Evidently, when the thermostat is closed, there is suction on the lower side of the radiator from the water pump trying to pull fluid out of the radiator, AND the block. The suction pulls from the water pump, (through the lower hose with the typical spring that lower hoses usually have), to the lower side of the radiator, through the radiator, and then suction is felt at the top hose, then the top hose collpases. The t-stat is basically at the end of the top hose, and since its closed, the suction has no where to draw from except the block, so the top hose ***** in. This probably does not occur very often in normal operating conditions. The thermostat is only closed during initial warmup, and never closes again unless there is greater extraction of BTUs from the engine than needed, causing the engine to cool below designed operating temperature. When this happens, only at higher rpm's in cool conditions, the car is out on the road, and no body notices the top hose collapsing! I'll bet this happens on a lot of cars, but isnt seen unless a car is reving high on the dyno, with forced air being blown into the radiator, causing the cooling system to extrat more BTU's than the engine is making, and that under high rpm's, when the water pump is turning very fast, making a lot of vaccum. That situation is artificially created, and does not occur like that in actual use, even under heavy loads and high rpm's, (think t stat open from the BTUs being created). The forced air flow is the abnormal condition, and doesnt represent true driiving conditions. But there could be that odd time when you are reving at redline in a blizzard, there is extreme water pump suction, then the t-stat might close, and the hose could **** in....But when are you ever reving near redline under extremely cool conditions? And how long would you be spending at or near redline, generating all that high suction? Not likely very long. But it could happen, if all the conditions are right.
And if the hose collpases, so what? Its not like water flow to the radiator is needed at that time. With the T-stat closed, there isnt any water flowing through the top hose anyway, so the fact that it collpases under suction isnt important. The argument that the flex is wearing the hose out is weakly speculative, and the issue doesnt arise to recall status. When the t stat is open, there is
pressure in the top hose, it
will be open, it
will flow coolant, thats all you really need to worry about. Its ability to withstand pressure is the issue, not what it does under suction, thats a tangent. Efforts spent to keep it from collapsing are fruitless and misguided.
How many friends did I make today?
