over heated engine and heater blows cold air

[jictat]

I have a 1995 ford mustang 3.8, my problem is, after two or three miles of driving the temperature, the indicator passes the place where the thermostat opens and the fan runs then shows that the engine is overheated and the heater start blowing cold air, I took the car to the mechanic and he changed the thermostat and replaced the anti freeze, I drove the car again and it was the same the indicator goes almost to the end of normal, (never passes to the red line), heater blows cold air and after couple minutes it goes down again and works fine, thermostat and radiator fan works etc, heater works, is only after I start driving and the car warm up, I'm concern because I don't know what's goin on, and because the mechanic couldn't solve the problem.

I checked the engine when it happens and it doesn't feel overheated

Please help me.

Thank you

[xxxBlakexxx]

Sounds like a heater core problem...though I am not sure why your temp guage goes up. I would have started witht he thermostat too. You may have gotten a bad replacement thermostat...this kind of thing happens a lot with bad parts.

[91LX2Bfast]

Humm... it's strange that the car is overheating yet the heater is blowing cool air.
I blew 5 heater cores in my last '97 Tbird (don't ask Ford crap ) and it did have similar symtoms. So I agree with blake in that it could be a possibilty. Except when mine blew, I got "green" steam coming up behind the dash onto the windshield and coolant would run down all over the passanger side floor. So it wasn't hard to diagnose to say the least.
Another theory: As with most pre-'99 3.8's, headgasket failure is always a possibilty. That can and does cause overheating problems. As far as the cool heater air?????: Maybe if enough air is getting into the lines, maybe it could be building up in the heater core? Then there wouldn't be enough hot coolant to heat up the air?

[explicitone]

Originally posted by jictat
I have a 1995 ford mustang 3.8, my problem is, after two or three miles of driving the temperature, the indicator passes the place where the thermostat opens and the fan runs then shows that the engine is overheated and the heater start blowing cold air, I took the car to the mechanic and he changed the thermostat and replaced the anti freeze, I drove the car again and it was the same the indicator goes almost to the end of normal, (never passes to the red line), heater blows cold air and after couple minutes it goes down again and works fine, thermostat and radiator fan works etc, heater works, is only after I start driving and the car warm up, I'm concern because I don't know what's goin on, and because the mechanic couldn't solve the problem.

I checked the engine when it happens and it doesn't feel overheated

Please help me.

I would try 2
things first there is a possible air in system try this take the rad. cap off and start the car and let run until the tremo opens and will be able to tell cause the level will go down and then just add more to keep it full.(called burping the system)

next I would change the coolant temp sensor its in a coolant pipe going over the lower intake manifold that could be going bad as well

Thank you

[95mustanggt]

I agree. Make sure there is no air in the system. That would cause the heat to disappear.

I'd also do a compression test. You could have blown a head gasket which would cause the low coolant level and the heater to stop.

Is there coolant on the ground?

Have you had your codes checked? It's easy to do on the 95 5.0L but on the 3.8 you'll probably have to take it in or buy the code reader.

[jictat]

I'm going to try that, any way if you have more suggestions do not hesitate in write them here

Thank you people, you guys are the best.

[jictat]

No there is no coolant on the ground

[moosejaw]

Head gasket pre-eminent failure. Check the other post you made in windsor.


Mike