an hour or more and I'm back to square one.

I'm suspecting either glowplugs or fuel supply. I thought I'd look at fuel supply first to rule that out. I've done some digging now have a few questions:

1. Should I be concerned that I can quite regularly see a smallish air bubble in the intake pipe to the fuel filter? I've checked the tubing back to the fuel tank and it all *looks* to be in good condition.

2. Is replacing the fuel filter easy? Mine's the screw in type – is it literally a case of screw the old one out and screw the new one in? or is that going to result in diesel going everywhere? Should I remove the filter and the unit it's attached to first? I searched the forum and online but couldn't find any info on changing it.

3. My fuel filter (pictured below) is the screw-in type which has a unit on the top with a number of wires and a relay. I can't find much info about this online – am I right in thinking the unit on top is some sort of thermostat/heater? Mine has been disconnected – the wires have been chopped so there's no power to it. Is this a problem? Would it be easy/desirable for me to switch to a non-screw-in filter?

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[colinthefox]

I can quite regularly see a smallish air bubble in the intake pipe to the fuel filter

There shouldn't be bubbles in this fuel line. It indicates a leak letting air in and you won't see diesel leaking out as this pipe is at lower than atmospheric pressure due to the suction of the pump. A leak at the fuel filter is the prime suspect here.

You might also want to check the back leakage pipes. That's the (usually) braided rubber tubes between the injectors, plus the little rubber cap on no.4 injector. These can perish and let air in causing bad starts. These are a simple DIY fit, and are available for couple of quid from any motor factors.

White smoke often indicates glow plug trouble. As you suggest, you should check that the glowplugs are working. There are lots of threads on here, but I guess OBG will be along soon with the "Check the glowplugs routine" page.

[E D I T] PS I know nothing about the wires on your fuel filter![/E D I T]

[johninleeds]

Awesome, thanks!

Looks like there's three things for me to do then. Thankfully all cheap and not too complicated.

Glow plugs – I'll hopefully have time to test these at the weekend. I found a guide on the forum that looks comprehensive and I've got a multimeter so that should be straightforward enough.

Injector return lines – change these and replace the blank end cap. Just watched a Youtube video and this also looks fairly simple.

Fuel filter – I'll order a new one. I'm guessing since the electrical bits (heater?) are disconnected I should be able to switch to a two-pipe filter (like this) without any bother. I'll be happy to declutter that corner of the engine bay of wires.

p.s. I had a look and the little rubber cap on the no 4 injector appears to have a screw in it. I can't be certain but it looks like someone's maybe added it 'after market'.

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[colinthefox]

the little rubber cap on the no 4 injector appears to have a screw in it.

Aha! That screw may be letting air in around the thread. When the engine is not running, air may well be getting in and gradually draining the diesel system. Then when you try to start, the pump has to prime the whole system every time.

My rule of thumb is to replace the back leakage pipes (and that litle cap) as a matter of routine when I change the cam belt, as they don't last very long.