cooling issue on 84 f150 w/302

[elongoria]

I bought a beater work truck, and I'm having cooling issues. It ran on the hot side the day i drove it home. It was a lil low on coolant so i filled it up and drove it another 20 minutes home and it still ran hot. 2days later (not driven since) the radiator was still full. I drove it down the road and it ran hot after about 15 minutes driving down a hiway at 60mph. The temp came down twice while at steady speed, but not consistant. It will idle 45 mins to an hour and be fine. But it starts running hot going down the road. I did notice about 1/3 of the condenser fins were bent over, but didn't seem like enuff to make it run hot. Turning heater on didn't help... actually made it seem worse lol.

[Dacotua]

Some old 302 early 80s had cheap water pumps with plastic impellers.

But since yours idles fine but heats on driving, I bet your radiator is clogged

[Venom]

I'm betting on the radiator being clogged.

[elongoria]

Just replace it, or is it worth a try to flush it?

[Rreemo]

Almost always ends up being a clogging radiator (like said above), when they get hot going down the road but not at idle. I've also seen this happen when the spring is either rotted away or missing entirely in the lower radiator hose. Without that spring the lower hose will collapse itself at higher RPM.

[AdRock]

I agree with the clogged radiator assessment. If you happen to see that it looks like someone has put stop leak in it then replace the thermostat also. I worked on an old 86 f150 that had the same symptoms and the thermostat was gummed up horribly with stop leak.