1989 Mariner 150hp thermostat

"I have 3 different manuals fo

"I have 3 different manuals for my 2 1989 Mariner 150hp engines and they all show picture of thermostat, but none show where it actually is on the v6 engine. I want to replace them. Please help."

"The thermos are in the cylind

"The thermos are in the cylinder heads at the top and while your at it replace the poppet valve as well its on the stb side down low, you really need a manual it would make it easier for you to work on."

New member looking for help with Thermostat replacement on 2005 Optimax 150. One screw for the thermostat cover is directly under the air preasure hose connection to the fuel rail. The question is,

should I remove screw from the holddown clamp that holds the hose connection [several parts come loose and new o-rings needed?] or

disconnect the hose from the connector [one of those stainless steel crip clamps -what is the best way to remove/open- around the hose] and hope I don't damage the hose in the process and install a screw type hose clamp.

Any help is greatly appreciated.