Boiling in the coolant reservoir

1996 CADILLAC SLS
120,000 MILES • 4.6L • V8 • RWD • AUTOMATIC
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DAWN BOWEN-SCHARP
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  • 1 POST
It boils out the over flow in the reservoir only when the heat or AC is turned on. Replaced water pump, thermostat and reservoir. What else could be the problem? No problems with engine power or anything else.
Aug 9, 2017 at 7:50 PM
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HARRY P
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  • 2,292 POSTS
It is possible that the radiator is clogged. You could flush it and see if that helps. It is also possible that the fans are not running, which could be caused by a bad coolant temperature sensor.

To start, I would check that the fans come on. Start the car, turn the A/C on full blast, and drive it around the block. When the engine is fully warmed up, raise the hood and watch the fans while the engine idles.

Start with that and let us know. We will go from there.
Aug 10, 2017 at 4:19 AM