Bleeding air out of cooling system

[yakko]

92 F150 4.9 4X4 (straight six)

Stepson just bought this truck Friday from a person (no take backs). He doesn't get his actual license until next week, so I'm the one who drove it home (which took about four hours). It never overheated while I was driving it.

When we got up to the farm, he took it out to drive it around the farm and very quickly it started to overheat. He said the only thing he did was put it in four wheel drive. The overheating was a gurgling noise and it was pushing into the reservoir. The temperature gauge was acting funny also. It would show no heat while the truck was running normal and then when it would overheat it would go up to about halfway. Any ideas on that?

It's been overheating ever since then. Today we replaced the thermostat but that didn't help.

I want to bleed the air out of the cooling system, so my questions are...
is there a bleeder valve on the cooling system?
does anyone have a procedure that has worked well for them to bleed the cooling system on this era of F150? I've heard of parking on a slight hill making sure the radiator cap is the highest point and running it like that with the top off, stop, fill, repeat. Is that my best option?

Thanks guys, my stepson and me appreciates any suggestions or advice.

[RahX]

You should probably start looking for a coolant leak. It shouldn't loose coolant. As for bleeding, the truck on an incline with the cap off should be sufficient to bleed it.

[yakko]

I haven't really noticed a coolant leak. I was just hoping to get any air out of the system.

Anyone have any ideas about what could be causing the overheating? Changed thermostat. Bled air out. Water is flowing so not the pump. Doesn't seem to be losing any fluid. Temperature gauge seems to be messed up.

Any thoughts would be welcomed. Gonna check the radiator's fins tomorrow as good as I can. Maybe he did something and now they're all bent up and not flowing.

[Jerry Irons]

Originally Posted by yakko

I haven't really noticed a coolant leak. I was just hoping to get any air out of the system.

Anyone have any ideas about what could be causing the overheating? Changed thermostat. Bled air out. Water is flowing so not the pump. Doesn't seem to be losing any fluid. Temperature gauge seems to be messed up.

Any thoughts would be welcomed. Gonna check the radiator's fins tomorrow as good as I can. Maybe he did something and now they're all bent up and not flowing.

The temperature gauge may or may not be accurate, it has it's own sending unit that probably plugs into the block that is tough to get to. (I have a 96 that has had a broken sending unit for some years) I would say that something got jostled/etc when it was put in 4 wheel drive. (not that is was his fault, it was going to happen eventually) Maybe internal block in radiator? Sometimes they just get old and restrict flow, I had one go bad in a dodge shadow once where the temp would just gradually climb until the car would overheat. It's all a crap shoot here on the internet. Is the upper radiator hose hot when engine has warmed up (ie proper flowing coolant) Can you squeeze the hose? Just guessing at this point.;
If it isn't losing fluid, then it isn't flowing right... something is blocking it somewhere. How bad did it overheat?

[yakko]

seems it was the radiator. we replaced it and the overheating problem is gone. I just hated replacing parts without being sure of which part. After taking out the old radiator, it was pretty obvious it was a problem. The fins just kind of flaked off if you rubbed them.