'62 Evinrude 10 running hot

samo_ott

samo_ott

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So, I've changed the impeller in it. When running at WOT the exhaust is a normal temp on my hand but when I stop and pull the hood and splash a few drops on the head they sizzle off pretty quick. And it seems to hot to the touch. I know some of my other 10's seem to run hottish also and have heard the 9.5's do but I'm not sure what else to check. As the exhaust seems fine the only thing I can think of is a thermostat restriction? Or maybe I should pull the head to see if there's any issues in the water jacket? Any other ideas?
 
samo_ott

samo_ott

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Re: '62 Evinrude 10 running hot

Dang... no replies... another thing I forgot to mention was that the exhaust housing cover was also at normal temperature... so it's only the head...
 
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F_R

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Re: '62 Evinrude 10 running hot

There are two water flow routes through that powerhead. The thermostat determines which way the water flows. When it is closed, water goes one route and when it opens the 'stat poppet goes up against the hole in the cover plate, blocking it off and causes the water to go the other route.

I'll bet you have some restriction in the cooling passages somewhere.
 
samo_ott

samo_ott

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Re: '62 Evinrude 10 running hot

What are the 2 routes? Where does each go? Would a stuck thermostat stop water from going to the head? I've never had a failed stat before but do have a new one from an 18 that I think is the same.
 
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F_R

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Re: '62 Evinrude 10 running hot

Well Samo, since it's been 40 years since I sat down with a stripped powerhead and studied the circulation patterns, I can't answer for sure what is involved with each circuit. One thing is for sure, the exhaust cover is always cooled because that would get blazing hot in no time without cooling. I do remember the poppet closing off one passage when open because that is unique to the 10hp.
 
samo_ott

samo_ott

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Re: '62 Evinrude 10 running hot

Only 40 years and you've forgotten already? Sigh! :)

Well it would make sense then to have the exhaust housing always cooled and the head thermostatically controlled for proper combustion temp. At least it makes sense to me :) So a faulty 'stat could do it then.

So, I'll pull the 'stat tomorrow and see what I see and if I have to then I'll pull the head. (but I hope not to)
 
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