Thanks for the views and advise.

I'm having trouble with my cooling system. I've replaced the radiator, water pump, Thermostat and radiator cap to no avail. I don't think it's a head gasket problem, because I've ran a block test and checked the oil/exhaust, all came back negative.

The problem is that coolant is not going back into the system, once it enters the reservoir. Popping the cap and spilling coolant.

During an acceleration, the reservoir cap would pop and the engine would start to overheat. Once I changed the water pump it stopped over heating, but the cap still pops.

Any advice? At this point I'm thinking it could be the reservoir cap, but I wanted to get your input.

Could be too much air in the system.

You don't say how many miles, but you still could have a bad head gasket. Not so it burns coolant, but letting cyl pressure inter the cooling system, pushing coolant into the over flow tank.

Thanks for the advise. I just had the check engine light go on for P0174. I might be too much air?

Also I was talk to another mechanic who said it's probably the head gasket.

It's pushin 210k miles, so it's on it's down. Maybe it just multiple problems and not just one. Idk. But I really appreciate all the help.

Everything on the 3.0 cooling system runs uphill towards the upper radiator hose, and air rises, so it's unlikely that air would be trapped in your system.

Your reservoir cap popping off is a classic symptom of a blown head gasket because the exhaust gas leaking past the gasket pressurizes the cooling system above and beyond normal pressure. Blown head gaskets are a common problem on the 3.0 engine, so that's likely what's causing your overheating problem.

My 2000 is starting to overheat, and I swapped out the t-stat and water pump and it still overheats, so it's likely that I've got a blown head gasket. We're not allowed to work on our vehicles in the area that I live so I'm going to have to have the dealer put in new gaskets, and I was quoted a price of $1200.00, which bums me out. :-(

I'm betting on a blown head gasket.
Sounds just like what my ranger did a few years ago.
Sorry.
But I got it repaired. Runs great.

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1800 for mine. Included coolant a new pump, a new rod, cleaned the heads, a new battery and a new plug. And a oil change! Still a lot cheaper then another used vehicle.

Oy, $1800. I'd attempt to do mine myself and save some money but I live in a mobile home park and we're not allowed to work on our vehicles in our driveways, so it's off to the dealer I go. Oh well, easy come easy go, right?

These 3.0 motors are known to blow the head gasket. Welcome to the club, I had to repair the head gasket on mine 5 years ago and it cost $1200 back then.

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93 Ranger XL 3.0 V6
-Tint, wheels, K&N filter, Flowmaster super 44.
04 Mustang GT Vert.
-Tons of mods, supercharged 392/393

Find a private mechanic to do it. Just say NO to the stealership.

Rules are made to be broken.

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FOR SALE 1994 Ford Ranger 3.0l V6 4x4 Automatic
2015 Ford F-150 Supercab 2.7l Ecoboost V6 4x4 Automatic
2012 Ford Focus 2.0l i4 Automatic