Merc 170 engine shuts down at 180 degrees

R

rrdbllc

Recruit
Joined
May 13, 2011
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1
87 Searay Merc 4 cy 170 engine/Sterndrive shuts down when it reaches 180 degrees. Any ideas why?:confused:
 
badbowtie

badbowtie

Chief Petty Officer
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May 18, 2007
Messages
634
Re: Merc 170 engine shuts down at 180 degrees

I would guess there is some kind of kill switch like the temp buzzers hooked up that kills it when it reaches that high. I would start buy figuring out why it is getting up to 180 seems hot to me.
 
F

firstboatbuild

Seaman Apprentice
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Apr 25, 2011
Messages
38
Re: Merc 170 engine shuts down at 180 degrees

Are the thermostats opening all the way? Also is the sending unit working correctly? If it is not the temps may be incorrect. I would agree with badbowtie that does seem hot to be running that hot. I'm thinking it should stay 160- 165 check the water pump, thermostats make sure full water is moving through the motor.
 
S

stonyloam

Vice Admiral
Joined
Mar 13, 2009
Messages
5,830
Re: Merc 170 engine shuts down at 180 degrees

Normal operating temperature for a 470 is 165-200 F, so you are well within the correct range. The thermostat is a 160, and opens at ~160 and is fully open at ~180. There is no (stock) thermal cutout that I know of. I suspect that you may have some electrical or fuel issues when it gets warm. Maybe coil or grounding issue. Good luck
 
solar7647

solar7647

Lieutenant Junior Grade
Joined
Apr 23, 2009
Messages
1,218
Re: Merc 170 engine shuts down at 180 degrees

Sounds like an after market temp sensor was installed to prevent over heat, if that engine over heats you got all kinds of problem they will blow head gasket quick when they do. So your lucky, you need to figure out why it's getting hot. Pull thermostat and test it. Heat up some water and throw a thermometer in it. The thermostat shoult start to open at 155-162 and be full open at 180 if it dosnt, change and try again. If it test fine I would check the pump in the drive. Also inspect for any leaking.
 
nola mike

nola mike

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Apr 22, 2009
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5,881
Re: Merc 170 engine shuts down at 180 degrees

check your temp is accurate first. my gauge reads 140 when the actual temp is ~175.
 
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