It has been a little over a year and much progress has been made.
The timing problem turned out to be the ignition module located in front of the battery on the radiator support. AutoZone's replacement module ($172) provide impressive results. It was like unhitching a heavy trailer. I drove in default mode for more than a decade, while scratching my head. Apparently, OBD 1 is reluctant to light the CEL. This was also a boon to the A4LD; it no longer hunts for gears at every speed and incline.
There was a high RPM misfire under load, 4,000 RPM, 3rd gear on a 6% incline. The coil pack was replaced and the misfire abated.
A stalling condition cropped up. A bad ground spice where the small wires join the negative battery cable. Repairing the harness cured the trouble.
The under hood temperatures were hot and the fluid would boil in the recovery bottle. The radiator was replaced (2 core radiator was $121 at autoZone). The inlet tank was removed from the old radiator to find the aluminum in excellent condition but many of the tubes were blocked with silicone sealer strips squished out during previous water pump replacements.
The bushing in the water pump wore out allowing the fan to hit the shroud. The fan flopped around quite a bit considering the seal didn't leak. The belt starting to come apart was the symptom. The pump was removed and replaced (O'reiely's honored the Trak Auto's lifetime warranty) with the fan blade. The shroud has some score marks which were broken off to allow the bottom of the shroud to be about 1/2 inch lower. The belt, tensioner, idler bearing, radiator and heater hoses were replaced with the thermostat.
This was the perfect time to get back into the timing chain. The sprockets were perfectly set and in time. The slack adjuster was protruding near its limit and the guide was grooved from the back side of the chain. The timing set was replaced yielding an increase in power. The sleeve (Felpro) to fix the groove in the power pulley was too short to reach the seal area and went unused. Grease was used to hold the paper gaskets during assembly (no more silicone to plug up the radiator). There are no leaks.
It quit starting when hot; the fuel pump relay was replaced to fix it.
The air conditioner evaporator was replaced and now it stays cold for more than a month.
The rear brakes were inspected resulting in new axle bearings, seals, one axle shaft, new differential oil and friction modifier, wheel cylinders, shoes and 1 drum. Now the rear brakes do something, but they did not drag.
Around town mileage is still 12.5 to 14 miles per gallon. Close to 16 if there are a lot of freeway miles. There has yet to be a road trip.
I love my first generation Explorer. Maybe I'll paint it, replace the drooping headliner and pitted windshield. I could have another decade in it.
