Unusual glowplug failure

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Unusual glowplug failure

Post by spider »

Had this a couple of days ago but I wanted investigate it closely.

Symptoms: No start. Fuel being supplied. A closer examination revealed no supply to the glowplugs even though the warning light operated.

Powering it up I could feel the contact move, confirmed there was power present in the heavy input feed (I think its partly wired to the internals anyway as well as the usual four connections on the plug) , temporarily shorted across heavy input / output terminals with a large bar (ahem :oops: ) for a few seconds and then we started quite well. I did consider the welding effect but its not that much current compared to a starter which is a bit dubious doing this "practise" with.

I was unable to obtain a new matching one at sensible cost and did not want a used one as it may have other issues, plus mine did not really seem to supply the plugs long enough anyway (new plugs)

A late ZX / 306 on fitted, I'd already checked the wiring diagram in advance to compare them for any potential concerns but no, its wired the same:

Ignition feed
Starter feed (to switch it off when cranking)
Warning light feed

It seems fine with its replacement, to be honest its actually better as even when warm (I will check the time with a cold start although it was a warm start it did not energise them for long enough, more so the light did not stay on enough rather than the supply) as it stayed on for a few seconds when warm, similar to my 205TD which was 6 to 8 seconds regardless of engine / air temp.

Upon examining the old relay, I had to cut it open due to its odd construction. The output pin itself, its not got a brass / copper braided strap on it, it appears to just have a metal plate in contact with it, nothing more ( ! ) , I can only assume it was somehow over tightened in the past or perhaps vibrated away from the contact pin itself, It would of been repairable in a fashion although I'd of had to glue the case back together, needless to say its in the waste now.

Anyway long and short of it, if its a 5 pin plug and only four wires are used, it won't have an external temp feed, it may have an internal sensor and one from another model will probably be quite suitable.

All sorted for £40 for new parts and about 30 mins to investigate, 5 mins to fit and half an hour to disassemble the original one for curiosity reasons. :-D