Re: Boiling radiator overflow?
A few things that you may wanna check (some already mentioned):
- Radiator Cap - If it doesn't allow the water to expand into the overflow, it can cause excessive pressure leading to high temps. It happens more often than you think. Remedy - replace....it's cheap.
- Lower Radiator Hose - If the spring breaks down, the hose can collapse under suction and essentially starve the engine of fresh, cooled water. Remedy - check condition of spring by trying to collapse the hose by hand. Also, rev the engine at idle a few times and see if the hose distorts more than normal.
- Fan Clutch - Wears out and causes the fan to underspin at idle or locks up and causes it to overspin at speed. Usually a cause of low speed/idle overheating. Remedy - check the clutch by trying to stop the fan with a folded over piece of cardboard (something rigid, like the flap of an oil case). If you can stop it or significantly slow it down with the cardboard, it's shot.
- Thermostat - #1 cause of overheating. Thermostat sticks, won't open, and essentially becomes a block a lot like a collapsed lower hose. Remedy - replace....it's cheap, or check with a boiling pot of water.
- Blocked Radiator - Leaves, bugs, and crap can build up in front of the radiator and prevent good airflow. Remedy - clean it.
- Broken Fan Shroud(s) - They're more than just protection from the fan. They help direct airflow properly. Remedy - replace.
- Water Pump - Can wear out over time and slow down water flow and/or begin leaking. Remedy - look for signs of leaking out of the weep hole (snout of pump, just behind pulley - this indicates a failed front seal) or at gaskets to the block. Remedy - replace as there's not much in the way of testing them.
Also, be sure to flush the cooling system whatever you do. Dust, etc... can float into the engine bay, settle in the overflow, and over the next few heat cycles, get circulated into the cooling system. Repeat this process over several years, and there could be as much garbage in your coolant as there is coolant.
HTHs
Hood
That would help a little. It's also about 97 here right now with lots'o sun. So that could be a contributing factor.
