A month or so on and progress has occurred. The new water pump is fitted and through some miracle the system bled up fine.
After that I wanted to check the condition of the winch ropes to determine if I should re-splice the rear rope* or buy new, this of course would mean spooling out some rope to check the condition. The last time I ran either winch was last June when I traced the fault on the rear to a loose connection on the isolator (I didn't post this) and neither have been used in anger since I bought the truck 3 years ago.
Neither winch worked with any control. Odd. Checking the aux. battery voltage gave me 2V, clearly not enough to run the winches or anything else. The truck has a split charge system that uses a voltage sensitive relay to link the batteries together only when the voltage exceeds 13.3V, however checking the fuse holder that is linked with this relay revealed that there was a large air gap between it and the main battery +ve terminal. Testing the fuse revealed it was dead and tracing the cable from the relay to the second battery revealed another air gap between it and the aux. battery +ve terminal. I never checked any of this stuff when I got the truck, NAUGHTY SLAP WRISTS.
This has taken some time to sink in, as I didn't remove any cables this means that in the entire time I have owned this truck and have used either winch unloaded, there has been no real charging for the aux. battery. Only a small link cable remained and this was only enough to get the voltage to 4V during testing. My conclusion is that either:
- The aux. battery capacity was staggeringly good and kept going with only trickle top up from the main, or...
- It was just very good and this tiny cable was able to sustain it, while the battery has degraded and is now close to useless through not being charged. After all, if it is still permanently connected by any cable you would expect the voltages to balance out.
Jumper cables stood in for the link between the fuse holder and main battery and showed that the 200A fuse was toast, probably due to the load from winching. Bypassing this and going straight to the voltage sensitive relay, after reconnecting the loose cable on the aux. battery side, got the whole thing working and the aux. battery showed 14V with both winches working. I measured current draw with my clamp meter and it hit 80A while running the winch with no load, no doubt because the battery is still depleted. Whether or not it will actually take a charge or if I'm in the market for an Optima yellow top is yet to be seen, some new mega fuses are on order (150A instead of 200A as the relay is only rated to 140A and I don't fancy melting it) and I think the link cable is in one of the boxes I got with it.
Never a dull day in Land Rover... land.
*After an idiot at an off road site hooked his tow tope to it instead of the tow eyes and it snapped - that's what you get for being helpful.