Idk why y'all hating on 4.3L so much... My 1990 4.3L TBI (ancient) seems to be plenty for moving around, at least for me.
Tank before last returned me 18.9MPG in mixed conditions with city, highway, and mountains. Most recent tank returned 17.53MPG with nearly all of it being in-town driving. Pretty respectable for a 32 year old truck with a 3-speed automatic (TH400). Especially considering the fact that my dad's much more modern 2010 Tacoma (2.7L/auto/2wd) could only occasionally touch 17mpg in town. Most of the time it was 15-16MPG city and 23-24MPG highway. When hypermiling I did manage to squeeze 28MPG on Highway a couple times, but that requires looots of patience...
In comparison this 1990 V6 4.3L TBI with TH400 only feels 10-15% slower than my old 1995 V8 5.7L TBI with 4L60, but is 30-35% more fuel efficient. The 5.7L stayed at 12MPG regardless of usage or driving conditions. In winter hit 10-11MPG occasionally.
Adorned with a "W" code high-output 4.3L, I drove my 1993 AWD Olds Bravada for 24 years and 250,000 miles before selling it to a local teenager. The drivetrain was all a-ok when sold. It was the electric windows and door locks that were failing, a broken door handle, etc. Little things that a harsh Alaska climate and time will do. It was a fantastic, long-lived drive-train with a great reputation. Of course, I maintained it all those years. It's the reason that it survived; I got my money's worth out of it.
My Bravada got the same mileage as yours, if I kept my foot out of it.
Miss it dearly. It was a faithful Alaskan Sno-Go that never once failed to start in the cold and get me where I was going, even in the deepest snows and blizzards. Ever.
Come to think of it, I changed the oil every 3K to 4K miles, usually with Valvoline Durablend 5W-30. Used Mobil-1 grease, Auto-Trak II in the t-case and Mobil-1 75W-90 in the diffs. It went through numerous consumables ... forget how many sets of tires, shocks and struts, at least three sets of throttle-body injector assemblies, and two or three sets of O2 sensors. For many years, the MTBE fuel mandated up here, during winters, would destroy those injectors over time.
It had been up and down the Alaska-Canada Highway at least 3 or 4 times itself ... maybe more. I'd burn the O2 sensors out running that vehicle hard for 12 to 24 hour stretches along that lonely highway -- practically 5,000 miles up or down that Al-Can Highway between the upper Midwest and Anchorage. Miss it dearly -- it was a very comfortable workhorse with lovely captain's chairs. It was a terribly fancy S-10 Blazer in disguise.
. They're simple and typically pretty durable. If you've got this on an engine stand (not sure?) I'd definitely pull the pan and do a quick inspection. There's another set of bushings for the balance shaft which is above the cam. Also I'd change the rear main seal as that's a high mile leak point.
