You don't have to remove the t-stat housing if the t-stat is working properly and the seal is not leaking. In the link below, you can see where he is talking about the removal of the metal pipe and bypass hose. He does mention that the pipe may have to be removed from the other end to get enough leverage for removal. BTW, be sure to replace the bypass hose, along with the plastic fitting with the newer metal replacement. The metal hose fitting, can be found at most national part stores in several brands, like Dorman, Help, or Motormite and comes with 5/8" hose x 1"-14 thread. All three of these aftermarket fittings use the same Part #56359 and are available for less than 5 bucks. Of course, if you prefer, most GM dealers would have a replacement metal fitting, Part #25535749 for 15-18 bucks. Keep in mind; this fitting is only for the
VIN-L 3800 engine and not for the 96 up
VIN-K 3800 Series II. The
VIN-L engine came installed in Buick,
Olds and
Pontiac, in various body platforms.
For removal of the fitting, (if you don’t have a large thread extractor), you can use a flat chisel about the same size as the I.D. of the hose nipple. The cutting end of the chisel is tapered and should go up into the threaded piece about 1/2 in. You will need to bump it in with a hammer far enough, to get a grip on the fitting. Once the chisel is snug, use a crescent wrench to turn the chisel “counterclockwise” and that will loosen the fitting. (It should start coming out). If the chisel slips on the first try, tap it in a little further, then try again.
https://www.youtube.com/watch?feature=player_detailpage&v=kHttEVGiOgs#t=222
