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[JimT]

I have a 1999 2.5TD estate that will not start. Fuel seems fine at the output of the fuel filter. I have disconnected the glow plugs relay and measured the resistance to earth of each glow plug lead. It measures open circuit, suggesting that all six glow plugs are blown. That seems hard to believe. The voltage at the output of the relay measures 12V before switching on the ignition. I would have expected that to be OV. Makes me think the relay has blown and that's taken all six glow plugs with it.

Tracing the wiring from the relay to the glow plugs it seems to disappear into a king of plastic covered distribution box on the engine crank case and the glow plug leads come out from there. That's very hard to reach under the inlet manifold and I can't check if there is anything wrong in there.

Any ideas will be appreciated. Thanks, Jim

[Dave DND]

Not uncommon for some of the glowplugs to burn out with age and go un-noticed, and only when the final one goes that the engine has been relying on to start, do you suddenly realise that all are faulty.

Easy way of testing them is to hold the body with a battery jump lead that has been earthed to the body, and then briefly apply 12v to the terminal -

It should get roastingly hot, very quickly - watch your skin !!

If not, its knackered.

 

[zirk]

I have a 1999 2.5TD estate that will not start. Fuel seems fine at the output of the fuel filter. I have disconnected the glow plugs relay and measured the resistance to earth of each glow plug lead. It measures open circuit, suggesting that all six glow plugs are blown. That seems hard to believe. The voltage at the output of the relay measures 12V before switching on the ignition. I would have expected that to be OV. Makes me think the relay has blown and that's taken all six glow plugs with it.

Tracing the wiring from the relay to the glow plugs it seems to disappear into a king of plastic covered distribution box on the engine crank case and the glow plug leads come out from there. That's very hard to reach under the inlet manifold and I can't check if there is anything wrong in there.

Any ideas will be appreciated. Thanks, Jim

The input of the relay is wired directly (unswitched) to the battery, when ign. is switched on and the GP light comes on the dash the 12v gets fed to each plug and stays on for about 5 seconds after the dash GP light goes out so should be plenty of time to measure the 12v if your quick. if you pull the connector of the top of the relay you should be able to measure each glow plug in turn (the six slightly thicker black wires) should be around 1 or 2 ohms each depends on the meter.

Also check the big brass fuse held on with two screws, its not uncommon for the relay contacts, 2 of them, to arc across and start to supply 12v on its own, your need to take the relay apart to check, meaning the GPs are being fed when not required, this could be the problem and may have shoot the GPs, but to be honest I would not have expected all 6 to go, and would have thought you would have had some low battery issues, they can flatten a good battery in about 15 mins.

Chris.

[JimT]

Many thanks for your comments. Having checked again it looks like the relay has blown and also the glow plugs. The resistance measurement from the output of the relay is very high (several megohms) to each glow plug lead. That was an interesting point that perhaps some of them may have been blown for a long time but had no effect on starting.

What's the best way to get access to the glow plugs? Is it necessary remove the inlet manifold?

Thanks.

[robg1984]

Yes you have to remove the inlet manifold, i did my glows a couple of weeks ago make sure you get alll the bolts off the inlet manifold as i found that the person thatd done mine before me hadnt and managed to crack part of the manifold near the bolt and bodged it back together with exhaust putty! make sure you get the inlet manifold gaskets as well as you can gurantee that if you dont youll need them, they was about 3 quid each when i bought them 
hth
rob