My 89 Yamaha 200 overheat warning comes on when the engine idles for several minutes. I recently changed the waterpump with a new kit and the problem persisted afterreassembly. I have tell tale stream. The local Marina mentioned that the "pop-off valve' might not be functioning properly. Can anyone tell me where this is located and how tocheck it?
One very simple check (I have a Yam 150) is to simple see if it peeing real strong...I ocasionally have to pull the little black hose off the tip of the nozzle that snaps into the cover and clean out the little plastic holder. If you ran in shallow water you may have picked up some small trash there. If you find something in it..take note of the improved pressure and remember it.steve
The valve you are referring to is located at the base of the engine block. You will see a 1" hose coming around the block which attaches to what looks like a t-stat housing on an auto engine. Remove the screws (but be careful that you don't snap them off) and you will find a plastic 'plug' and a spring. This is what they are refering to. I believe it is called a 'Poppet valve' or bypass valve. Even if you have the telltale stream, the poppet valve might not be open all the way causing a lack of water flow and eventually an overheat. I am speaking from experience on this one. These things usually get seaweed and other junk in there that needs to be cleaned out. And sometimes they just get stuck in one position and need to be reseated.
Yamaha 200 overheats when idling
engine idles for several minutes. I recently changed the 
Linear Mode
