1975 9.9 johnson bad head gasket?

matt88

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Some of you helped me with this thing last night and we came to the conclusion that I needed a carb rebuild kit. Well I was going to take the carb off this evening and take it to the shop in the morning but I decided to try the engine in a barrel first. The plugs kinda looked like they had some water on them so I retightened the head bolts. Now Im not sure if that fixed it or not but after tuning the low speed setting in a barrel the motor seems to run ok now. When I first tried to start it it died just like it has been doing on the lake. So I turned the low speed dial almost a full turn before it started running ok in the barrel. On the water hose it would run good at about 3/4 turn and now the low speed setting is at about 1 3/4 turn. My only complaint now is that the plugs are wet still. They were also wet when I was running it too lean?? I plan on taking the engine to the shop in the morning and letting someone more experienced take a look at it but I figured someone here could probably tell me the problem. Im thinking head gasket but Im starting to lose confidence in my 2 cycle diagnosing capabilities. I used to work in a ford dealership as a service tech and I work as a gas service tech now and I am pretty good with 4 cycle engines but I guess there is always more to learn,lol. Im just very thankful there is a place like iboats where us gear heads can help each other out. thanks in advance.
 

bktheking

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Re: 1975 9.9 johnson bad head gasket?

Did you check compression before and after?
 

kbait

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Re: 1975 9.9 johnson bad head gasket?

Water-wet plug(s) would indicate head gasket. And it sure wouldn't run on both cylinders no matter where you set the low speed setting..

Agree w/bk's compression test, as that'd show a faulty head gasket, or something more sinister...
 

bktheking

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Re: 1975 9.9 johnson bad head gasket?

I'm just going to start off every reply to a post with "did you check compression", I figure that it's a starting point with every motor problem but I guess it gets missed.
The won't idle in the lake thing points back to wrong adjustments on a carb or a dirty carb usually.
 

matt88

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Re: 1975 9.9 johnson bad head gasket?

I cant find my compression tester so no I have not checked compression. I guess I will have to find it or buy another one. Im just confused as to why I couldnt make this thing run right on the water because I tried to richen up the mixture then with no success. I guess I will have to see what the shop guy tells me in the morning. thanks
 

bktheking

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Re: 1975 9.9 johnson bad head gasket?

Wouldn't be the first time a loose head was a "got ya", guy on here same motor a couple of months ago had zero on his gauge, tightened er up and bam.
 

wilde1j

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Re: 1975 9.9 johnson bad head gasket?

You used a torque wrench on the head bolts, right?
 

matt88

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Re: 1975 9.9 johnson bad head gasket?

Well, I just about have it figured out now. Took it out today,ran ok no big issues except it still seems that it is a bit underpowered and topend was a bit rough. I took the carb off tonight to install the rebuild kit and found a big piece of the puzzle. When I replaced the water pump impeller a while back I lost the carb linkage so I made one out of a piece of coat hanger wire. I made it so it would turn the carb butterfly all the way to the metal stop tab. Well when I took it off to clean and install the rebuild kit tonight I was inspecting my coat hanger linkage and realized where I had screwed up. I had the linkage turning the butterfly past wot about 1/3 of a turn so that has thrown my timing way off. So I plan to shorten the linkage where it will stop at wot but I definitely plan to get the original omc linkage so I know its right. So 2 steps forward and three back.
 

matt88

Petty Officer 2nd Class
Joined
Mar 17, 2009
Messages
160
Re: 1975 9.9 johnson bad head gasket?

fixed the linkage,carb rebuild kit installed. difference:night and day. Its a different motor now. I appreciate the help and the advice,thanks.
 
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