I have a question as to how to test a thermostat that is weak but not failing. I can hit 80-85C and stay there but my stop and go commute makes it hard to judge as opposed to a steady highway run.
I was idling the car and checked around 65-70 C the other day which lines are hot/cold. It was about 55F outside.
(refer to image of cooling system below)
I noticed that the left side coolant hose to radiator (that runs into the thermostat) was cold. (near the number 1/2 in diagram- blue colored in diagram)
The right side one to radiator was very warm (near "16" big red colored hose) and the radiator itself was hard to check because the AC one is in front of it.
Being that the coolant flow is from block to right side of radiator, through radiator and exits left side to be taken into the thermostat I'd think if my thermostat was shut (below 80C or so opening point), the red hose on the right would be much cooler- unless it heats up by sitting on the "hot side"
If the thermostat was prematurely open, the left side that goes into the thermostat would be running warm- right?
If anyone has recently done their thermostat on their 35d or 335d could check these 2 hoses at a coolant temp before 75C or so- but above 60, it would be helpful to diagnose a thermostat that opens early (or "leaks through")
