HI!
After replacing the thermostat im getting wired symptoms of blown head gasket but before i start taking everything apart wanna make sure im right.
First of all no water in the oil ...
After filling the radiator to the top and starting the engine i have water puring out of the radiator but not right away after about 3-4 mins engine isnt even worm yet.....put the cap on and i see bubles in overfill tank...temp goes up almost to the red on the gauge .....i hear bubles in the radiator ,excesive water goes in the the overflow tank sometimes it will over fill the tank...temp goes down ....if i keep the car running it will keep the right temp it will not overheat...but if i shut it down and let it cool off same thing will happen again ....
Could this be just a bad radiator cup? but where is all the prassure comming from? clogged radiator? bad water pump? lazy new thermostat or is it the head gasket? ....
The old thermostat was stuck open all the time ...it wouldnt overheat ..nothing would leak out of the overflow tank.....and it didnt seam to have all that much pressure in the cooling system to force the water out ...im confused ...dont really feel like pulling the heads but i will if i have to

Any input is really apreciated...btw its 91 3.0

dom

 

A couple of thoughts: Did you use a correct 193-195 degree thermostat? What Temp and brand is your new thermostat? I would use a new Motorcraft radiator cap. I have used a 13LB. Motorcraft cap on my 3.o v6 (says "RS62" on the cap) with never an issue. Replace new, every 3-4 years, they run around $8 at the Ford dealer, and are worth every penny. Since you said your thermostat was stuck open, the cooling system possibly never got HOT enough to scrub and steam clean the inner cooling system of your 3.0. I would flush your cooling system completely, as you probably have a lot of setiment and gunk built up. What did the inside of your top radiator hose look like, when you removed it to install the thermostat? When you say, you have water pouring out of the radiator, but not until 3-4 minutes, where is the water coming from? Also, when you are running the engine, make sure you have the heater on, and fan on high. This will help purge the system of any small air pockets, sooner, rather than later. Although it might take a while. Some vehicles, if the front is up on jackstands, when adding water, then coolant, helps to remove any air out of the system. Anyway, I would re-flush, use a new Motorcraft cap, then write back here with any other comments of what is going on. Dom, it's a 3.0 v6 Aerostar, correct?

 

are there any tiny champagne size bubbles rising up in fill hole only with engine running? bubbles = blown head gasket

is new thermostat installed correctly with main spring body toward interior of engine and back into thermostat housing?
if installed backwards, cooling system will try to relieve pressure backwards thru block and water pump and into return fill side of radiator
take thermostat off and test in pan on stove with thermostat to measure opening temp.

your block, heads and cooling system are very likely contaminated with cold running products from failed open old thermostat....back flush engine block thru outflow rad. hose with garden hose on full pressure...back flush heater core with low pressure...back flush radiator thru fill hole blocking off bottom hose-best to remove radiator to turn over so it will drain out top hose inlet

flush crankcase that is loaded with sludge cased by failed open thermostat...put in 2 quarts of engine flush or kerosene...run engine at idle for 10 minutes....let set overnight....change oil with 1 qt of Rislone and 4 qts of your regular oil and new filter....repeat in 1k miles.