Help!!!!more Overheating Problems

[CRUZIN66]

I JUST DROPPED IN A NEW 302, AND IVE HAD NOTHING BUT PROBLEMS. HERES THE DEAL. STANDARD WATER PUMP, ALUMINUM RAD, 180 THERM. 7 BLADE FAN, 16 LB CAP. CITY DRIVING NO PROBLEMS, UNTIL I GET ON THE FREEWAY. ENGINE STAYS AT 180 THEN THE PRESSURE RELIEF ON THE CAP BLOWS AND MY TEMP SKYS TO 230. I HAVE TO PULL OVER FILL THE RADIATOR BACK UP THEN ITS FINE FOR AWHILE. THEN BAM!!!! THE DAMN THING DOES IT AGAIN. I NEED HELP PLEASE. AM I MISSING SOMETHING??? DO I NEED TO GO TO A 19 LB CAP??? THIS IS MY DAILY DRIVER AND ITS DRIVING ME CRAZY. thx,rob

 

[Socal Tom]

Probably a leaky head gasket. What's happening is you get on the freeway, then your pumping pressure into the system, and it's blowing out the water. Fill up the radiator, let it idle until it warms up, the watch to see if it keeps bubbling water out.
Tom

 

[asabadin]

make sure all air pockets are out of your cooling system. next try a new cap. any oil in your coolant? Does not sound like head gasket issues. ask scott he had the same problem. www.americanbronco.com

 

[76Broncofromhell]

Sounds like a blown head gasket. Are you sure they are in the right direction? If it's losing fluid and pressurizing the coolant system it's a head gasket. Did you surface the heads when you put the engine back together?

 

[Skuzzlebutt]

Could be a defective cap.
Or a head gasket problem. Theres a simple test to see if there's any HCs in your coolant to indicate a gasket prob.

 

[Skiddy]

Did you build it yourself? or did you get a whole new rebuilt, if so I would contact the builder.

 

[74bronc]

make sure your lower radiator hose has a spring in it. They have a tendency to collapse when the engine is really working it, like on the freeway. Also, if you built the engine, are you sure you got the head gaskets on the right way? There is a right way and a wrong way on a SBF? If you didn't build the motor, you may want to ask your rebuilder.

 

[chuck]

All caps are not the same. They are made for diff depths of filler neck. Your 19 lb cap may be just touching the seat where it should seal so a little pressure will cause it to bypass. Measure the depth. Also you do have a coolent recovery bottle I hope. If not that is my first guess.
When the engine warms up coolent and air will go out then when it cools down the engine will suck the coolent back in if you have a recovery bottle, if not it will suck air back in.

 

[JWMcCrary]

The problem you are describing is exactly the problem I had on a Mustang (289)with a head gasket on backwards. It would idle fine right around the temp of the thermostat, as soon as you got on the road it would get extremely hot, the top radiator hose would swell up and eventually it would blow just about all the water out. I would try the other suggestions first, just be careful and don't ruin your engine.

 

[CRUZIN66]

thank you everyone for your help. i will post back when i figure it out. rob

 

[mtkawboy]

The front marked on the head gasket goes to the front whether its upside down writing or right side up. Ive seen dozens put on backwards on one side because people thought it must be wrong when I was a dealership mechnic. I could be wrong but thats where I would look