Testing and changing the glow plugs on a TD5

Twinnie · Monday at 23:53

So for the past four years or so my Defender hasn't had to start in anything less than around 15c. Now it's back in the UK and when I went to start it in about 8c it took noticeably longer to get going and it was all a bit rocky until it warmed up. I have a couple of brand new glow plugs so I figured I'd like to take a look under the bonnet and find two bad ones to replace.

I've never bothered messing with them before but I was watching this Britannica Restorations video (link) where it says I can simply touch the end on a 12v positive and look for a spark. To save me taking all the plugs out can I simply pop the connectors off and attach a crocodile clip then brush the other end of the cable to a 12v positive from the battery, leaving the glow plug to ground via the cylinder head as normal?

I only ask because I need the car on Friday and I don't have much time to do this job. Cheers.

miktdish · Tuesday at 10:39

Here's a thread from last year which is full of info.
There is a lot more, try using the 'search' function for TD5 starting or TD5 glow plugs.

changing TD5 GLOW PLUGS?

Having got my engine cover off Ive fallen at the first hurdle :( Is there a knack to getting the leads off the glow plugs? The gap between the engine and inlet manifold is small i can just about get a couple of fingers down but having trouble getting the leads off and i dont want to damage them...

www.landyzone.co.uk

You can test them but to do so properly you need a digital multi meter (DMM) that measures amps.
A good plug draws around 14Amps a bad one much less/nothing.
Using the same DMM you can also measure the resistance this should be between 1 and 2 Ohms, much less and the plug needs changing.

To measure the plugs they need to not be connected to the loom/each other.
The general consensus is that the TD5 really doesn't need glow plugs to start smoothly in the (typical) UK temperatures and that if you have poor starting is is likely something else.

PS, I don't have a TD5 but I see a lot of comment.

Twinnie · 2024-11-20T00:02:29+0000

Thanks. I'd also read that TD5s are good at starting cold but I'd also read other people saying that's not true. I ended up check all my plugs and they weren't as hard to remove as I thought they'd be. I went through them all and found I only had one working properly so I'll try it again when I can find my torque wrench and get them done up properly. I found I actually had 3 new plugs so hopefully I'm all set now.

Stanleysteamer · 2024-11-20T00:08:18+0000

Twinnie said:
Thanks. I'd also read that TD5s are good at starting cold but I'd also read other people saying that's not true. I ended up check all my plugs and they weren't as hard to remove as I thought they'd be. I went through them all and found I only had one working properly so I'll try it again when I can find my torque wrench and get them done up properly. I found I actually had 3 new plugs so hopefully I'm all set now.

I've had a TD5 Disco for 10 years, I hardly ever wait to start it until the glowplug light goes out. I don't live in the coldest part of the country. But I still doubt it is all of your problem. Sadly.

kermit_rr · 2024-11-20T07:59:48+0000

You can use a clamp meter if you have one, around the glow plug loom and work out how many are working before you start looking individually

Twinnie · 2024-11-20T15:11:54+0000

Stanleysteamer said:
I've had a TD5 Disco for 10 years, I hardly ever wait to start it until the glowplug light goes out. I don't live in the coldest part of the country. But I still doubt it is all of your problem. Sadly.

Thanks. I’ve replaced all the plugs now, so I’ll torque them up and see how it goes.

Stanleysteamer · 2024-11-20T15:30:08+0000

Twinnie said:
Thanks. I’ve replaced all the plugs now, so I’ll torque them up and see how it goes.

Crossed fingers that that was your problem.

Twinnie · 2024-11-20T23:32:35+0000

Stanleysteamer said:
Crossed fingers that that was your problem.

Yeah, I'm not sure that's what it was. It started up better and it was colder today but I don't feel like it completely solved anything. It started first time after letting the plugs do their thing but it took a second or so on the starter to actually fire up and when it had started it was bouncing about all over the place like it was just firing on one cylinder or something. Also, there was a load of fumes coming out of the back. I only ran it a day or two ago so I wasn't expecting so much. It tailed off pretty quickly but then kept smoking for quite a while. I held a white rag over the exhaust because I thought it might have been burning oil at at first but it seemed fine and the oil level was okay. I also did the trick with loosening the oil filler cap but that seemed fine as well.

Once it had warmed up a bit it seemed fine. I'll trying start it tomorrow morning without waiting for the plugs and we'll see what happens.

1988smithy · 2024-11-20T23:53:08+0000

Hard starting can be an early sign of injector washers failing. If it develops to the point of cutting out and more general rough running it'd be worth a look. Keep an eye on your oil level as well, if you do the copper washers, change the o rings same time.

Bear in mind you have 4 glowplugs in a 5 cylinder engine. If the cylinder with no plug is cold it will chuff a bit of smoke and sound lumpy for a few seconds in very cold temps

Stanleysteamer · 2024-11-21T00:50:35+0000

Twinnie said:
Yeah, I'm not sure that's what it was. It started up better and it was colder today but I don't feel like it completely solved anything. It started first time after letting the plugs do their thing but it took a second or so on the starter to actually fire up and when it had started it was bouncing about all over the place like it was just firing on one cylinder or something. Also, there was a load of fumes coming out of the back. I only ran it a day or two ago so I wasn't expecting so much. It tailed off pretty quickly but then kept smoking for quite a while. I held a white rag over the exhaust because I thought it might have been burning oil at at first but it seemed fine and the oil level was okay. I also did the trick with loosening the oil filler cap but that seemed fine as well.

Once it had warmed up a bit it seemed fine. I'll trying start it tomorrow morning without waiting for the plugs and we'll see what happens.

What happens with the glow plugs is governed, of course, by the ECM. @sierrafery will be able to tell you more about this than I can and may be able to throw some light on the situation.
But yes injector sealing could possibly be part of this.

sierrafery · 2024-11-21T05:24:18+0000

Hi, once the glow plugs were ruled out you must make sure if they get power too or not cos the waarning light will work normally even if power dosnt reach theplugs so unplug the the one which is easyer to reach and check for voltage in the plug while the warnig light is on

if that's confirmed check the ECU red plug cos oil in it can cause various symptoms and if it's oily replace the injector loom ASAP... also another suspect for difficult starting is the air bleed valve in the rear wheel side port of the fuel filter head(WJN500110) .... there can be management issues too but these can't just be guessed, a compatible diagnostic tool is needed

Testing and changing the glow plugs on a TD5

Twinnie

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miktdish

Guns n Chainsaws

changing TD5 GLOW PLUGS?

Twinnie

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Stanleysteamer

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kermit_rr

Very

Twinnie

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Stanleysteamer

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Twinnie

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1988smithy

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Stanleysteamer

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sierrafery

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