Engine: D5: - Are my glow plugs knackered?

jackass · Dec 21st, 2009, 12:09

I've noticed this winter that my S60 D5 has been a bit more reluctant to start in the mornings. Then this weekend, with an indicated -4'C on the DIM, it decided to start on somewhere between 3&4 cylinders; gave it a bit of boost and all was happy.

So I've got my multimeter out and tested the resistance of the glow plugs on 1,2,4,5; all showed as open circuit. Is it reasonable that the car would start with at most 1 good glow plug (I didn't test 3 as I wasn't convinced I was measuring anything real and it's behind the inlet maniford) at -4'C; or have I missed something?

The car's done 90,000 miles and is 6.5 years old so I'm not expecting the glow plugs to be in particularly good condition.

rippedoffagain · Dec 21st, 2009, 12:21

If they are open circuit, they must be bust. Their resistance should be very low when cold. On my old Vectra they were supposed to draw 10 Amps each, so at 12V that would around 1.2 ohms. When they warm up their resistance will increase but should never read as open circuit.

bogart · Dec 21st, 2009, 13:24

I believe they are supppsed to have a resistance of around 0.75 ohms at 20 deg C

You could also check out that a supply voltage is reaching them.

jackass · Dec 21st, 2009, 15:52

Thanks for the reponses. I realise they should have low resistance - but car is starting none the less (in some pretty obismal conditions) could it really do that with 1/no glow plugs?

rippedoffagain · Dec 21st, 2009, 16:01

Diesel engines didn't always have glow plugs, they technically don't need them, and the glowies are only active for about 30 seconds at most anyway. The glow plugs are there just to make starting much easier.

Diesel ignites spontaneously when under pressure and at a certain temperature (about 50 degrees C I think). The temperature to achieve combustion is largely generated by the act of sudden compression, but in a stone cold engine it would take a while for enough heat to build up to get combustion. The glow plugs simply speed up that process.

Clan · Dec 21st, 2009, 16:16

did you take the feed wire off each glow plug before you measured the resistance?
If so then they are no good with open circuit .
On modern direct injection diesels as your D5 Glow plugs only come on at very low temperatures . They do stay on pulsing for a while after it has started then for emission purposes ..

RJNEEDHAM · Dec 26th, 2009, 20:55

Not sure about the glowplugs but...... I have ben experiencing poor start from my S80 D5 in the recent low temperatures. All that I have read in this thread is very informing. However, I leave the ignition on for about 20 - 30 seconds before I start up and it fires up ok. Not tested the glowplugs but I soon will do. Cheers. Happy New Year.

chopper_harris · Dec 27th, 2009, 12:18

Get your injectors tested for leakback rates - pound to a penny you have at least one with excessive leakback.

This prevents the common rail reaching the pressure to activate the ECU, hence the prolonged cranking required to build up the pressure (> 10,000 psi).

This test should cost you around £40 at an independent diesel specialist (Less than the cost of one one glow plug).
Don't get it done at a main agent, they will charge you more.

What you do next is well documented on this site

Clan · Dec 27th, 2009, 12:23

dont pay anyone , do it yourself:
Take all the return pipes off the top of the injectors , put some cloth around the injectors to absorb any spill .
get someone to crank the engine ... you will probbaly see one or two injectors leaking excessivly like a small fountain those are the ones you need to renew ....

Saftlad · Mar 7th, 2010, 11:58

Sorry to bring this old topic back up, but with other potential issues to look into, I thought I might as well check this one through too and hit the dealer with everything at once.

Car has been sluggish to start, often taking up to 15 seconds to start in the morning, so I figured I'd check the injectors for leak-back since it sounds like something simple to check for myself.

Can anyone confirm that you just remove the engine cover, then pull the tubing (black - cloth covered) off the injector heads?

I did think at first I'd have to take out the retaining clip and remove the metal section underneath, but the tubing looks to be easier. I have tried to remove one tube, but it seems pretty solidly connected. Perhaps more Weetabix before I try again lol

Dec 21st, 2009, 12:09	#1
jackass Senior Member Last Online: Apr 15th, 2024 20:48 Join Date: Dec 2007 Location: Leighton Buzzard	Are my glow plugs knackered? I've noticed this winter that my S60 D5 has been a bit more reluctant to start in the mornings. Then this weekend, with an indicated -4'C on the DIM, it decided to start on somewhere between 3&4 cylinders; gave it a bit of boost and all was happy. So I've got my multimeter out and tested the resistance of the glow plugs on 1,2,4,5; all showed as open circuit. Is it reasonable that the car would start with at most 1 good glow plug (I didn't test 3 as I wasn't convinced I was measuring anything real and it's behind the inlet maniford) at -4'C; or have I missed something? The car's done 90,000 miles and is 6.5 years old so I'm not expecting the glow plugs to be in particularly good condition. __________________ Current: 2017 V90 D4 Inscription, Twilight Bronze Previously: 2003 S60 D5 SE Geartronic, 16.8s @80mph

