Hi there!
Hope you guys not having any problems with your 4runners, but I do
So the current two things that are worrying me are overheating and some intermittent whining noise.
The overheating. It started recently, I noticed the engine normal operating temp is a bit higher than it used to be. I didn't think of it much, since i was in town and had no idea how quick it can be moving towards overheating when I go to forest roads and turn my 4x4 and low gears on. So right now when I go under load it overheats rather quickly and I have to stop to cool it down, it cools down pretty quickly especially when I turn cab heat on.
There was a thing happened like 4k ago. My cooling system opened while going up some forest road (one of the rear heater core bypass coupling failed), I have lost a great deal of coolant. I had some spare coolant, but not enough so I mixed it with water and turned around. on my way back I was overheating a few times but would stop before it get to red and cool down again. Made it to the parts store and got some coolant and added it to my expansion tank, I was loosing some coolant on the way because I had to reconnect my rear heater core to close off the cooling system, but the RHC lines were a bit leaky and I kept adding proper coolant as I proceeded home.
At home I flushed the system, filled new proper coolant and bypassed RHC again.
I have no idea if my system burst and current overheating are related, but Im looking for ideas on where to start chasing a problem.
Not loosing any coolant,coolant as red as toyota coolant can be,oil cap doesn't have any white under it, water pump was replaced 17k ago, hoses like 2 y.o., cap is under a year, radiator like 5y.o., fresh coolant. Have no idea if t-stat was ever replaced. need help and ideas.
Sorry for too many letters
Another thing is whining.
It would come up from nowhere. Cant make it to whine at will.
Sometimes it whines a bit at start, start moving it continues for a bit or goes away, today run an engine while parked and was given it a gas it would whine louder with higher rpms, foot off gas, whining going down but still it will continue in the background. One day it would start whining when going up the hill on 4x4 low, stopped, turned into 4x4 high and whining would stop. Later in the day whining come up from nowhere on a straight trail, i stopped, popped the hood, whining was coming from steering pump/ AC compressor side, moved steering wheel back and forth...nothing happened to the whining, played with AC on/off and whining stopped. turned AC on no whining, turned AC off..no whining. Went home, no whining for few days. Replaced AC belt tensioner and it didn't affect whining in any way. belts and timing belt were replaced like 17K ago.
Whining comes and goes. Need help chasing a problem.
Thank you so much guys.
Im sorry if it looks like waaay to many letters.