Im stumped here.............. I am not an expert mechanic, but I am a fair shadetree. My truck is running hot. It doesnt do it immediately, it takes a while for it to build heat.

I have replaced the thermostat, flushed out the radiator and heater core, replaced the radiator cap, and it is still heating up. With the cap off, and engine running, I can see the water circulating when the thermostat opens, so I know both of those are working.

After I did all that, I let it set in the driveway and run about 2 hours. It didnt heat up in the driveway.

Im wondering...............Is the radiator partly blocked so water isnt fully circulating and cooling? I am alos wondering if I have a blown head gasket and pumpin heat into the water jackets? Any way to find out without just replacing the radiator? Will a pressure check tell me if the gaskets are blown?

Any help would be appreciated! Thanks in advance!

 

Yes. A pressure check will tell you if you have a blown head gasket. It will also show any other leaks. Is this the original radiator? You can have a partially clogged radiator and still show water circulating. Good luck.

 

maybe under load the lower radiator hose is collapsing and restricting the flow. after the engine has reached normal temp try reving the engine up and checking the lower hose. I've seen them suck closed before after the spring inside corroded away.

 

Is the coolant just streaming past the rad cap hole or is it bubbling/gurgling past the hole ?

 

Need a bit more info;
is it actually boiling over, or is the gauge just running high?

when the gauge goes up does it get to a certain point and stop or does it just keep going until it pegs the gauge and boils over?

is it getting hot around town or on the hyway?

does your heater blow good heat all the time?

 

I have had good luck checking head gaskets by pressurizing the cooling system and removing the sparkplugs, wait a few minutes, while keeping the pressure up. Then have a friend or 2 look at the sparkplug holes while u crank the engine over. If one of your friends gets wet and pissed off, u have a blown head gasket. the wet hole is the leaking cylinder. Also check the temp sender. I have found some with crud on the sensing bulb. Remove the sender, wirewheel it clean, and reinstall with thread sealer. Recheck the gauge..Also pressure check the cooling system and cap. If u have coolant on the passinger floor, your heater core may be leaking. It may be a good time to install an aftermarket gauge. The hardest part is trying to remove one of the old rusty pipe plugs to install the new fittings and sender. GOOD LUCK HUNTING DAHMER

 

I did this conversion on my old 74 Bronco that I put a 351w in, I know some of my friends had done it to their 302's with great results.
http://classicbroncos.com/manifold_cooling.shtml

 

I'm in New England, so we don't get the heat you guys get in the south, but I've never had a 302 or a 351W that ran hot when the cooling system was in order. I actually had one,(85 f-250 302), that I made the mistake of putting the 2 1/2' aluminum radiator in when the old 1" core failed and the damn thing wouldn't warm up in the winter. I ended up trading radiators with a friend that had the smaller radiator so I could get some heat out of it.

Are you guys in the south haveing overheating problems with these things?