Mildred Jones

iTrader: (1)

There are 2 seats in my LS1 thermostat. I know the seat near the return hose opens when the stat reaches it's set value. Can someone explain what the deeper seat is for or does? I am new to LS. I have installed a 6.0 in my 87 442. The stat is so far from the engine heat that it take a temp. over 220 to first open the stat then it runs between 185-180. Fan does it's job. FAST ez -ls is my controller. I have a 160 stat. I have not gotten the car out of garage yet. Still on jack stands. Thanks--Lee

joecar

The inner seat is the bypass (BP)...

when TS is closed, the BP opens easily to allow coolant from the block to go thru the pump;

when TS is open, the BP usually stays closed (i.e. is more difficult to open), this forces coolant from the block to go thru the radiator;

see attached coolant flow "schematic" I drew (I measured the spring rate and and surface area, from these I calculated the approximate BP opening pressures; and I traced the passages thru the pump, the circle and square represent the passages at the pump and block interface).

joecar

( when TS is open, if pressure difference across BP is sufficient to open it (10+ psi) then the radiator circuit has a serious flow restriction )

joecar

You should bleed out any air in the block (remove the hose from the steam-crossover tube connecting the heads, place a clear tube so you don't make a mess, watch the air passing out).