I spend the last 2 days changing a thermostat in a Pontiac Montana with the GM 3.4 engine. The engineer who designed this needs a good flogging.
Normally a thermostat will take, what, 30 min to 1 hr? This one took me 2 hrs to get out and 5 hrs to put back in. There's a crossover exhaust pipe that goes over the rear housing bolt. There's no possible way to get a hand on that bolt without pulling off the entire exhaust system.
It was a nightmare putting it back in. 1st, I got a 12" pair of needle nose pliers. I'd carefully hold the bolt over the hole then try to push it in with a long screwdriver. Normally, the bolt will fall out and has to be located blindly off the transmission underneath. If you can get it lined up without being able to see it, you hold it with the screwdriver and use the needle nose to try to turn it 1/20th turn at a time until the threads catch. Usually it will fall out first. When, after a few hundred tries, it does catch, you need a weird wrench to turn it. I took a 6" 13mm wrench, cut the box wrench off the other end, bent a 75 degree bend in the handle, and ground down the sides of the open end wrench to get it between the bolt and the stat housing. I had to heat and bend the open end a number of times before I could get it to work. I got the bolt in about 1/2 way with that. Then you need a 6" straight 13mm to finish it. You hold a light in your mouth while you lie on top of the engine. You reach under the exhaust crossover and fingertip it. It's 1/12th of a turn at a time, turning the wrench over after each turn. If you're strongly left handed, you have a big problem. Luckily I can do some things with either hand.
In the meantime, you wrack your brain to come up with polite synonyms for 'shucks', and 'fooey'.
They tried to be smart by making the rear hole in the stat housing a slot instead of a hold so you could loosen the bolt and leave it in. That would be fine if the stat was flush with the block so you could slide it in but it isn't. It sticks out a 1/2". So, the housing has to be angled in but it can't be angled because of the exhaust pipe.
I probably saved $200 in labor but spent $400 in frustration.
