Yamaha 2001 4 stoke cooling

[Desert Owl]

I have a 2001 Yamaha 4 stroke 80 HP carborated engine. less than 200 hours on it.
Entire engine gone through , new impeller, thermastat , carb kits. Zincs were all good. Heres my question.

Engine runs awesome and a solid stream of water flowing from engine however after engine has been running for awhile the stream of water for the cooling slows to a trickle......is this normal? Engine has not over heated or emergency alarms or shut off have happened as i understand this engine has that protection system on it to protect from over heating. When I bought engine it was run in salt water 1 -2 months every year for a totlat of 5 years and i thought salt deposits were dropping off inside and clogging the outflow discharge line after it warmed up which did happen however it has run long enough and I openend up the outflow line and made it bigger.
Its almost like the engine is acting like it has a thermostat that works like one in your car. Is this the case with this engine and is what Im experiencing normal? I like to see a constant solid stream of water flowing from my engine.
Any advice input and help is greatly appreciated..

[99yam40]

My guess is you are speaking about the tell tail water stream not the cooling water flow itself otherwise it would over heat if the was little or no flow. Thermostats will open when motor warms up and allow water flow to keep motor at the proper temp, but will not affect the tell tail flow.
Tell tail is just an indicator that your water pump is functioning and should stay strong at all times.
You may have stuff breaking loose from inside motor and plugging up the flow, try running a thick piece of mono or weed wacker line up it while motor is running and the flow has slowed to see if that will help. Blowing compressed air to clear it may help also.

If that does not help then you may need to replace the water pump housing along with the impeller kit