For 12footer and anybody else

[Artjo]

You were right. I have no compression in my number 4 cyl. here were the readings:<br /><br />#1 - 79<br /><br />#2 - 75<br /><br />#3 - 80<br /><br />#4 - 22<br /><br />My neihbor told me to put some marvins mystery oil in the gas and squit some in each cylinder,to see if that could free a stuck ring. <br /><br />Can you tell me what I will need done now that I have found the problem. Thanks.

 

[JB]

Re: For 12footer and anybody else

Your compression is bad on all cylinders, just worse on #4. What kind and age engine are we talking about??? When you abandoned your original posting you threw away everything you had told us before.<br /><br />Red sky. . . . <br />JB

 

[fone_man]

Re: For 12footer and anybody else

Here you go... JB<br /><br />"I just purchased a 1966 Starcraft w/ a 66 Merc 650, 65 hp, 4 cyl. I am having problems. I would like to ask you a few questions. My email is Artjo23@yahoo.com<br />Thanks"<br /><br />fone_man

 

[fone_man]

Re: For 12footer and anybody else

JB... forgot<br /><br />posted 7/6<br /><br />go to search & put in ARTJO... will find it for you<br /><br />fone_man

 

[12Footer]

Re: For 12footer and anybody else

Artjo, the Marvel Mystery Oil (note name)<br /> trick is a good old tried and true method of desolving some of the carbon from the ring lands (which is what he was talking about).<br />Another method on a running engine,is to use 2cycle decarb cleaner spray. A good 3 second shot of this stuff into each cylinder,let it sit overnight,and turn over the engine without plugs. Then,run another compression test.<br />There is a slim chance you'll regain lost compression.<br />More likely tho, it is time for a rebuild.<br />Depending of course,upon how much compession you recover.<br /><br />Give it a shot, and I'll keep me fingers crossed till I hear from you.

 

[Dunk]

Re: For 12footer and anybody else

That horse is wipped. Those old 60's Merc had near 150lbs of compression when they were new. <br /><br />12 footer is right about a carbon cleaner. Try to find some Seafoam at a NAPA or a CarQuest and soak the pistons well. The thing is carbon cleaners work by soaking into and softening the carbon so it will burn out. You'll need to get her running and warmed up for the stuff to work right.<br /><br /> Somehow I doubt you'll bring her back to live with a can of anything, but it can't hurt to try.

 

[Artjo]

Re: For 12footer and anybody else

Still no change in compression. Thanks for everyones help. I think it is time for a rebuild. What is involved in this and most importantly, does anybody know how much it will cost. Just a rough estimate unless there are some mechanics out there who can give me a more accurate estimate. Thanks again.

 

[wa3ipb]

Re: For 12footer and anybody else

Check the head gaskets! We just replaced one yesterday in our 4 cyl 1977, 85 Hp Johnson that was showing low compression in one cyl. That was the problem! It was worn with a dime size hole in it. Compression is back!

 

[Artjo]

Re: For 12footer and anybody else

I wish I could but I dont know where the head gasket is. Very new to boating, and dont know my way around an outboard engine very well. Can you be more specific. Is it a difficult job to do. I would like to repair the problem myself if possible. Thanks.

 

[JB]

Re: For 12footer and anybody else

Yo, Art. The head gasket is between the cylinder head, where the spark plugs screw in, and the rest of the engine. Remove all of the bolts that hold the head on and nudge it off.<br /><br />The gasket may stick to the head, or it may stick to the main engine block. Look for any evidence that pressure could get out of a cylinder past this gasket. While you are there let us know how much carbon buildup you see on the piston tops and in the cylinder head. That could decide what we recommend next.<br /><br />Red sky. . . .<br />JB

 

[wa3ipb]

Re: For 12footer and anybody else

Thank you J.B.! Art, I would highly recommend you get a shop manual for your engine/year. Many photo's and repair "How to's) in it. Good Luck!

 

[hondon]

Re: For 12footer and anybody else

This engine does'nt have a cylinder head.

 

[JB]

Re: For 12footer and anybody else

Hahaha! Thanks, Hondon. Sometimes we get so buried in generic troubleshooting, we forget about particulars of the engine we are talking about.<br /><br />Red sky....<br />JB

 

[Artjo]

Re: For 12footer and anybody else

Okay.......I removed the cylinder cover that the plugs screw into. The gasket looks good. There are no holes or tears in it. if it looks good can I still use it. I know it is best to just replace it, but for the time being can I use it. Next question is about the bolts that I removed. A few of them broke when I was removing them. I went to lowes to find replacements. The threads on the new bolts are spread firther apart. Should I still be able to use them to put the gasket and plate back on, and most importantly what torque value do I use to tighten them. Thanks to everyone.

 

[seaman]

Re: For 12footer and anybody else

dont reuse a head gasket and the bolts you get to replace the old ones should be exact fits thread size length of bolt etc. It sounds like you need someone around you with knowledge of engines especially marine motors . I would also invest in a manual for more reassurance

 

[Artjo]

Re: For 12footer and anybody else

I did purchase a SELOC manual for my engine, but it covers so many models that it doesnt help me one **** bit. You have to be a G D marine engine expert to understand what they are talking about. I admit my knowledge of engines, especially marine engines is next to nothing. Unfortunetly there isn't anybody around me with that knowledge, seaman. Therefore I must rely on this board and the kindness of others who pocess this knowledge to help me. I will get the new gasket and the correct bolts so I can get this thing back together. Then I will try to find a marine shop that isnt three weeks backed up to rip it apart for me. Thanks to everyone who has helped.