Successful repair
Over the weekend I successfully replaced the lower thermostat housing. Here are my notes.
First:
A. Fantastic writeups and part numbers made this possible. Wow. Thanks.
B. What a PITA.
C. This job flirted with the limits of my mechanical ability - I was in the deep end of the pool without a lifeguard! But maybe my limits are now expanded. And like felling trees, surviving it is a rush.
Everything basically went as described in the write ups with the following exceptions:
1. I had the same problem with the outboard temp sensor as described by this post:
Temperature sending unit will not unscrew.
The problem turned out to be the plastic tabs holding the internal brass nut (inside the housing) failed so the sensor just spun in place. The solution was more disassembly to allow removing the housing with the sensor still attached.
2. The interference from the routing of the camshaft position sensor cable directly over the top of the thermostat housing was a pain. In the end I removed the radiator fan and shroud plus the passenger front wheel to get access, then removed the idler pully so I could see that the cable was secured by two nylon press rivets. If I'd known that going in I could have just disconnected the camshaft position sensor then tugged hard on the wire at the nylon rivets to get it loose.
3. I have a vague recollection of seeing a mention of the heater hose problem. But I can't find it now so here it is again: The new lower thermostat housing's heater hose connector doesn't end up in exactly the same position as the original after reinstall. Fortunately the heater hose connection at the other end has an unusually long nipple, so just loosening the hose sliding it slightly inboard allowed everything to reconnect without leaks. If I had it to do over I'd replace this hose at the same time and cut the new hose slightly longer.
4. Definitely replace the bypass hose while you're there - you really don't want to do this again anytime soon.
5. Try not to drop sockets. It took me about 40 minutes to find the socket that fell off while reinstalling the throttle body. Sigh.
So with interruptions and the rental of the fan clutch tool the whole job took me about 7 hours. But then I'm old and feeble and my eyesight, manual dexterity and mental acuity are going to hell so it'll take you alot less time.
Bottom line: it worked perfectly, my leak is gone and I saved a pile of dough. Thanks again for all the great writeups.