1999 Mercury Sable over heating cooling problems

[Anekretia]

the fans turn on via temp, not time.

[requeth]

My sisters car is doing the same thing, heat wave hit up here in N Minnesota.

[wildbaseballplaya]

I think the aftermarket

cap is now my last culprit. Will post in a few weeks after testing

new parts.

[wildbaseballplaya]

I did have a little overflow from reservoir, which upset me. I thought my troubles were over. I found out that the reservoir. cap had a 2

stage tightening sequence to it. So I tightened all the way, and problems

so far. Had to remove cap often to check antifreeze level, because I

cannot see through reservoir. The plastic has darkened. So. a new reservoir, cap, and lower radiator hose is upcoming.

[wildbaseballplaya]

update: The car is back in town. I changed to a Motorcraft Thermostat. And Walla ! The fans now stay on for about 2:30 minutes and go off for about 1:20. It actually did what I wanted the fans to do, switch

cycles. But I did not know the thermo would do that. I assume it is

staying open longer and telling the ECT to keep fans on longer.

NO MORE aftermarket parts for me, on most things. Especially if

it is cooling related.

[wildbaseballplaya]

Well, I found out how to keep fans on longer when the a/c is not on. Unplug the ect sensor. I believe this is going to fix the overheating

problem once and for all. I already know 2 small downsides, engine light

comes on, and it will take longer to heat up coolant for optimal efficiency

and for heater. A fair trade off, to be able to drive it without worrying

about it overheating AGAIN !