So, my son helped me change the housing last weekend. OK, OK, he did most of the work and I helped him a little bit. But it was fun hanging out with him - I don't get to do that enough anymore - he's 24 now and a great mechanic. I just wish one of the other kids was a doctor. Oh, well.
Thanks for the write-ups, the tips on the tricky parts really helped.
However, we had trouble with a couple of things that I don't recall having read about.
We removed the alternator, and wanted to remove it's bracket to get at the lower hose and little easier. Unfortunately, there's a bolt behind the serpentine belt tensioner that would not come out - it loosened up a bit, but then got really tight again. So we tightened it back up and gave up on that.
The next problem was that the sensor on the left wouldn't come out; it would turn, but the threads were locked up, so that turning the sensor just turned it's fitting too. After figuring that out, my son got a chisel and broke the lower housing around the sensor to get the sensor out.
Having an 8 mm end wrench ratchet would have really helped to remove the bolt behind the sensors. One write up says that an 8 mm universal socket would get back there, but I don't know about that. There are about 5 different cables and hoses in the way. Removing the upper air intake would help, but then you need to replace that gasket, too.
After getting the housing out of the way, we found a giant mess behind it - there was a rather large puddle of coolant underneath the lower air intake. So we mopped up as much as we could.
Then it took us a while to find the right order to install the lower hose. We ended up figuring out that we needed to put the hose on the lower therm housing first, and then slide the hose onto the fitting at the water pump. And that's where it would have been nice to have the alternator bracket out of the way.
After that, finishing up was fairly routine.
Judging by the build-up of crusty coolant on the housing, my guess is that it was the lower gasket that was leaking the most. And/or it was leaking at the sensors. And what I mentioned earlier looked like a hole in the housing, was really just the shape of the housing and the arrangement of dried crystals of coolant.
One thing that I hadn't seen mentioned before... fill the block with coolant before you install the thermostat. Just be sure to tighten the valve at the bottom of the radiator and put the radiator hose back on if you removed it.
One more thing, I got the parts kit from O'Reilly Auto Parts made by Murray. The sensors were the screw in type, not the clip style. The first one lasted about 13 years and 220K miles or so. I hope this one will go a while too.
Cheers! and Thanks Again for all of the help!