water pumping out new tell tale but head is extemly hot and motor is missing at WOT.

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littlelakeden

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May 2, 2010
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Hi everyone.I have a cooling issue.I wrote in before about my 1975 johnson 9.9 not puming water when you open up the throttle.I just put a tell tale in the top cylinder and it pumps the water out perfectly but it still dosen? come out the exhaust when you are at wide open throttle.The cylinder head is really hot.I can only touch the head or t stat cover for a couple seconds.The water coming out of the tell tale is fairly warm and when you are wide open the motor starts to miss until you back the throttle off.Is it possible that the thermostat is screwed.I just bought the motor a few weeks.Any info would be greatly appreciated.
 
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Daviet

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Re: water pumping out new tell tale but head is extemly hot and motor is missing at W

You could remove the thermostat and run it and see if it cools properly.
A defective head gasket can cause the problem you are describing, cools off at low speeds and heats up at high speed.
 
BonairII

BonairII

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Re: water pumping out new tell tale but head is extemly hot and motor is missing at W

littlelakeden said:
Is it possible that the thermostat is screwed.\
Click to expand...

Yup. I'm in favor of changing the t-stat on any new(to me) regardless of condition. They are cheap....and a bad one will ruin a motor in a hurry.
 
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littlelakeden

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Re: water pumping out new tell tale but head is extemly hot and motor is missing at W

I'm guessing that the motor is getting so hot that it's pre detinating which is causing the motor to miss.
 
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littlelakeden

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Re: water pumping out new tell tale but head is extemly hot and motor is missing at W

I will pull the t stat cover tomorrow and change it.Then I will take it for a drive and post the outcome.Thanks for the replies.
 
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Daviet

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Re: water pumping out new tell tale but head is extemly hot and motor is missing at W

You can run it without a thermostat installed to check it out and see if that is your problem.
 
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littlelakeden

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May 2, 2010
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Re: water pumping out new tell tale but head is extemly hot and motor is missing at W

O.k. so the new thermostat fixed the cooling issue but the motor still miss fires when at wide open throttle.When you back off the speed it will miss even more then run smooth at half throttle or less.Any ideas or did I buy a lemon.The motor runs great either than that.Starts good idles good.
 
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Outsider

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Re: water pumping out new tell tale but head is extemly hot and motor is missing at W

How did it run before you made design changes ... :confused:
 
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littlelakeden

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May 2, 2010
Messages
28
Re: water pumping out new tell tale but head is extemly hot and motor is missing at W

It didn't pump water well and it still missed at wot.I pulled the plugs today and the bottom one doesn't look the same as the top.I'm thinking the bottom plug is the one not firing all the time.i'm going to get new plugs and gap them and give them a try.If that doesn't fix it I am going to flip the coils and see if it's a bad coil.
 
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