I have an awful grumble when I start my 94 3.slow equipped 4runner cold. It's a low and loud growl that goes away when the engine temperature gets to full operating temp. Anyone have any idea what could be causing this annoying but otherwise a-symptomatic noise? Should I be considering replacing my thermostat? The noise started about a week after I had a new radiator installed, and my transfer case serviced... but I've had a new radiator blow a water pump on my fullsize blazer before... Anyone have this noise? Is it something I should be extremely worried about? My truck is going to the mechanic next week to have a marlin crawler 2100lb clutch kit, grade 8.8 pressure plate bolt upgrade, and brand new master and slave clutch cylinders. I would love to figure out what this problem is and give my mechanic my truck saving him the time of rooting around, but he's really good at what he does and I feel he can get it taken care of if I don't figure it out beforehand anyhow.