ISVs are normally very reliable units and not usually the cause of erratic idling.
Vacuum leaks are a frequent cause of idle troubles. Trace the vacuum lines that run from the throttle body and check all connecting pieces are in good order as well as the vac pipes themselves. Also check the short rubber connector between the camshaft cover and the plastic 'drum' above it - leaks here will prevent the engine from idling correctly.
Check the connection to the throttle position switches on the throttle body. The lower switch senses the 'throttle closed' position and engages the ISV.
If there are any doubts about the fuel mixture then get the car tested/adjusted for emissions.
Disconnect the ISV when the car is hot and see if there is any difference to the idle speed. Ideally there should be little or no difference if the idle speed screw on the throttle body has been correctly set for 950 rpm. If there is a large difference (and everything else has been checked) then leave the ISV disconnected and turn the idle screw until the rev counter is as near to 950 rpm as possible. Finally reconnect the ISV.
Look here>http://www.vwgolf-mk2.com/eclean_idle_control_valve0904.html
By braking it down and fixing all parts
if you are looking for the temperature sensor on a 3.9L, looking down onto the top of the engine, it is just to the left of the thermostat housing. it is small and has wires plugged into it. remove this plug and then using a socket and extension, remove the sensor, reinstall the new one and plug the wires back into it. coolant may flow out a little escpecially if the engine is still warm but its not much
symbol for screw down non return valve
while pushing down the valve with the finger, take out the actual valve and wipe off the metal with a towel or something like that. then, just put a tiny bit of grease on the valve and put it back where it would be (still pushing the valve down with the finger) and just move it around so it gets all over the valve. did you need help with oiling the valves too??
the valve transfers the heat to the valve seat (when the valve is closed)
If you start to be more active like excersise wise it usually slows down, birth contol pills slows it down too...
To move the valve down as the camshaft rotates.
Stop doing drugs and the swelling will go down!
I have a Stuart sea cock bronze with a nut that secures the on off valve spindle. This is fairly old fitted to me Sabre 27 built 1978. It is still in service and can be re-furbished if necessary.
Shut Down Valve- used in ON/OFF position only.
shut down non return valve
their difference is very simple. surface blowdown valve is for light impurities while bottom blowdown valve is for heavy impurities such as sludge, etc.