Missing 2 volts?

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New Member
Jan 22, 2017
Southport, Lancs
W302 C320 cdi
Hi, I've looked at the forum and searched but struggled to find a answer, but I've been puting this off for months now and as cooler nights aren't far away I need answers. My c320 cdi is slow starting, to much cranking, I fitted a set of Bosch heater plugs then a new (Beru) relay, then a second relay, all with no improvement. I've done a little research which revealed the heater plugs require 4.5 volts, when I check the supply at the plug cap it's exactly 2 volts, the large supply cable to the relay is 12.5v so I'm looking for answers, can anyone help or am I barking up the wrong tree? When I plugged one of the old plugs in just before it timed off it was just starting to glow red but nowhere near bright red or white.

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