Power head torque

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ed72vette

Seaman
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Oct 21, 2004
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I am ready to get my 2004 90 hp Yamaha ready for the water. This motor has 50 hrs of running time, so I thought I would check the power head torque. I have the Yamaha manual and it says to torque the 10mm powerhead bolts to 22 lb/ft. That seems high for such a small bolt. Am I missing something or is this correct?<br />Ed
 
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rodbolt

Supreme Mariner
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Sep 1, 2003
Messages
20,066
Re: Power head torque

exactly what bolts are ya trying to torque? by 10mm it refers to the bolt diameter not the bolt he4ad size. if you try to get 22ftlbs on a 10mm headed bolt it will snap off. standard bolt size for a 10mm head is 6mm, standard hex size on a 10mm bolt is 14mm.standaerd hex size for 8mm bolt is 12mm. were I you I would purchase a factory manual. while it wont explain much the pretty pictures usually list torque specs. do you know he procedure for correctly retorquing a bolt? the cyl head, not powerhead, retorque is a 200 hour OR annual check.whole lot more under the ANNUAL check as well.
 
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ed72vette

Seaman
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Messages
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Re: Power head torque

Rodbolt,<br />Thank you for the quick response. I am on page 5-19 of the 60-90c yamaha manual. It shows you the full cylinder with the bolt tighting sequence. In the text to the right of the pictures it tells you 2 stepts to tighten the head. It does not indicated the bolt sizes, but the small bolts on the top have a head size of 10mm. The manual does not differenciate the sizes but tells you the final torque for all the head sizes are 22 lb/ft. Hope this explains it better.<br />Ed
 
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rodbolt

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20,066
Re: Power head torque

it does but its difficult to follow. the headbolts are all larger than the waterjacket cover bolts. some 3 cyl motors did not have them. some had 3 10mm hex bolts down the center. trust me. if you attempt to torque the 10mm hex bolts to 22ftlbs you will snap them off.<br /> check very carefully at the interpetation of your manual. I think the 4 small bolts your refering to are the t-stat housing bolts. they WONT take 22ftlbs.
 
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ed72vette

Seaman
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Oct 21, 2004
Messages
71
Re: Power head torque

Rodbolt,<br />The manual is very confusing. I have seen better written manuals. It just seemed to much torque for a small head.<br />You are up early on a Sunday morning. I really appreciate you talent and expert advice. <br />I have not worked on outboards,but have alot of automotive and inboard experience. This is a different animal. Thanks again.<br />Ed
 
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rodbolt

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20,066
Re: Power head torque

no worries. if its a yam manual I will agree. if you think yam manuals suck try a nissan or tohatsu :) <br />always a bright side :)
 
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