Optimax 115 Cooling Problem-Any Advice?

[reccrew]

I have a 2008 Mercury Optimax 115 with a near new impeller changed this spring(reputable dealer) and it has less than four hours on it. On my last two trips within minutes of shutting down from 4500-Max RPM to idle at 750 RPM the engine begins to overheat and a warning signal activates. She won't do it at 1500 RPM or above, just at near idle. The water discharge is light at lower RPMs, I cleaned it from the discharge hole back a few inches without improvement. I'd appreciate any advice that you may offer; she's still under warranty!
Thanks!

 

[hkeiner]

Re: Optimax 115 Cooling Problem-Any Advice?

If the motor is still under warranty, the obvious answer is to take it in for warranty repair if the cooling is failing. If you are interested in what the many possible causes may be for cooling problems, the below linked guide will give you some ideas. Having a water pressure guage on the motor would make the guide even more helpful.

http://forums.iboats.com/attachment.php?attachmentid=26806&d=1240515681

 

[starcraft1982]

Re: Optimax 115 Cooling Problem-Any Advice?

+1 on taking to the dealer for repair.Dont dig in yourself and give them a reason to void your warranty(they want to nowadays!)as for another point to your post.What does youre manual recommend for max WOT?4500 seems low to me(but i have no experience w/newer motors,only the "old faithfuls").i would guess youre running @700-1000rpms too low.An engine check and(if check turns ok)a new prop might be in order.JMO

 

[reccrew]

Re: Optimax 115 Cooling Problem-Any Advice?

Thanks I appreciate the advice from all: I have contacted the dealer who says, it may well be the thermostat or poppit valve. The 4500 to WOT may have been confusing as I was referring to the RPMs I was running for a sustained time. My WOT is at/near 5500 with it's current prop.