Diesel Starting problem

MULLEY · Post by **MULLEY** » Wed Oct 20, 2010 12:48 pm

What a surprise, the 1st cold snap of the year & it took about 6 goes before the beast fired up.

The glowplug light on the dash only occassionaly comes on, however i always wait for the relay click sound before starting the car. Normally no issues, except for this morning. The car was turning over, it just wouldnt fire up. Took a 2nd dose of re-heating for it to finally fire up & i used the throttle as well as it was coughing & i'm pretty sure would have failed to start.

I'm hoping someone may have some ideas on what the problem might be? Is it a duff glowplug or 2 possibly? & if it is, are the glowplugs on all the xud engines the same type?

Cheers

Oscar · Post by **Oscar** » Wed Oct 20, 2010 1:23 pm

If it's very cold, I'll run the pre-heat cycle a couple of times anyway. Great big lump of metal will suck heat out of the cylinders very quickly. Might be worth checking the glowplugs though.

MULLEY · Post by **MULLEY** » Wed Oct 20, 2010 8:15 pm

Even last year though, i think i only pre-heated the car twice on only a couple of occassions, no way was it as cold today

Post by **Defender110** » Wed Oct 20, 2010 8:20 pm

Matt

Old thick engine oil can slow engine cranking down causing winter starting issues, some colder climates use thinner engine oil in winter. When did you last change your oil?

MULLEY · Post by **MULLEY** » Wed Oct 20, 2010 8:24 pm

Last week mate

Post by **Tim Leech** » Wed Oct 20, 2010 8:38 pm

Have you fitted some new glow-plugs as of late Matt?

Mothman · Post by **Mothman** » Wed Oct 20, 2010 8:46 pm

I reccon its the glow plugs, mine failed one by one and eventually wouldnt start at all.

Andy

electrokid · Post by **electrokid** » Wed Oct 20, 2010 10:36 pm

The glowplug light on the dash only occassionaly comes on,

Sound like the drive to the glowplugs might be iffy Matthew - if you have a voltmeter stick it + on the glowplugs - on the chassis and perch it on the windscreen to see if the start module is actually delivering volts to the glow plugs - actually wiring a bulb across will tell you as well.

MULLEY · Post by **MULLEY** » Wed Oct 20, 2010 10:59 pm

I'd ruled out the glowplugs as the car has been fine regardless of the weather, if the glow plugs were iffy then surely even in the summer the car would struggle to fire up?

Brian, can you explain in laymans terms exactly which part the start module is? Is this something that a novice can replace or really is it too electrical & i should just get an auto electrician to sort.

I've actually got a voltmeter, can you advise which setting it should be on when testing the glowplugs?

Post by **Defender110** » Wed Oct 20, 2010 11:12 pm

No the engines rely on the glow plugs more as the temperatue drops.
They are very easy to test with a set of jump leads or even by measuring the resistance on them without taking them out. With the negative of a multi metre to the engine block and the positive to the wire connection (with wire removed) it should from memory read .5 - .8 of an ohm. I think if it measures anything more than 1 ohm they are knacked!

sarahjaneking · Post by **sarahjaneking** » Wed Oct 20, 2010 11:16 pm

MULLEY wrote:I'd ruled out the glowplugs as the car has been fine regardless of the weather, if the glow plugs were iffy then surely even in the summer the car would struggle to fire up?

not necessarily, in the summer my old diesel bus would be ready to go almost immediately, in the winter there was a much longer wait for the relay click. I don't know whether on a bx the relay switches due to time or temperature, if it's time you can quite often have to cycle them in cold weather and if they're on the way out a slight drop in temperature can be enough to mean that they're not heating long enough.

hope that makes some form of sense I'm shattered

tc

sarah x

edit: need to type faster

MULLEY · Post by **MULLEY** » Wed Oct 20, 2010 11:19 pm

Sorry to sound a bit dim Kevan, the glowplugs are screwed into the engine, & there are some wire/cables that go from each glowplug but are in effect daisychained? So i need to take these cables off the glowplugs to test each glowplug by itself, or am i measuring the cables at point of connection with the glowplug?

Post by **Defender110** » Wed Oct 20, 2010 11:21 pm

Take the cable off and test just the plug.

MULLEY · Post by **MULLEY** » Wed Oct 20, 2010 11:26 pm

Aha.

Doesn't the glowplug not connected to the wire just become effectively dead, so how can a voltmeter take any sort of reading without there being some sort of power source present? This stuff is all a bit new to me, so sorry for the one million questions.....

Post by **Defender110** » Wed Oct 20, 2010 11:48 pm

You need to set the multimeter to the resistance mode not voltage mode. This is marked with the symbol for ohms , the multimeter has a built in battery to measure the resistance. If a plug goes infinate / open circuit it is duff. If all the plugs are good they will measure very similar to each other. Touch the two multimeter probes together first and measure the resistance of the meter before testing the plugs; whatever this reading is subtract it from the reading you get on the plug to get the correct risistance of the plug.

e.g. If when you hold the probes together they measure .2 then when you measure the plug it reads .8 then the true value of the plug resistance will be .6

Having said this I personally still prefer to take the plug out and do a visual check of any plugs with dodgy readings. With a set of jump leads connected to your battery hold the plug body (not probe) with the negative and hold the positive to the wire connector thread. If the plug is good after 4-5 seconds it should be glowing red.