Replacing Glow Plugs

[Lucio]

Ok, apparently at least 2 of the glow plugs on my N reg Seat Ibizia 1.9tdi are dead and not getting any electricity.

Whilst I can get the car started using some Cold Start spray, I really want to get this fixed if possible but I'm *really* short of money.

Is this something you can fix safely yourself, like you would a spark plug on a petrol car, or is it more complicated? I've taken a quick look, and it seems that the biggest problem is getting the two by the fuel pump free without hitting it but I know that often cars seem straight forward on the surface and then get really complicated!

[jimbouk]

Haynes manual might be a good start for this, you can pick them up second hand on flebay cheap. Should walk you through it step by step.

I can't imagine it'd be an impossible job though, I'd probably start by unplugging the battery just to be on the safe side.

[kalniel]

Very similar to a spark plug on a petrol car. Biggest problem is if they stick, you force them, and they break. Expect that's the same with a spark plug too!

[jimbouk]

Just a thought, when you say they hit the fuel pump is this just the rigid bar on the wrench? If so then a universal joint at the end might sort it out.

[Rave]

I did the four on my mum's Clio when it finally refused to start at all (the weak battery didn't help, but it lasted one more winter after I did the plugs).

Two of them were easy enough, but two were an absolute bastard just because of the fact that I couldn't get a wrench on them and I only had about 15 degrees to swing a spanner. The whole job took me a couple of hours just for that reason. If I was doing it again I would definitely either buy or borrow some ratchet spanners. Lidl were/ probably still are doing a set for £20, well worth a look if access is tight if you ask me, I'm sure it would have saved me a lot of time.

[megah0]

If you do snap them, depending on model, its generally a head off job to get the stuck plugs out, go carefully with lots of penetrating oil.

[mountainmachine]

Glow plugs aren't like spark plugs, only used before the car starts, replacing even 2 will make a big difference. If you can do the job yourself then get a haynes manual some tools and give it a go.

[Lucio]

Right, glow plugs replaced, problem still persists in that it turns over, but doesn't start, or come close to starting. The one thing I didn't try is i have a mystery switch on my dashboard. It's a light up rocker switch, that when the headlights are on and it's switched one way, illuminates. This appears to do nothing as far as I can tell in the car, could it be a pre-heater switch?

[GoNz0]

rear foglight ?

can you test the other glow plugs with a multimeter ? maybe a partially blocked injector as well m8.

[Lucio]

rear foglight ?

can you test the other glow plugs with a multimeter ? maybe a partially blocked injector as well m8.

Unfortunately I don't have a multimeter. I'm tempted to call the RAC out again and go "I just fixed the problem last week but it's happened again"

I think replacing the glow plugs was still needed, as the engine noise has definately changed once it did start, and it started straight away instead of needing to be tried a couple of times, plus it's no longer shaking as much.

[GoNz0]

what happens if you cycle the preheat 3 or 4 times b4 starting, ie key to 2 until the glow plug light turns off then do it twice more b4 firing up ?

i used to have to do that in a old van until all the glow plugs got swapped.

[peterb]

The preheat is automatic - the switch on the dashboard is (as Gonz0) says) more likely to be a fog light (front or rear) switch.

You say the engine noise has changed, but it still isn;'t starting. In what way has it changed? Are the replacement glow plugs properly seated? If you aren't getting compression, the engine won't start.

The other problem may be the pre-heater timer. This is normally a relay that activates the glow plugs for a pre-set time - and also activates a glow plug light on the dashboard (depending on the age of the car.)

The only reliable way to tell if the glow plugs are getting power is with a meter (or you could use a low wattage (eg a tail lamp) bulb as a test indicator, connected between the glow plug power connector (on the top) and the chassis.

[alpha channel]

I've owned a couple of diesels (an '86 Pug 205, great car, and a Clio, crap car, good miles per gallon though). You've sorted the plugs, I'd look at power (the battery can get discharged fairly rapidly when turning over time after time) and give the air filter a quick whack and clear it out. Diesels have a holy trinity - electricity, air and heat if it's not getting one it'll not start (that's my experience anyway, had a lot of fun after replacing the engine in the Pug trying to get the thing going).

[Lucio]

Well, I've found the relay, going to test what happens when its unplugged and might have a multimeter to use as well

[Lucio]

Right, got to the bottom of this at last

In addition to the relay and the glow plugs themselves, there's also a 50 amp fuse hidden on top of the fuse box. Basically under the steering wheel there's a small catch, pop that, and then press the two restraints in to remove the panel. You'll see the fuse box with all the 5-30amp fuses in a row, plus several relays, which tend to be plastic boxes with numbers on.

At the very top of this, there's a 50 amp blade fuse about 3cm long, mounted horizontally. This controls the power to the glow plugs and once I'd replaced this, it sovled the problem.

Right now I'm trying to not wonder whether I should have replaced this first, but never mind, car's working again

[GoNz0]

something made it blow and you have swapped that so nice one !