Thanks for the offer. I checked the points and they are really good. I suspect they had been changed not long before I got it. I used the GB75 cap, leads and the plugs from the other truck as they were brand new.
Well, some progress.
Today I reconnected some wiring under the dash and fitted a huge battery I rescued from a burnt out 30t excavator at work. It is a sealed type and almost new. I had it on charge/test on my charger all week and it tested as good as a new one on the carbon pile tester. Way bigger than the piddly little car one that was in the truck before.
I pumped some fuel through from the boat tank, until it showed in the glass float bowl, held the choke lever down with a finger and hit the starter. It fired and ran in under 2 seconds, way faster than it used to. I suspect the really worn plugs and corroded lead connections were causing problems.
While cold, I could hear that it needs the tappets adjusted. One in particular was very noisy. Another job to add to the list, but one I was expecting. The oil pressure gauge showed good pressure, but the fuel gauge was off the scale. I suspect that the wire has a rub-through somewhere underneath. When I switch it to the rear tank it dropped to empty, which is what the front should do.
I only needed to hold the choke on for about 15 seconds before it was idling happily. The Temp gauge didn't move off the Cold peg, but I had suspected it was dodgy as they have fitted an aftermarket temp gauge to the front panel next to the air cleaner monitor and the sender unit to a bolt on the head. It worked. I never thought to check while I was out there, but if I had of pulled the yellow wire off the original sender unit and shorted it to earth, I would have been able to check if it was a faulty sender or the wiring to the gauge on the dash. Next time.
The Amp meter happily trembled away. It didn't really change much, even when the revs were up high, but the battery was straight off the charger, so it probably wouldn't have wanted any amps off an old 1970's alternator. I know the MK3, with the generator, showed 20 to 30 amps when the engine was revved, but that was with a different battery that hadn't just been charged, and had used a fair bit of power getting the truck to start.
The tacho moved smoothly and the air pressure gauge moved up to 200kPa and sat there, which was odd. If I increased the revs, the pressure slowly crept up, but dropped back down to 200 if I took my foot off.
I moved around a bit and realised I could hear hissing. The little air valve on the hi/low range transfer case lever was leaking badly. Air was blowing up from under the lever. I recall pulling it apart and putting new o'rings in it, but maybe I put it back together wrong. If I lifted the lever, the leak stopped, so I grabbed some electrical tape and locked it back.
I could still hear hissing. This time it was the winch engage/disengage valve behind the seat. I shut everything down and pulled the valve out. I remember when I put it back together that I couldn't remember which way around the red plastic disk went, but that I had a 50/50 chance on getting it right. Guess I picked wrong.
There were 2 types of valves used for the winch engage/disengage system. The early type was a piston type and the newer type, which I have, is a rotary type. The air comes in the bottom and, depending on whether the handle is up or down, sends the air out to either the line that shoots the winch engagement piston out or the line that makes the piston suck in. The red plastic disk inside has a series of holes and slots that direct the air around. There is an outlet on the top of the valve that has a bung with a hole in it to let the air out of the winch engagement piston when you flip the lever. Mine was dumping high pressure air out here. I pulled the valve apart and rotated the plastic disk 180° and put it back together. It's pretty worn, and after refitting it I found it still leaks a bit, but it's way better than it was. I'll have to search around and see if there are any rebuild kits available. At the worst, I will have to swap it out for the piston type one from the MK3, as it uses o'rings and is easier to rebuild. Both types were PBR units. The rotary type was a PA625. The rebuild kit was CA62-14. The NSN is 2590-66-011-3037.
Even with these 2 leaks mostly sorted, the pressure gauge wasn't going up. Plan B.
I ran the hose out from my compressor and hooked it up to the truck's air system. I previously fitted an air tool nipple to the diff wading inflator valve under the dash. I just plugged the air hose onto this, opened the valve and pressurised the truck system to 60psi. With the truck turned off and the compressor way down in the old outside dunny, I could clearly hear a hissing under the truck. It sounded like it was coming from the back of the transfer case or maybe the winch air actuator.
Once I got under there, I found both of those were fine. It turned out to be coming from one of the steel lines that run to the tractor protection valve down the back. I felt around and found both pipes were leaking. This was an area where there was a lot of dirt sitting in the chassis rail. I can't get at it from underneath to clean it properly, so will wait until I lift the deck off. With that off I can pressure wash the whole length of the chassis rail and get at the pipes a lot easier. It looks as though either the bolt or clip that secure these pipes up to the wall of the rail has broken, letting them drop down into the dirt and rubbish and rub on the bottom of the chassis rail. Luckily, I still have 3 lengths of new steel pipe that I can use to replace the rusted air lines.
It was good to have it running again, and I am that little bit closer to having it driveable again.
Greg.
