Is This Motor Too Far Gone??

[gayle23]

I have a 1979 Johnson 6 hp outboard which I have owned for about 17 years. Prior to that it was owned by an outfitter and used for commercial uses so it has had a big life. Last fall I did a compression test and found both cylinders had compression of 50 psi. I decided to do a decarb to see if I could increase compression. I poured Seafoam into both cylinders and let it sit over night. In the morning I poured the rest of the Seafoam into about 2 gallons of gas, started the motor and took off. It smoked heavily for a short period of time, then things went well for about one city block. Then the motor started to get slower and slower, even with the throttle turned all the way up. The motor stalled twice before I got back to the dock. The motor barely runs.

I have also had trouble with the fuel pump. I rebuilt it and tested it to make sure it was operating properly (cannot blow into the outflow tube but can blow into the intake tube). Even though it seems the fuel pump should be working properly, I still need to pump the primer bulb periodically. I am thinking the compression is too low to efficiantly operate the fuel pump???

Also, the motor has been recently been jumping out of gear when running.

Anyway, I am seriously thinking of parting out this motor, even though I am very attached to it. A ring job, plus the lower unit problem seems like a lot to take on for a motor of this age.

Please advise.

Thanks.

 

[Bosunsmate]

Was it overheating?
If it went well for a block then the compression back then seems like it is adequate enough. You may benefit from changing the head gasket and giving the heads a little shave by rubbing them in a figure 8 pattern on some sandpaper covered glass.

THe biggest problem sounds like the jumping out of gear.
Hows the gearbox oil look?
Any metal shavings?

 

[gayle23]

I didn't find metal shavings in the gearbox, but then I have hardly run the motor since the lube was changed. I will pull the head to see what i can find. Thanks for your help.

 

[gayle23]

Well, I pulled the head. It doesn't appear that the head gasket was blown, BUT all the bolts were VERY LOOSE. I could not remove them with my fingers only, but it did not take much effort to loosen them with a wrench. I have owned this motor for about 17 years and have never removed the head so I guess the bolts worked themselves loose?? The inside of the hood has been getting more and more covered with an oily goop, which I didn't understand but I am now thinking this stuff has been blowing by the head gasket? Thanks for the idea regarding the gasket. This probably partially explains the low compression. I will now dismantle the lower unit to inspect the clutch dog. If I need a new clutch dog I will try to find a used one as it turns out they are quite expensive.

 

[racerone]

There is a wee hose that goes from bottom to top cylinder.--Often they are cracked and will spit fuel / oil all over the motor.

 

[gayle23]

I replaced the wee hose. I now believe the upper crankcase seal is leaking so I have purchased one along with a new head gasket, a used lower unit, and a new impeller. I won't be able to put it all together until some time next week. I am optomistic and will report back. Thanks.

 

[gayle23]

Well, I replaced the wee hose, the upper crankcase seal, the head gasket, and installed a "new" used lower unit along with a new impeller. The motor started on the first pull (kind of surprising). Everything was fine for about 5 minutes and then it started to lose power again, not as bad as last time, but loss of power nevertheless. I keep thinking this must be due to the decarb process as that is when this started. There are new fuel lines, but maybe some gunk came loose and is bouncing around in the high speed "chamber" under the aluminum disk??? Pressing the primer bulk does not help. Also, I did not install the bolts on the head all the way up to 60-80 psi as I could not believe the 1/4" bolts could withstand that pressure. They are much tighter than they were before, however, as tight as I could get them with a socket wrench. The extra leverage from the torque wrench felt like too much. It felt like I would twist bolts off. Any thoughts would be appreciated. SAThe cylinder walls looked great, no scratches or marks of any sort.

 

[racerone]

These head bolts have been torqued to 60 / 80 INCH LBS for some 50 years of production.-----Not sure what you are doing here ??-----Are you using a tork wrench that shows FOOT-LBS or inch-lbs on the scale.------1/4" bolts on your motor can be tightened to that specified torque !!!

 

[Intoodeeep]

Racerone is correct. My 235hp calls for 80-120 inch lbs if if I remember right. Torque pattern is important too. If you have a manual, check to see what it says. The sea foam probably knocked loose a bunch of crud in the carb. It sounds like you need to clean the carbs out real good. This sounds like a fuel problem. If your having to continue to prime the primer bulb, you may have a small leak allowing air to get in or even a bad primer bulb. The manual usually references how to check the fuel pump. Mine only calls for 5-7psi operating pressure for my pump.

 

[gayle23]

Thanks much. My torque wrench says "Foot-Pounds." There are two scales, one goes from 20 up to 140, and the other from 2 up to 20. I have been using the scale which goes from 20 to 140, and trying to torque up to 60 or so. Am I doing this right? If I am using the right scale I need to stop being such a wimp and do it right. I have been freaking out at about 40 and stopping there. Thanks.

 

[racerone]

At some point you need to determine what the scale says.----1 ft-lb is the same as 12 inch -lbs.---This should be simple.

 

[racerone]

Also 60 ft-lbs is equal to 720 inch lbs.

 

[gayle23]

Thanks. That really helps. I didn't connect with the foot-pounds vs. inch-pounds. It is good I didn't torque further as I was at 40 foot pounds or 480 inch pounds or so. I did do the torque pattern correctly. I will concentrate on the carb issue. I tested the fuel pump and it is working correctly. Pumping the primer bulb doesn't help the deceleration issue. Thanks much for your help.

 

[gayle23]

Well, I found a problem with the carb. The spring attached to the needle had come loose and was impaled on the top of the float.

 

[EZSteury]

Inch/lbs and FT/lbs are two very different scales, make sure it is inch/lbs or the equivalent in ft/lbs.

 

[EZSteury]

Inch/lbs and FT/lbs are two very different scales, make sure it is inch/lbs or the equivalent in FT/lbs.

 

[Tim Frank]

my OEM manual for 1976 6HP SPECS HEAD BOLT TORQUE AT 60-80 IN-Pounds

 

[gayle23]

Thanks for the clarification regarding inch pounds and foot pounds. I don't know how I missed it all this time. I fixed the carb, spring/needle problem. The motor now starts on the first pull and goes really fast (unlike before the decarb). However, once in a while it wants to die. If I then move the throttle up slightly it roars, and then slows down to normal. Sometimes it just dies and stops. If it stops I can restart it right away. I don't know what to think of the racing/dieing problem. It must be fuel-related, but I can't figure out what is causing it. Thanks.

 

[Mikus11]

When it starts to die, pump the fuel primer bulb on your gas line. If the motor comes back strong, you've probably got a weak fuel pump. Easy to rebuild.

 

[gayle23]

Well, to report the results of my efforts. I replaced the upper crankcse seal, the small recirculating hose, and the cylinder head gasket. I found the problem with the carb (loose and wandering needle spring). I completed the decarb process and installed new plugs as well as a good used lower unit with a new impeller. This motor starts on the first pull, idles nicely and accelerates with real gusto. Thanks for your help....a complete success.