engine over heats unless the heat is on all the way or when its idling. on 1999 Ford Escort

"1999 FORD ZX2 KEEPS OVERHEATING OR REAL CLOSE + TEMP GAUGE GOES BACK DOWN WITH HEAT WIDE OPEN AND FULL BLAST" guage starts moving up after 65 mph or 3000 rpms, like pulling a small hill. It will sit and idle all day in neutral and not get hot. no leaks, top radiator hose seems to be circulating. Fan seems to work well, keeps hose from ever fealng hot.

by in Mountainburg, AR on February 13, 2012
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1 answer 2 comments
ANSWER by , February 13, 2012
Sounds like your thermostat is failing and needs replaced. It isn't opening up to a full flow or hot position. Turning the heater on max. removes some heat but the flow seems restricted which usually occurs at thermostat.
COMMENT by , February 13, 2012
I agree thermostat is failing. Thermostat cost you about $8.00 to $11.00.
COMMENT by , February 16, 2012
thank you both. I've had the thermostat in a pot of water. Still hasn't opened. But not full boil yet. The last 2 cars I had did the opposite, They would get hot when idleing, but cooled down when driving. And cranking up the heat only made it worse. Thanks for your help. I bought this car 2 weeks ago and havn't drove hardly any. God Bless, and have a good day.