King Marine - how hot to spin prop
King Marine, on another thread you stated that running hot could spin a prop. Last year I had 2 props spin on the same day at different times with no apparent reason. I also noticed that my temps would come up when trolling or at low speeds going thru back waterways.I don't know how hot is too hot.The pee stream was too hot to hold my hand under for more than 10 sec I guess. Maybe 160 degree. The engines a 96 merc 200 EFIs. Thanks for any help. Dan
Hi Dan, Your engine should operate at approx 143 degrees. I would recommend servicing the water pump, thermostats and poppet valve Assembly if you have not done so in the last three years. A lot of people service the water pump but always seem to over look the thermostats and poppet valve.
One other thing that can spin hubs, is using the wrong trim tab on the cavitation plate. Some Yamaha and OMC (BRP) product utilize a water pick up on the trim tab that dumps water back into the exhaust to help cool the gearcase and propeller hub. Mercury does not use this system.
Thanks for the reply.This would be my 3rd year on poppets and pump,2nd on thermostats.I was thinking poppets from what I've read. I believe overheating at low speeds is a symptom.I'll check the manual and maybe give it a try.Thanks again Dan
Originally Posted by njdan
The popet opens around 2000rpms to let water free flow thru the engine. If you are getting hot at idle rpms it's either the tstats or the water pump. I recommend you only use Merc water pump parts.
i 2nd dunk, i had this problem last year, i used an off brand water pump kit, and even with new t-stats and new poppets she still ran hot. this year i got the genuine stuff from king marine, and she pumps water twice as good as last year.you would be surprised what t-stats look like after just 1 season. now you can put your face on the motor after running 20 minutes and not get burned.and now the water out of tell-tail isnt even hot enough to make hot chocolate
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