1992 50hp mariner overheating at idle

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bitterroot

Cadet
Joined
Mar 27, 2011
Messages
6
I have a 1992 50hp Mariner outboard and while at a idle and trolling the overheating alarm keeps going off. I kick into neutral and give it some gas it goes off after a few seconds. There is plenty of water coming out of the pee hole at all times. Could this be the poppet valve? If so where is it on this particular motor?
 
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joed

Lieutenant Junior Grade
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Sep 28, 2002
Messages
1,132
Re: 1992 50hp mariner overheating at idle

Change the impeller. I had the exact same problem on my 94 60 hp. The vanes are bent and stiff. They pump water but not enough at low speed. Water was constantly coming out the P hole the whole time.
 
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bitterroot

Cadet
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Mar 27, 2011
Messages
6
Re: 1992 50hp mariner overheating at idle

Thanks joed, I will try that. What exactly is a poppet valve and does this particular motor have one?
 
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bitterroot

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Joined
Mar 27, 2011
Messages
6
Re: 1992 50hp mariner overheating at idle

Ok another stuoid question where exactly is the impeller? I thought when I took the lower unit off it would be right there but I guess not. Do you need to take the cover off around the drive shaft into the top of the unit?
 
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carholme

Rear Admiral
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Sep 4, 2010
Messages
4,845
Re: 1992 50hp mariner overheating at idle

root;

Here is the parts list for your engine:

http://www.crowleymarine.com/mercury-outboard/571.cfm

Under GEAR HOUSING (DRIVE SHAFT), see item 25 (impeller) covered by item 27 which should be staring you in the face with the lower unit removed, seen here:

http://www.crowleymarine.com/mercury-outboard/parts/571_260.cfm

Under CYLINDER BLOCK AND CRANKCASE. item 23 is the poppet valve, seen here:

http://www.crowleymarine.com/mercury-outboard/parts/571_150.cfm

Gerry
 
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