How to Change the Thermostat in a 2003 Pontiac Vibeby Richard Rowe
Back in the day, I seem to recall hearing somebody say that American brands don't sell in America anymore. Maybe that's true, in the sense that Buick sells more cars in China than it does here. But I know I bought my Pontiac Vibe because of the Pontiac name. Sure, it's technically a Toyota Matrix underneath -- but I'll take a name that preceded "Firebird" before I will one associated with "Camry" any day.
The Vibe's engine bay is pretty cramped, and I could tell looking in that Toyota engineering was about to strike again. In order to get to the thermostat, I had to remove the alternator first. I started by draining the radiator with the drain petcock on the bottom. Then I set about removing the plastic cover on the top of the valve cover to get a little more clearance over the belt. I reached down toward the back of the engine, and used a 19 mm socket and ratchet -- pulling the handle toward the radiator -- to relieve pressure on the belt. With the tension released and the belt off, I checked it for cracks, splits and frays, and then turned my attention to the alternator.
I disconnected the alternator wire clamp, then removed the terminal cap and nut, and then the wire. From there, it was a matter of removing the two alternator mounting bolts, and pulling it out to access the thermostat housing behind it. The thermostat housing came off after removing its two bolts, and the thermostat came out afterward. After pulling the O-ring out, I tossed it in the trash. I cleaned the block and housing mating surfaces, and installed a new thermostat with the little bleed valve pointing straight up. With a new O-ring installed, I pushed the housing back on and installed the bolts. This was the high-output engine, so the bolts took 7 foot-pounds of torque; if it had been the standard engine, it would have been 8 foot-pounds.
The alternator went back on the way it came off, taking 18 foot-pounds of torque on the upper bolt, and 40 foot-pounds on the lower. The little wire nut took 86 inch-pounds, which is just hand-tight if you don't have an inch-pound wrench. I reinstalled the belt, pulling the tensioner forward again to slip the belt over the pulleys. After double-checking that it was seated on the pulleys, I refilled the system, bled it to get rid of the air, and checked my belt for alignment and thermostat housing for leaks while it was running. After everything was checked and done, I reinstalled the plastic engine cover, bought a giant firebird "Flaming Chicken" decal and stuck it to the hood.
Richard Rowe has been writing professionally since 2007, specializing in automotive topics. He has worked as a tractor-trailer driver and mechanic, a rigger at a fire engine factory and as a race-car driver and builder. Rowe studied engineering, philosophy and American literature at Central Florida Community College.