Club 80-90 Forums

It is remotely possible that a glow plug has melted so that it touches the head internally causing the short but I would have expected it to have been the busbar touching the head or coolant flange as more likely. Is the plastic in place along the length of the busbar with no chance of it making contact anywhere?

That seems logical to me.
In the photo you can see what is happening to the bus bar, the insulation is peeling away. But for the areas not visible I traced my finger along the bar and could not detect any contact with surrounding metal.

It'll probably be a short in one of the glow plugs then.

Just to round this off, with special thanks to all who gave input, it apparently was the bus bar. Once it was off the plugs tested OK individually. The two easily accessible ones were replaced while my mechanic (who had removed the fuel lines) balked at the extra uncertainty/difficulty of taking out & replacing the others. He did not like the look of the lack of headroom for getting them in and out.

The bus bar was a mess, but still I can't figure out where it was shorting!

Glad you got is sorted.