Overheating

[SultanGris]

Motorcraft Gold or Zerex G-05 would be best. While it is possible that you still have some air in the system... the 70/30 mix is probably the issue.

A 50/50 mix provides boil over protection to 265 degrees.

Your 70/30 mix is only good to around 230... which is where the LS runs during NORMAL driving.

Interesting, what happens if you're straight water? Don't seem to be overheating. Cuz mine leaks so fast I'm straight water, not wasting money on antifreeze till the leaks stop, lol
Thanks

 

[joegr]

Straight water will transfer more heat than coolant (water + antifreeze), however steam will transfer very little heat. The LS wants to run at an average coolant temperature of about 200 F. This is average, so there are hot spots that are well over 212 F. When water boils, it expands greatly in volume, causing sudden high pressure in the cooling system, maybe more than the pressure relief can handle.
"Overheating" doesn't happen to well over 230 F. The designers must have counted on the system both being pressurized and filled with coolant, not water?

 

[SteveOwens]

Vee can't be seen unless the intake manifold is removed. I had this hose slowly leak, $$$ coolant wasted solving this one. Another mystery leak was the by pass 1/4 ID hose on the thermostat bridge piping, it would reveal the hose split only during hot sunner freeway driving. $ coolant wasted. If the plastic piping from the radiator begin to split which I replaced multiple times with 1.625" diameter copper tubing. Used copper because of the oil filter heater/cooler lines. I solder in the hose fittings after a drill and tap before the solder applied. Another fail is the thermostat retaining tab breaking. A 4-40 screw with a #43 drill bit size added strength to the tabs. The water pump has a aluminum impeller vs the plastic.
Only Moss Motors, Ltd in CA has this one. Substitute the exhaust mixing chamber with a Bassini X-Pipe! Most noticeable one item improvement in performance. Allows it to breath to 6k+.