compression check question

T

thefairlaneman

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What is the differance in checking the compression on a cold engine compared to a hot( warmed up) engine. My initial cold check shows 100lb in the top cylinder and only about 65lbs in the bottom one. I just installed a helicoil in the lower one. thanks
 
jbjennings

jbjennings

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Re: compression check question

From my short experience with a 2-stroke outboard, there shouldn't be much difference in compression when warm or cold, but either way, it's the cold compression that counts. If you have 100 on one and 65 on the other, you've got a problem. Taking off the exhaust covers and possibly the head to see what is wrong is probably next.
sorry,
JBJ
 
tashasdaddy

tashasdaddy

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Re: compression check question

agree. warm just gives you a more accurate reading of operation compression. either way you have a problem.
 
T

thefairlaneman

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Re: compression check question

Thanks. I need to make decision to take it apart or make a wall ornament out of it.gezzz . I think Im going to check out my other engine first. It ran well 15 years ago. (60 35 hp merc 300)
 
JB

JB

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Re: compression check question

Could it be that installing the helicoil caused your trouble? Did you remove the head to do the drilling, etc?

If not you might just get lucky and remove a bit of shavings from the rings.
 
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jwilkey84

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Re: compression check question

what kind of motor are you dealing with?
 
T

thefairlaneman

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Re: compression check question

My first check found a striped out lower plug. I installed the helicoil and carefully vacumed any metal shavings I could see. I didnt remove the head . The engine is a 61 40hp lark 3.
 
iwombat

iwombat

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Re: compression check question

You should always remove the head to install a heli-coil. Time to pop it off and see if you got metal shavings tucked in under the rings.
 
T

thefairlaneman

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Re: compression check question

Thanks for the advice. I plan to remove the head then and see what I can see. This engine I admit was a "pig in a poke" Its worth more time before I junk it but am begining to think I should have spent alot more money and got alot more engine....oh well.
 
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