hey, just bought a 1980 toyota pickup with a 22r motor in it. Recently, it started overheating on highway and liquid was gushing out my radiator overflow.
Im wondering if it could be a clogged thermostat? Hoping, since its a cheap fix. Because at the moment i cant drive it for long without it heating up way too quickly.

 

Take the cap of the radiator, start engine to let it warm up. Keep watch to see if the thermostat opens, as the water will move across the radiator. If not, replace thermostat

 

Are there any other symptoms, like water in the oil, or . . . ?

 

Not unless you have a busted head gasket. If the water is not circulating in the radiator, means the thermostat is stuck closed, so the only place the expanded pressure and water to go is through the overflow

 

A compression test should tell you if you have a head gasket issue. Before I would start looking into the head gasket, I would go thru the cooling system. As hot as it is around the Midwest, I could see some over heating, If you still have the original radiator in it, these radiators have so much gunk build up in them, it is a wonder that they can do any cooling. I have my radiators professionally flushed and the gunk that comes out of them is bad.

I have seen the temperture gauge drop as much as 25% when a radiator is flushed. The Prestone Kit will not clean it, it needs to be power flushed. I would check thermostat, timing,cap, water pump and maybe flushing the block as well. The Prestone kit can help with that if you have enough water pressure. When flushing the cooling system, it is a good time as well to flush the heater core. Use light pressure for the heater core. Those can be a pain to replace in these trucks. Cooling systems need a lot of attention on these as most have been neglected.

 

@lons81 thermostat doesnt open...going to flush radiator and put in a new thermostat.
thanks for the info, will update again after.