Recently while I was in San Francisco, having open heart surgery to correct a previously unknown Birth Defect in my ticker, some JERK stole my 88 4Runner out of the garage at the hospital. When the San Francisco Police Department found it the next night (darn good service), besides the fact that the thief had taken our suitcases and electronics out of it, we discovered that when running "Yoda" on the freeway, it would overheat. I recently did a head job on it, replaced the headgaskets, replaced the wiring harness to the knock sensor, thoroughly flushed the radiator, and after this work it passed California Smog (yeah) and ran really good. After the thief drove it till it ran out of gas, it now overheats. I took out the thermostat, reflushed the radiator, ran a can of really good stopleak, gave it a good water flush, refilled it with the right coolant at the right mixture and it runs quite well around town, however, it overheats to about 90% of hot on the cooling gage. It does not use or expel any coolant, what little it does goes into the overflow tank and as it cools the coolant goes back into the radiator. It has no evidence of a head-gasket leak, nothing coming back thru the radiator, no evidence of any water in the oil, or oil in the water. When I turn on the interior heater on high, the engine cools down about 20% on the water temperature gage. Since it only seems to overheat on the freeway, (outside temp between 60 and 80 degrees) I deduce that it is not the clutch fan, no thermostat issues, it must be the radiator. But before I replace the radiator with a new one, any thoughts??? thanks in advance

 

That sounds EXACTLY like a clogged radiator. Somehow got clogged in their mad dash??

 

Sounds like a clogged radiator to me,had a very simular situation in my 87 4runner 22re a few years back.would get hot driving around town or highway and wasnt loosing water, i would turn on the heater and it would cool off.sent it to a radiator shop and they said it was 80% clogged