Engine heating up on 94 explorer

Big air pocket ??? On the explorers I usually bleed the air out by pulling 1 of the heater hoses off and fill it till it runs out of the hose.

Might be a blown head gasket letting combustion chamber gases into the cooling system.

There is a test that checks for gases in the antifreeze.

You might pull the radiator cap off, warm the engine up, make sure the radiator is completely full, and watch for bubbles - you might actually see them given you blew the radiator.

I do a variation on that which requires 2 people- start with a cold engine, completely fill the radiator, start it up put 'er in gear but keep your foot firmly on the brake. Rev it up slightly- maybe 1200 rpm, enough to keep it from stalling, and load the engine by slipping the clutch if it's a manual. If you have a blown head gasket which is letting exhaust gasses into the coolant, you'll see bubbles escaping from the radiator. It will look like it's boiling.

Loading the engine just makes it more clear by increasing the amount of exhaust gas in the coolant, and it will leak when cold, so no point in warming it up first.

-Paul

Some possibilities: Radiator fins plugged- grass seeds, bugs, cottonwood fluff, you name it. Fan clutch not working, or belt slipping (not likely from your description.) Thermostat stuck closed- I'd go with this first; it's an easy, cheap fix. Water pump impeller rusted away- I'd say this is likely too. Not as easy and cheap as the thermostat, though. Plugged radiator cores- try draining some coolant and see what comes out. Someone else suggested head gasket, but you'd have some other problems, too.

Chuck

snipped-for-privacy@yahoo.com wrote:

To me it seems like it's probably the water pump. If you squeeze the top hose after the engine warms up you should be able to feel some pressure, especially when you let go of the hose.

I also seem to recall something about air getting trapped in the radiator which might cause lack of cooling. If you take of the radiator cap and let it run for a while the air should come out. I don't think there is another procedure for bleeding air from the system. A leaking head gasket can cause bubbles in the cooling system too.

I solved an overheating problem on my '91 with a new radiator cap.