atticus

my 4runner is overheating very quickly. it just started about a day or two ago. i put in more antifreeze and its still doing it. any diagnostics on this problem?

kunal

Shane

If you're losing coolant then definetly check for leaks. If you don't have any leaks it's probably the thermostat getting stuck closed.

WatsonMD

Make sure the drain plug (plastic) hasn't taken a hit lately and gotten cracked or broken. Also, check the top and bottom hoses - especially at the ends. Look at the water pump and see if the weep hole or bearing area is showing signs of a stain. Finally, it is relatively easy to do - replace the thermostat and gasket.

When I tore down the front of the engine to replace the timing belt, I found a small area on the side of the radiator that was weeping coolant - not very much. But, something to keep and eye on. If you can't find a leak in the usual places, try removing the fan shroud.

Your not "making oil" are you; ie getting coolant into the oil by a cracked block or head?? Check the oil to make sure it's not frothy or has water in it.

Best of Luck
Andrew

jx94148

A little more info will help us help you. Is the gauge reading high only, if so when, at startup, on hills or under loads? Is the coolant catch resorvoir filling or overflowing? Any leaks?
Does the heater work well?

Could be Stuck thermostat, bad gauge, blocked radiatior, bad water pump, blown head gasket, bad radiator cap, or a few other things. Post the symptoms, conditions, and indications of overheating please.

BTOWN4RUNNER

I have heard that a bad head gasket causes some symptoms similar to what you are experiencing. I would maybe check into that! Just a thought (I am by no means mechanically inclined ) :beaver:

-Ryan

samspade77

Hi dude,

Don't jump to any conclusions until you thoroughly check out the cooling system. The first thing you should do is pressure test your cooling system for possible leaks. It could be any of the cooling system hoses, radiator, water pump, heater core, etc.. If you don't have a pressure tester, then take it to a shop you can trust. A quick check for possible head gasket problems is check your oil dipstick. If it looks like a chocolate shake, then you probably have a leaking head gasket (coolant/water gets into the oil). The thermostat could be stuck closed, not allowing coolant to flow into the engine block. If this happens, the cooling system cannot hold all of the pressure built up and releases it. Usually it will push it out from the radiator cap. An easy way to see if the thermostat is opening is turn on your vehicle. Next, hold on to the upper radiator hose. When the engine reaches running temperature, the thermostat should open casusing the upper radiator hose to get extremely hot! Also, a bad radiator cap can cause the cooling system to leak. If the rad cap gasket is hard and cracked, it won't hold enough pressure in the cooling system--thus causing a leak. If you can't find a leak and don't have the tools to help you, don't hesitate to bring it into a shop. You don't want to overheat the engine causing permanent damage.

Good luck,

SS77

samspade77

Hi again,

Did you recently have any work done on your cooling system? Also, NEVER add straight antifreeze to your cooling system. You want at least a 50/50 mixture with water. The antifreeze does not cool your engine, the water does. Antifreeze has chemicals to prevent corrosion and rusting within your coolling system. It also prevents the water from freezing.

Good luck,

SS77

samspade77

Hi again and again,

I keep remembering things, so bare with me. Is your radiator fan coming on? When the engine is running hot, the electric fan turns on at a pre-determined temperature. If the fan does not come on, then your engine can heat up very quickly. The simple way to check this is start up the vehicle, and just watch the fan. Usually a bad fan relay is the problem. However, it could also be a bad fan motor, or a damaged wire.

Just trying to cover all bases,

SS77