Howdy, I just purchased a 1989 F-150 with the 302 and was told it over heats because of a bad headgasket. I started the truck with the radiator topped off and drove the truck for about 10 minutes then it started to overheat. I shut the truck off and immediately the coolant filled and poured out of the overflow tank and all over my garage floor. Soooo, why would the coolant pour out after I shut the truck off and not before?
I pulled the thermostat and it works properly. I looked at the head where the PO said it leaks and it was dry. I am stumped by this, maybe it's the water pump?

Help a Brother out

 

The reason the radiator over flows when you shut it off is because the water heats up more because it's not circulating anymore. It expands from the heat of the engine block then overflows.

The truck is getting kind of old and may need the radiator roded out. Or buy a new one. The tubes can get clogged really bad on old trucks.

It's not the water pump because they dump water out of them when they go bad.

Another thing is to buy a kit from the Snap On tool man that shows exhaust gases in the cooling system. I had this problem one time with a cracked head and it told me the truth.

Are you a black neggro like me? I ask because you said "Help a Brother out."

 

Nah, I said that because I feel we are all part of a large extended family.

Thanks for all of the info I will check them out ASAP.

 

What kind of shape is the radiator cap in? An unpressurized system has a much lower boiling point than a pressurized system - IIRC, a 50/50 mix of coolant will boil at about 227degF unpressurized, and 267degF under 15psi pressure.

Suggest if the head gasket were leaking, may see air bubbles percolating in the coolant recovery tank, as the cap relieves the pressure build-up caused by the air/exhaust gases being pushed into the coolant system.

Your radiator may have its flow restricted, as CaptainWaifers said. Be sure the thermostatic clutch on the radiator fan is working properly - give the fan a good spin (with the engine off, of course) - shouldn't see it freewheel more than 1/2-1 turn. Also be sure the radiator doesn't have any significant external airflow restrictions, such as bugs or debris.

Good luck, and keep us posted on what you find.

 

Today I warmed the truck up real good and observed bubbles percolating in the coolant recovery tank, so I guess that answers that question. I will keep you all informed with the findings.

 

I FINALLY removed the heads today and confirmed the bad gasket. I will clean them up and make sure they are true.

 

Inspect the heads very carefully for cracks.

 

While you are at it check to make sure you don't have the aluminum housing for the thermostat, if you do replace it with a the steel version.

 

Have a machine shop check for cracks in the head between valve seats. With valves removed, cracks are the most evident. A valve job and head surfacing is in order at this time, money well spent with no regrets later. Don't recall if a newbie or not, this is a Ford not a GM. GM mechanics are air heads and won't follow instructions. The head gaskets on a Ford V-8 are interchangeable left or right as is a GM. Its front to back that is the key to remember. The water passage from block to head is at the back of the engine, notice the large passages in the gasket at the opposite end of where it says FRONT. Ford puts that there for the mechanics who can read, not saying GM mechanics can't, BUT! Don't normally like to stir things up.

 

I called around and found a local guy who will magnaflux and pressure check for cracks, 3 angle valve job, and resurface for $300 bucks.

Is this a good deal?