Mysterious radiator leak

mrsmengel

Desperately seeking a solution to the mysterious radiator leak in our Tacoma. The truck has 148,000 miles on it, and has been doted on its entire life. A couple of years ago the coolant began to randomly "disappear" from the radiator, yet there is no sign anywhere of leakage. We had the radiator checked, flushed and filled -- twice, at two different shops -- and it was declared fine. We have replaced the thermostat. We have replaced all the hoses and belts. We have replaced a head gasket and a cracked head (which, frankly, the need for which we're suspicious about, but we've moved on) and now we've put in a new radiator. And still, the radiator turns up dry. The overflow reservoir remains full. A side note to all of this is that we (meaning I, not the husband) use this vehicle to pull a vintage travel trailer around the country. Dry weight on the trailer is about 1,300 pounds, plus some gear. Husband initially wanted to blame this on the trailer (meaning, on ME), but as the truck randomly overheats regardless of whether it's towing (and even when HE is driving), he has backed off of that. The truck has overheated three times this winter, including one morning when the temperature was 18 degrees. Please help!

skipbond

So they pressurized a full system and nothing was leaking anywhere? I had a small radiator leak that was a small crack in the plastic part of the radiator. Problem was it evaporated and left no clue. Until it finally just sort of exploded open then it was obvious. Yours sounds like a freeze plug leak if it isn't visible and would most likely only leak enough while running.