92 F 150 5.0 ext cab. After replacing all the hoses, water pump, thermostat gasket, & checking freeze plugs & radiator I am loseing 6 ounces of coolant in 40 miles.Also new rad cap. Pulled all the plugs & they looked like new since I put them in 4K miles. Ran a compression check & all the same. give or take 5 lbs. Stuck a clean white swab in to each cylinder, no mositure. Is the intake manifold leaking?A little white smoke on a cool humid day, not thick. No milky sludge or brown crap in oil. Any ideas how to identify heads , head gasket or intake manifold is the problem.

 

If you don't refill it will it continue to lose another six ounces every 40 miles? I had an engine once that insisted on running low on coolant all of the time. none in the reservoir and about 2 inches low in the radiator. If I didn't fill it back up it would quit losing coolant and run at normal temp at that level forever until I couldn't stand it anymore and filled it back up just to have it run itself back down to where it wanted to be.

 

Buckarcher is right. Try what he says and see if your system will stablize.

 

It keeps using coolant. Early today ran the engine till hot & pulled 4 hot plugs out.No steam Or mositure at plug hole or on plug. Ran the truck again & pulled second bank & no mositure.Still get some sweet smoke at exhaust. Is this what you would expect from a leaking intake manifold? On my Bronco II I even got steam out of the add oil hole. None here but the Brono II had badly cracked heads.

 

You may have a blown head gasket. The coolant is getting into the combustion chamber and that's why you get the sweet smelling white smoke.

 

Do you have a automatic tranny?
Check to see if the coolent is is the transmission.

 

Could not fix the problem with out tearing the engine apart. My 93 Ford Aerostar started doing the same thing. So traded them both in. I have factory shop manuals, a new Ford 4.0 water pump & thermostat with gaskets for sale just incase anyone needs them. Also two boxes of Ford 5.0 thermostat gaskets sent to me by mistake. Ten in one box & 9 in the other.The Aerotar manuals are for a 95, except the EVTM which is for a 93.