I have a 01 Mondeo TDDI and i think one or more glow plugs are not working properly. On starting from cold the engine seems lumpy for 5-10 secs and there seems more smoke than usual. On starting from warm there is no problem. At all other times the engine runs fine. How do I determine which plug(s) may be faulty?
Once determined is it easy to replace them and do I need any special tools and are there any special precautions or tips anyone can offer? Thanks in anticipation.
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The most reliable way to test a glowplug is to activate it out of the car and see how quickly/evenly it heats up (if at all)
You will need a pair of long handled pliers (I used water pump pliers) and two lengths of wire stripped to about 10mm each end.
Remove the glowplug.
Hold the hex part of the plug with the pliers, and keep the tapered (heated) end pointing away from you.
Clamp the end of one of the lengths of wire between the pliers and the plug hex.
Connect the other end of this wire to the battery negative terminal.
Connect one end of the other wire to the positive terminal, (making sure the other end doesn't short/earth obviously!)
Touch the other end of the wire onto the threaded terminal on the end of the plug.
The tip of the plug should go orange within a couple of seconds and white a second or two afterwards. Make sure its uniform colour and that it heats up quickly.
If it does, the plug is OK. Put it down carefully on a non-combustible surface and leave it for at least 10 minutes before you touch it. They stop glowing as soon as you disconnect the power, but they stay hot enough to burn for a fair while.
If it doesn't the plug is knackered. Put it down carefully on a non-combustible surface and then bin it when cool.
Tools are just a deep socket of the right size for the plug itself, and a 6-8mm spanner for the terminal nut.
Cheers
DP
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I didn't think these TDCis used the glowplugs except in winter.
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May not be the glow plugs, it may be a dribbling injector, more smoke might mean excess fuel in the cylinders. Left long enough to cool down even a slight leak on an injector could deposit enough fuel to flood a cylinder. Safer way to check glow plugs is to measure their resistance. Even if you don't know what the resistance should be, they should all be around the same and a faulty one will usually be either open cicuit, i.e. off the scale (high) resistance, or short cicuit i.e. no resistance. Disconnect the wiring to each injector and check resistance between hex and connector thread.
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Thanks all for the advice. Hadn't thought of the injectors. The smoke is certainly bluey in colour. Would that give the lumpy idle for a few seconds after start up? How do I check the resistance of the glow plugs, as in what instruments to use and on what setting? Thanks
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Using a multimeter, set on ohms (greek symbol omega) or resistance, the resistance on a good glowplug should be less than 1 ohm. You could use a 12v test lamp, disconnect the glowplug, put your test lamp lead on the positive battery terminal and touch the glowplug connection point (small threads), the lamp should light. If it does not light or is very dim then suspect duff glowplug. BTW usually when one glowplug fails, the others follow shortly after, so IMO if you do find a duff one, replace all 4.
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