Overheating?, Thermostat?

[Trophyboy]

Hi Guys, I could use a little help. I have a 2002 135 Optimax. It has 350 hours on it, had an intermittent overheat alarm at the end of last year traced to a faulty temp sensor replaced when the annual servicing was done. Now I'm getting the overheat alarm at 4400-4500 RPM's only. I back off a little it stops. Does this sound like the thermostat is not opening all the way or enough at just that rpm or? Anyone have any ideas whats going on? The motor seems a little new to have the thermostat malfunctioning. The impellor etc was replaced as part of the $650 annual maintenance. Sure appreciate any help. Thanks

 

[outboardguy]

Re: Overheating?, Thermostat?

Are you sure that it is the overheat alarm that you are hearing?Is there any way you can check the tattle tale when it is overheating?The reason I ask this is, the optimax's use the tattle tale water flow to cool down the fuel rail and then the air compressor and then exit the engine.Not at all like the traditional outboard.If in fact the air compressor is what is setting the alarm off, you should remove the upper cowling, then unbolt the two side cowlings and pull back the port side. Toward the rear of the motor you will see the hose attached to a spigot going through the fuel rail.Now cut the zip tie and remove the hose, next unscrew the spigot and you will see all the lakeweed covering the screen on the spigot.Clean the spigot and reassemble and retest for overheating.

 

[Trophyboy]

Re: Overheating?, Thermostat?

Thanks for the reply...sure appreciate the help. It is a steady alarm I'm assuming is the overheat. I can evaluate the telltale as I pick up rpm's. Should it look/feel different as it alarms/overheats? Am I going to be able to tell if the blockage is at the area you suggest? Thanks

 

[quantumleap]

Re: Overheating?, Thermostat?

Just out of curiosity, what exactly does the annual maintenance include for $650?

 

[Trophyboy]

Re: Overheating?, Thermostat?

Supposedly...waterpump kit etc, lower end oil,sparkplugs and an overall check-up of cables etc. They say five hours of labor. This is the California Bay Area but it still seems like a rip to me too. I'll get a manual and do most of it myself next year. I don't think they even time/tune anything on that motor other than pressure check the air /fuel. Am I wrong? Thanks.

 

[quantumleap]

Re: Overheating?, Thermostat?

That's what I thought. If you are mechanically inclined you can do the waterpump yourself with a manual. The rest of the winterization procedures can be found on this site. In all, you'll save yourself about $500 bucks. If you have any problems with the work next time, just ask the guys here for help.

 

[schaiss]

Re: Overheating?, Thermostat?

Your annual maintenance check will NOT include a full tune up !! For starters, pull the T-stats on your engine and CLEAN them. Until you have actually seen the thermostats on one of these outboards, you will never believe how fouled they get. I own a Merc 150 Hp V-6, and I pull the t-stats at the end of each season (YUCK!!). The t-stats on my engine are set to be open at 140 degrees, when my tell tale is flowing!