1. Home
  2. Car Maintenance
  3. DCi works great with all glow plugs defective !

DCi works great with all glow plugs defective !

HI Chaps. So riddle me this.

I've a 2003 Renault Laguna 2 dci(120). About 50k on the clock. Mechanically sound, starts and runs just fine- has done since I bought it two and a half years ago and all regular servicing done by me.

Just for kicks, last night I went out into the garage and put my multimeter across the glow plugs. Every one of them was open circuit. Took a couple out- sooty on the end but mechanically solid. Checked again- open circuit. As sanity check put them across a battery- nothing.

Bought a set of plugs (NGK was all the shop had) this morning and checked them out before I slapped them in. Half an ohm, nice cherry-red tip when put across the battery. Now installed.

So, revelation. With four defective glow plugs, how come the car started fine- even when left outside to freeze in the snow recently, and threw no idiot lights on the dash. I know direct injection needs less heating than indirect, and that heating on this machine is three phases for emissions and cold drivability, but I am flabbergasted it has worked reliably as is. Any thoughts?

Rich.

Reply to
rich
Loading thread data ...

Some modern systems (vectra diesel springs to mind) do not use the glowplugs unless temperature gets below minus 5 degrees C. Mostly the UK doesn't get that cold.

Reply to
Mrcheerful

In the 15 years I've been driving lorries, I have never needed to use the glowplugs on them. Glowplugs aren't necessarily needed to start a diesel - only if cranking wouldn't be sufficient on its own to raise the temperature of the compressed air in the cylinder enough.

Reply to
Conor

Thanks for the reply gents. I guess what with temperatures not getting very much below freezing and the car being direct injection (with a good battery to crank it), the plugs weren't needed. That didn't stop the glowplug indicator on the dash cycling each morning before pressing the starter so the electronics were still going through the motions yet there was nothing to tell me that I have been in trouble had temperatures dropped much further. Ah well, thats 40 pounds gone to refresh the plugs even if I'd not need them for 98% of the weather we get in the south west.

Rich.

Reply to
rich

My Octy TDI 90 doesn't light the dashboard "plug warming" indicator (or it's on too brief) unless the plugs are going to be used when it's very cold.

Reply to
Adrian C

The light on the Laguna doesn't come on for long either- maybe four seconds on the coldest mornings this winter, but my surprise was that even that doesn't seem to have been necessary to start the car at first prod. Anyhow, at least if the car ever fails to start I can't blame it on the plugs!

Cheers

Rich.

Reply to
rich

As others have said, it needs a lot less heating - if any at all, until it's proper cold. The glowplug warning light may simply have come on in conjunction with the self test mode... The Saab used to show the glowplug warning light but only used them when it was "bloody cold" (judged by the coolant temperature). 12 hours wasn't long enough to get the block quite proper cold. 24 hours was more like it...

Reply to
DervMan

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.