giro
New member
I took my 4runner out for a test drive this morning, after fixing several things post-fan explosion. I went ahead and replaced the thermostat yesterday, since the fan had sliced the coolant return line and I needed to add coolant. After replacement I filled up the fluid in the radiator, and put some in the antifreeze overflow thingy.
But it was then dark, so I didn't run the truck.
Today my test run was to head to our soon to be rental, which is up 800 feet from our house over 3 miles or so. I don't have a fan, but with temps at 35° or so, I wasn't too worried. I took it easy, and watched the temp gauge. Strangely, it stayed off the low end for quite a bit, over a mile. Then it jumped up to 50%, and kept climbing. At 75% I pulled over. I also turned on the heater, and it just blew cold air.
After a minute I headed down the hill, using brakes instead of the engine to keep is slow. The heater blew cold air until just before getting home.
What I'm thinking is that there was a big air bubble that was back by the water temp sensor, and also either in the heater core or whatever decides if the heater core should get heat. When the temp on the gauge changed so much, that was the water temp sensor getting coolant. And then the heater didn't start blowing hot until the heater core was given some hot coolant. It might have pulled in the extra antifreeze then, though the FSM makes it sound like that normally only happens when off and cooling.
Does that make sense? A smaller, shorter, flatter test run 3 hours later seemed fine. I'm thinking things are fine now. But I wanted to get ideas if there was something wrong. I was worried the fan might have sliced the temp sensor wires, but it looks like that's back behind the engine.
But it was then dark, so I didn't run the truck.
Today my test run was to head to our soon to be rental, which is up 800 feet from our house over 3 miles or so. I don't have a fan, but with temps at 35° or so, I wasn't too worried. I took it easy, and watched the temp gauge. Strangely, it stayed off the low end for quite a bit, over a mile. Then it jumped up to 50%, and kept climbing. At 75% I pulled over. I also turned on the heater, and it just blew cold air.
After a minute I headed down the hill, using brakes instead of the engine to keep is slow. The heater blew cold air until just before getting home.
What I'm thinking is that there was a big air bubble that was back by the water temp sensor, and also either in the heater core or whatever decides if the heater core should get heat. When the temp on the gauge changed so much, that was the water temp sensor getting coolant. And then the heater didn't start blowing hot until the heater core was given some hot coolant. It might have pulled in the extra antifreeze then, though the FSM makes it sound like that normally only happens when off and cooling.
Does that make sense? A smaller, shorter, flatter test run 3 hours later seemed fine. I'm thinking things are fine now. But I wanted to get ideas if there was something wrong. I was worried the fan might have sliced the temp sensor wires, but it looks like that's back behind the engine.
