I read a lot of posts with various problems with the 3.2 and later motors, yet the 3.1 in my '92 Rodeo just keeps plugging along. I've chased a perpetual EGR issue, which never shows until we take a longer trip, but even then, it has never seemed to affect how it runs. Engine-wise, I've had to replace a few distributor caps and plug wires, a couple fan clutches, one Idle Air Control valve, thermostat and a few other minor things, and chased a few coolant and oil leaks, but it's never needed more than occasional topping off of fluids. Burns less than a quart of oil between changes. Only one O2 sensor, changed once. Pre-OBDII, so not much info for codes, but maybe also less to go wrong?
It has a timing chain, not a belt, still original at 140k. Throttle-body injection, pretty much conventional distributor and single spark coil, so no balky separate injectors or hi-tech ignition system to troubleshoot. Open the hood, you see the motor and an air cleaner like on my old '67 Ford Falcon, not all those glitzy add-on coverups and bulky intakes, hoses, wires and what-not. I get overwhelmed just looking at the pics of the newer engines!
It was pretty gutless since we've owned it, till I finally had to replace the old exhaust with a slightly upgraded one with free-flowing cat and muffler. It was like setting it free, it had a lot more power and snap ever since that one change from stock. It might be the lowest HP of the various sixes found in the Zu's, but it does the job for me.
The rest of the vehicle has been dependable as well, but it's getting worn out and rusty after 21 years of dirt, mud and snow. We've sunk far more money into keeping all that up than we ever put into the motor itself. Still, it's been very cheap to maintain, considering the years of use and abuse. Getting things diagnosed is another thing, nobody around here seems able to troubleshoot stuff and just wants to throw parts at it, so I do most all the wrenching myself, same as on my other rigs. That way, I know what's done and how well.
I just don't see much here on the ol' 3.1. What's other people's take?