Smokey Xm, Smokey XM when starting

[jackyboy]

My 2.5td has started playing up. After playing golf I had trouble starting the car and it coughed and spluttered with lots of smoke coming out. After revving it for few minutes it seemed to clear and drove home fine. Next time I tried to start it the same thing happened. Once it is started and revved up it seems okay, though it does seem to have lost a tiney bit of power inthe lower revs. Once running it doesn't misfire or smoke. The car has done 68k from new, any ideas????

[Peter.N.]

Glow plugs or associated ciruitry would be my first guess. I assume that the smoke is bluish white which denotes unburnt fuel, the engine will usually run unevenly when cold if one or two glow plugs have failed, but if its difficult to start and then runs evenly, its probably a failure of the relay or associated wiring. Does the glow plug light come on and do you hear the relay drop out after about 20 seconds? This will usually be accompanied by a slight increase in the brightness of the panel lights.

Peter.N.

[jackyboy]

The glow plug light does come on then go out as normal, I will need to check for the change in brightness later on. I will come back to you after that.

Thanks for your help. (I don't know how I'd manage without the people on this site!!!)

Cheers

Jim

[xmexclusive]

Hi Jackyboy

If it has not already been cut out of circuit the diesel pre heater is the most likely cause as these go porous with age and let air into the system. If you have starting trouble again try pumping the manual fuel pump on the top of the fuel filter and see if this makes starting easier. If so then check out that the feed pipe is direct and not via the heater before you look at the glow plugs. There is a self help on cutting out the fuel heater on the site.

Regards

XMexc

[onthecut]

Hi Jackyboy.

Not related (I hope), but don't forget that at 68k, you're getting very close to belts change time. Well done on finding such a low miler.

Mike.

[DrTim]

Is it (belt change time) 75k or 10 years on the diesels like it says in the handbook for my S2 petrol car? If so, I wonder how long jackyboy's car went between manufacture and registration?

[jackyboy]

Been trying the car again today. Blue / white smoke when starting, takes 2 or 3 goes to get it started then it is very lumpy until it gets warm. It doesn't cut out or anything and idles fine.
Being a bit on the dim side, I don't fully understand the function of the glow plugs. I know that they heat up when you switch the ignition on but once the car is started I thought that was their job done. Would faulty glow plugs make it run lumpy for a while after the car has started?

[onthecut]

Hi Dr. Tim;

My reading of the handbook for 2.5s is 72k miles for the belt change, after about 1995.

Mike.

[onthecut]

PS.

Yes, on many diesels, the glowplug control is set to give continued glow plug function for a short period after starting to enhance cold running smoothness.

Mike.

[Peter.N.]

As mike says, the glow plugs continue to aid combustion while the engine is still very cold to prevent misfiring, but - if you have a faulty one (or two) the engine doesn't start firing on those cylinders until the compression had produced enough heat. The glow plugs are quite easy to check, if you can disconnect the leads, check the resistance to earth from each plug connection, it should read very low, something around one ohm, if it reads very much higher, or not at all - u/s plug.

Peter.N.

[techmanagain]

Having very recently suffered in exactly the same way as you have, I can say with a fair amount of certainty that the preheater relay is faulty. This is mounted ay the front of the battery and probably has the name Cartier printed faintly in blue on one face. It is not (thankfully) expensive at under £25 and will cure your woes completely. Trust me, I've had 4 XMs!
In the meantime, lift up the relay and turn it over. A thick insulated wire touched for 5 seconds between the two threaded terminals will get you started perfectly. But the wire may get hot so handle it with a glove or some other heat insulation; the alternative - and much better - solution being to lever off the relay cover and press the springy contact inside for the same 5 secs. There will be no heat and no possible damage to the ECU. This will give you time to order and receive your replacement.

[bigjohnh]

Hi everyone,

It is worth testing the relay before forking out 25 quid. Either if you are electrically literate a bit of poking around with a voltmeter will prove a lot, for example is 12volts getting to the glowplugs. If you are not put your hand on the relay and get your glamourous assistant to turn the ignition on and off a few times, the relay will be felt to click if the coil is working and the contacts moving.

John

[Ciaran]

Aha the good old wire to glowplugs job. Had to do that every day for about a week when my ignition switch died! (then use a jump lead to trigger the starter, but thats another fun story!)
I used the earth, live, and neutral wires from an old lamp flex, twisted together to distribute the load a little... the wire still glowed red hot and smoked while operating the plugs though!
The warning about being careful handling the wire is a good one to heed

[xmexclusive]

Hi All

I am surprised at the emphasis on Glow plug faults as a diesel XM with the injection system in reasonable condition should not need you to wait for the glow plugs to start at the temperatures this time of year in the UK. There is another regular problem with the feed wire to the glow plug relay. This goes brittle and high resistance with use over time.

Regards

XMexc

[techmanagain]

With respect, you could take the connector off the relay and try it for yourself. You would find the very symptoms he has suffered - as I have also.!
I shall lokk forward to the solution in this case with interest.