Having problems with your 1999 Pontiac Grand Prix ?
When you replace thermostat where does the gasket (o-ring)go? Does it go under thermostat(motor side) top of thermostat (hose side)or does it go on the flange of thermostat gasketing both sides top and bottom ? 1999 grand prix 3.8 v6
It should be a rubber ring that actualy stretches& goes around outside edge of thermostat.
Repair Help & Product Troubleshooting for 1999 Pontiac Grand Prix
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