For anyone reading this, go buy a scangauge! This has saved me a lot of heartache two times this month.
1. I was driving to the deer lease which is about 110 hilly miles away. My water temp is usually in the ballpark of 182-188, and I might touch 190 with some other factors at play. I noticed on my way down that my water temp hit 190, then 192, then 194, and finally settled out around 200-202 and I was able to control it and get back to 188-190 by keeping my speed down. Oddly enough it has not done it since, but to me this is a clear indidcation of a sticky thermostat. My analog temp gauge in the cluster read normal the whole way, glad the scangauge told me of an IMPENDING issue before it happened.
2. I have seen since I got this scangauge that if I let the truck idle my voltage slowly dropped but came back with engine rpm. Never caused electrical or starter issues ever, except one time last summer I was on the tractor planting a good plot and left the car idling with AC on. I came back to a flickering radio and gauges. I drove a quick lap and voltage was back. Well on Thursday my alternator completely died on me, but again scangauge made this an unbelievably quick diagnosis.
I was beyond lucky that Toyota of Dallas had the alternator on the shelf for ~$200 plus a $75 core, which I returned the same day. There’s a big thread on it and some people made it sound like a 2 banana job, IT IS NOT AN EASY JOB. I think the 98-99 models came with an 80 amp alt that is physically smaller that the later model 100 amp alternators. That’s makes the job significantly more difficult. The power steering pump needs to be unbolted and pushed out of the way (this isn’t inherently hard), and squeezing the alternator out and back in is a huge pain.
My serpentine belt was super cracked and dry when I pulled it to unbolt the alternator and PS pump. No problem, I had to drain the coolant to pull the lower rad hose and pull the alternator so I needed coolant at Toyota anyways. ALSO was a good time to do my thermostat which has not failed but I know is sticky.
Also did an oil change with my usual amsoil and Toyota filter and a fresh drain plug washer.
Got it all put back together and filled up and immediately showed adequate voltage 13.8-14.2, I had no more chirping or squeaking from the engine bay. (I inspected my pulleys and they all spun great and my tensioner had plenty of life left). My AC clutch would squeal some when it engaged and that is all gone. I have also been chasing a hum that comes with engine rpm and it must have been my alternator because it is long gone. Overall the truck is purring better than ever and I’m very happy with the outcome because that alternator job was a PITA!!