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my 406 diesel turbo(N reg) won't start in cold weather. new glow plugs changed last march 08. when i spray cold start, it starts and works all day. in summer it was ok. only since last week, as the weather turned cold, it won't start. relay is ok as there is voltage and it cuts off after about 76 to 7 seconds. same problem last winter as well. hence, the reason for changing the glow plugs. after new glow plugs changed, the weather suddenly changed to warm. hence, all summer no problem. now it is cold, it won't start. please help. what can be the reason. thanks.

Hi
Is this a 110 HDi or 99? Your on the right track - do you wait a few seconds before turning over? Is the battery up ok? A few things you could try - if the compressions are low on a couple of cylinders or all, you need to test. You can do it the lazy way by attaching a voltmeter to the battery and noting if the fluctuations are equal - or attach a clamp on ammeter to the battery lead note the fluctuations. Or remove the injectors and test with a compression tester.
Check your fuel lift pump pressure and the fuel filter - it may be that your not getting the fuel flow that is needed for a richer injection when cold and stops the high pressure pump getting enough fuel. I just wonder if it is running ok when warm.
Seee how you go with this.

Being an N reg this will be the old school XUD motor (1.9td) or even the 2.1 12 valver perhaps.

It would help to know the mileage as if it's very very high it may point to the fuel pump.

I'd instantly say glow plugs but I know you've changed 'em but are you sure they're getting the electrical feed for long enough etc? are you sure they actually work? not sure if you can do this safely to your engine (can't see why not) but have you tried boshing a 12 volt feed straight onto the bus bar of the glow plugs using a decent gauge wire from the battery and then running round to flick it over on the key? I used to do this on an old Nissan diesel at work!

Hi
If this is fitted with an inline injection pump then the following should be checked in order - 1, lift pump 2, fuel filter,3 air ingress. If fitted with a rotary - 1, Filter 2,air ingress,3 lift pump. Although most are fitted with Auto bleed, tiny ingress of air can still cause problems but not enough to stop it running when warm. Secure all pipe fittings and check for cracks or chaffe. Air ingress, it has to be said, is less when lift pumps are fitted in the tank since it would all be pressurised up to the injection pump. However, if the filter starts to block up restricting the flow the injection pump creates a vacuum and that's where air can get in - between the filter and injection pump. Rotary pumps are well known for hunting when filters are blocked because there is just one plunger doing the injecting and it has to work very hard relying on the lift pump to fill the injection chamber quickly. Keep checking. Rotary can be refered to as a DPA - distributor type. Tell me which it is.

logintooth....thanks, but your advice is too technical for me to follow as i do not know much about cars.

thanks welton. it is 1.9. mileage is 54k.what is bus bar please. and please explain in layman language. thanks

54K miles seems very very low

Anyway, a bus bar is the electrical rail to which each of the 4 glow plugs connect too for their power supply. You can usuall frigg up a heavy-ish wire straight from the battery positive and touch it to the bus bar itself to "liven" all the plugs up.

Thing is I've only ever done this to a really simple old Diesel and I'm not too sure if you should give it a go (especially if your not experienced) as I don't know if you'll affect something else like a relay, timer or fuse etc. I haven't enough knowledge of your engine to confirm either way I'm afraid but someone else on here should.

If you're not too sure then you may be best to get it do a Diesel Specialist and preferably one which comes recommended! if you tell us whereabouts you live then we may be able to suggest somewhere.

One other (long shot) is that you do have a keypad immobiliser fitted to yours and these do play up! most on here have disabled the keypad by giving it a command (somthing like C-1-C or whatever, mjb on here knows). I know it sounds silly to associate this with the cold weather but you never know and it would be worth a try as it's free!

Welton wrote:One other (long shot) is that you do have a keypad immobiliser fitted to yours and these do play up! most on here have disabled the keypad by giving it a command (somthing like C-1-C or whatever, mjb on here knows)

mjb does not know...

...but it's in the 406 handbook

I reckon he'd be ok just testing the supply with a meter (one end on the glowplug connection, the other on a decent earth, e.g. the battery -ve terminal), just looking for how long the power is being supplied. Hell, even a test lamp will do. Shorting it down to the battery will probably result in scarey fireworks

The other thing is what Longintooth says, maybe there's a slight air leak and the colder weather is showing it up... Not sure how to test for this but looking for frayed pipes on the injectors and damp patches (No, not those sort of damp patches Welters ). Btw Longintooth, you really need to talk down to us ten-thumbed clods

steve_earwig wrote:Btw Longintooth, you really need to talk down to us ten-thumbed clods

Oh we're not bad for a bunch of DIY mechanics Steve

Hi
Sorry guys I got a bit carried away - What you guys say about the feed to the heaters is very relevant but I assumed wrongly that our friend knew a bit more than he does. I would be careful how much to suggest to him but there may be others who will benefit from the advice. If the feed was disconnected to the heaters and a seperate current passed direct from the battery to them then, try and start, as welton suggested, this should prove that the heater plugs are ok if it then starts.
If that is the case the feed from the relay that was disconnected should be tested. The simplist way would be to connect an ammeter in line with the feed to indicate that the current is enough to let them glow/ heat up. I'm not sure what the exact amperage is but if it is around 20amps that would be enough to do the job. If it's much lower say 5 amps, that would not be enough to start in cold weather bearing in mind that when the starter is turned it robs the heaters of current so making it worse. The problem with other methods using a lamp etc is that 5amps would be enough to light it up but it needs a lot of amps to make a glow plug/s heat up. That being the case a closer look at the earthing points of the wiring to make sure they are a good connection. This is similar to what you would see when you get a bad earth on a rear light when flashers and stop lights are operated together and they all go dim. In this case it would be the relay feed and or earth that's bad or the relay generally - not the glow plugs. Sorry it's a bit long winded.

To ensure the fuel is not restricted from the filter open the bleed screw on the pump and manually pump the fuel using the lttle pump plunger on the filter housing to pump fuel - you can try just turning the ignition on (Don't start the engine yet)and see if the fuel flows well with that only. To check for an air leak - open the bleed screw on the pump and watch for any sign of air coming out with the fuel. Failing that, fit a flexible pipe on the end of an injector pipe and put the end in a jar filled with fuel. Then get someone to start up whilst watching for any minute bubbles rising up from the pipe end once it's bled the initial air out of the pipe of course. Since there is no pressure in the injected fuel it will be safe to handle the pipe - don't try this with a common rail. Don't do it if you are unsure of what I'm saying. Oh and wear some protective gloves cos fuel stinks and it will give you other probs if you have allergies. The thing about diesels
is they are so simple and uncomplicated even I know a bit about them - get the fuel going in ok and they will run. My money is on the heaters in this case.