1998 Mercury Sable

1998 MERCURY SABLE
143,000 MILES • 6 CYL • FWD • AUTOMATIC
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DORISANDROCK
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  • 1 POST
Where is the thermostat? This is the strangest cooling system I've ever encountered.

Does the coolant reservoir cap also serve as the "radiator" cap?

I think we have a leak in the reservoir cap, which makes it run low in antifreeze, which, in turn, makes it run hot.

While running, the temp gauge goes up to hot for 2 - 3 seconds then back down to normal repeatedly. There is no warm air going to interior heating system.

Sometimes, not always, filling up the reservoir makes the interior heat work.
Nov 25, 2008 at 8:52 AM
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ZACKMAN
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  • 4,202 POSTS
Your coolant cap is pressurized, acting as your radiator cap. If it is leaking, you are loosing pressure which make your car runs hot, but no heat in the cabin. Adding coolant into the system will give you cabin heat for a short while until all coolant is evaporated through the cap.

I don't think it is your thermostat, although it is nice to replace if it has been done for a while, but do replace your coolant cap.
Nov 26, 2008 at 1:05 AM