Dec 21st, 2009, 15:52	#4
jackass Senior Member Last Online: Apr 15th, 2024 20:48 Join Date: Dec 2007 Location: Leighton Buzzard	Thanks for the reponses. I realise they should have low resistance - but car is starting none the less (in some pretty obismal conditions) could it really do that with 1/no glow plugs? __________________ Current: 2017 V90 D4 Inscription, Twilight Bronze Previously: 2003 S60 D5 SE Geartronic, 16.8s @80mph

Dec 21st, 2009, 16:16	#6
Clan Experienced Member Last Online: Yesterday 22:51 Join Date: Jun 2007 Location: L/H side	did you take the feed wire off each glow plug before you measured the resistance? If so then they are no good with open circuit . On modern direct injection diesels as your D5 Glow plugs only come on at very low temperatures . They do stay on pulsing for a while after it has started then for emission purposes .. __________________ My comments are only based on my opinions and vast experience .

Dec 27th, 2009, 12:18	#8
chopper_harris Senior Member Last Online: Jan 1st, 2022 18:09 Join Date: Jul 2007 Location: Standish	Get your injectors tested for leakback rates - pound to a penny you have at least one with excessive leakback. This prevents the common rail reaching the pressure to activate the ECU, hence the prolonged cranking required to build up the pressure (> 10,000 psi). This test should cost you around £40 at an independent diesel specialist (Less than the cost of one one glow plug). Don't get it done at a main agent, they will charge you more. What you do next is well documented on this site Last edited by chopper_harris; Dec 27th, 2009 at 12:20.

Dec 27th, 2009, 12:23	#9
Clan Experienced Member Last Online: Yesterday 22:51 Join Date: Jun 2007 Location: L/H side	dont pay anyone , do it yourself: Take all the return pipes off the top of the injectors , put some cloth around the injectors to absorb any spill . get someone to crank the engine ... you will probbaly see one or two injectors leaking excessivly like a small fountain those are the ones you need to renew .... __________________ My comments are only based on my opinions and vast experience .

Dec 21st, 2009, 12:21	#2
rippedoffagain Premier Member Last Online: Nov 16th, 2019 18:20 Join Date: Mar 2009 Location: Yorkshire	If they are open circuit, they must be bust. Their resistance should be very low when cold. On my old Vectra they were supposed to draw 10 Amps each, so at 12V that would around 1.2 ohms. When they warm up their resistance will increase but should never read as open circuit.

Dec 21st, 2009, 13:24	#3
bogart Master Member Last Online: Jan 31st, 2023 09:51 Join Date: Nov 2003 Location: Languedoc Roussillion	I believe they are supppsed to have a resistance of around 0.75 ohms at 20 deg C You could also check out that a supply voltage is reaching them.

Dec 21st, 2009, 16:01	#5
rippedoffagain Premier Member Last Online: Nov 16th, 2019 18:20 Join Date: Mar 2009 Location: Yorkshire	Diesel engines didn't always have glow plugs, they technically don't need them, and the glowies are only active for about 30 seconds at most anyway. The glow plugs are there just to make starting much easier. Diesel ignites spontaneously when under pressure and at a certain temperature (about 50 degrees C I think). The temperature to achieve combustion is largely generated by the act of sudden compression, but in a stone cold engine it would take a while for enough heat to build up to get combustion. The glow plugs simply speed up that process.

Dec 26th, 2009, 20:55	#7
RJNEEDHAM Junior Member Last Online: Jun 24th, 2011 22:27 Join Date: Mar 2009 Location: WOLVERHAMPTON	Not sure about the glowplugs but...... I have ben experiencing poor start from my S80 D5 in the recent low temperatures. All that I have read in this thread is very informing. However, I leave the ignition on for about 20 - 30 seconds before I start up and it fires up ok. Not tested the glowplugs but I soon will do. Cheers. Happy New Year.

Mar 7th, 2010, 11:58	#10
Saftlad Member Last Online: Jan 27th, 2023 22:27 Join Date: Feb 2010 Location: Taunton	Sorry to bring this old topic back up, but with other potential issues to look into, I thought I might as well check this one through too and hit the dealer with everything at once. Car has been sluggish to start, often taking up to 15 seconds to start in the morning, so I figured I'd check the injectors for leak-back since it sounds like something simple to check for myself. Can anyone confirm that you just remove the engine cover, then pull the tubing (black - cloth covered) off the injector heads? I did think at first I'd have to take out the retaining clip and remove the metal section underneath, but the tubing looks to be easier. I have tried to remove one tube, but it seems pretty solidly connected. Perhaps more Weetabix before I try again lol

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)