Re: 98 UP Explorer - 4L V6 - which engine?
The SOHC has a timing chain for sure, not sure about the lesser powered OHV engine.
The way to tell which engine you have is that the OHV will have the cam in the center of the engine, and the SOHC will have two cams, one per cylinder bank. I can't tell off hand with all the wiring and hoses on top of the engine as I've never owned one myself. I'm sure someone else will chime in that knows more about this particular engine, but you can also check out cardomain.com or autos.msn.com
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!