UPDATED! 23C glow plug information
The 23C engine has four glow plugs, one for each of the four cylinders.
They are specified in the MF manual as
Up until recently I had three KLG and one Lucas/CAV plugs (the Lucas/CAV is the most recent). However, because the ballast resistor finally fell apart, I decided to switch from the wire type glow plug to the pencil (probe) style.
The ballast resistor unit used with the original wire type glow plugs was specified as KLG Z. 174/1 - 3.7V - 36/40A (up to S/N 156502) and after this serial number, KLG BRQ. 1 (3.7V - 38/42A).
The replacement pencil style glow plugs #GAM-101 are 12 volt, and require a solenoid instead of the resistor coil (see below). They are available from lrspareparts.com in England. They are quite inexpensive, and shipping by mail is quick and not expensive either.
To go with the original setup, a pilot lamp, Osram (England) bulb, 6V and 3W was used (See the diagram on my tractor page). Up to S/N 156502 a 12 volt bulb was used, but later a 6 volt one was used. Apparently the 6V bulb can be used with either 6 or 12 volt systems. This bulb may also be obsolete and unavailable now.
Here is a diagram of the original setup with the glow plugs in series and the pilot lamp fitted across the ballast resistor:
My coil broke a few years ago and I had it welded up. However, it recently broke againin the same place as beforeso I made a brass clamp which ties the two broken ends together. This worked for a little while, but it finally broke in several places and was found to be beyond repair.
Based on entries on a Land Rover forum, I discovered that wire tipped glow plugs from the Series 2.25 diesel engine would fit the Standard 23c engine, and further that most of the owners of these older engines had switched to pencil (or probe) style glow plugs. I contacted LR Spare Parts in England, and they compared measurements of my wire plugs with their pencil style plugs and confirmed that the latter would fit my engine. One of the new glow plugs is shown next to the old ones at the top of this page.
Since the new glow plugs run on 12 volts, they are connected in parallel rather than in series like the old ones, and to go with the new plugs, I inserted a solenoid (Unipoint SNLS-12B) between the starter/heater switch and the plugs so the switch wouldn't have to carry the heavy current draw by the plugs.
Having worked with this new setup for a while now, I can report that it works very well indeed. At an ambient temperature of 5, I heat the engine for about an hour (as explained elsewhere) and give the new plugs 10–20 seconds of heat. After this, the engine starts up right away.
A note about attaching wires to the glow plugs
Now, for the conclusion to this story:
He took away the dead resistor and returned a few days later with this beauty:
My friend used 14 gauge Nichrome wire, made new fibre washer insulators, drilled holes in the brass studs for the wire ends, silver soldered the wire to the brass studs, and even gave the steel enclosure a coat of primer. So now I have a brand new ballast resistor in case I ever should want to reinstall the old wire glow plugs.