johnson metal shavings in plugs

[Joe Fisherman]

I have a 77 65hp johnsons. I was at crusing speed today when my motor cut off at open throttle. After starting it back up again I noticed gas vapor spitting out of the bottom carb cylinder. After getting towed to dock I cleaned my plugs off and It ran better but still a little gas vapor out of bottom cyl.When i got home and pulled the plugs out again I noticed a little metal shavings in the plugs. With brand new plugs it idles fine and sounds a lot better but is there something wrong in my motor. will dirty plugs cause you to cut off at almost full throttle

 

[sparkroost]

Re: johnson metal shavings in plugs

Sounds like you sucked in a reed. Probally won't reach full RPM anymore... until you fix the reed, if broken. Shavings are not good.. hopefully you still have a good cylinder.....but doubtfull if you have found shavings.

 

[Duck Loads]

Re: johnson metal shavings in plugs

Yep, What sparkroost said.<br /><br />Good luck

 

[Joe Fisherman]

Re: johnson metal shavings in plugs

When you say reed what is that a small screw?

 

[sparkroost]

Re: johnson metal shavings in plugs

A reed is a 1 way valve that is after the carb. When the piston comes back down it makes pressure. That pressure puts force on the reed, closing it off to the carbs. A reed is a few flat metal pieces that rest on a "cage". The metal or reed is only allowed to move in one direction. The reason you see fuel spitting out the carbs is because there is nothing to block off the pressure coming from the piston from it's down motion.

 

[DJ]

Re: johnson metal shavings in plugs

Joe,<br /><br />The reed block is behind the intake manifold. The intake is what the carbs. are bolted to.<br /><br />Because of the age of the engine, I would remove the cylinder head and have a good look at your cylinder bores. You may be lucky.

 

[Joe Fisherman]

Re: johnson metal shavings in plugs

I wonder if it was doing this since I bought the boat and the plugs just fouled out to badly today. It always seemed to burn to much gas. What will happen if I keep running the motor like this. I dont work on boats much is it worth payinig somebody to fix and how much do replacement reeds cost?

 

[DJ]

Re: johnson metal shavings in plugs

Joe,<br /><br />If you keep running it with something metallic letting go inside, it will eventually stop completely and be CATASTROPHIC.<br /><br />As mentioned, I would pull the head. That's easy and it will give you real insight as to the general health of the engine.<br /><br />It can be done for about two hours labor and $50.00 in parts-if you decide to reassemble.

 

[ob1jeeper]

Re: johnson metal shavings in plugs

Just got done going through an almost identical issue with a Johnson 235... My guess is that it will require a total re-build, as the reed amterial is hard enough to score the cyl walls and for sure damage the piston (not to mention what it will do to the bearings & crank if you keep running it), but you won't know that until you get the heads off to see what kind of damage the cyl walls have, etc...<br /><br />As for whether it's worth a re-build, that would have to be your call... Take it to a reliable local shop, and get an inspection and estimate for repairing what's wrong... Then decide how much it is or is not worth to you...<br /><br />Good Luck... Obiwan

 

[sparkroost]

Re: johnson metal shavings in plugs

I doubt very seriously that you would reach full RPM with a broken reed.<br /><br />Your post described it all.. Running fast, motor stopped, shavings on plug, spitting gas. If you are lucky the shavings you are seeing is the metal reed after having been smashed by the piston into little pieces. Here's a test for ya.. Get some of those shavings and put a magnet to them... do they stick to the magnet? If they do, it's metal. If not aluminum. Metal can be from the cylinder wall, crankshaft, bearings or the metal reed. aluminum is from the piston. Both are bad news, but I would think aluminum would be better. This indicates the piston or head. Not the greatist, but better than metal.<br /><br />As DJ and other have said.. you are at the beginning of your problems.... run it more and you will kill it good.<br /><br />For now(since you have already ran it after the fact) get a compression gauge and check that cylinder against the others. If you are within 10%, remove the head, clean, re-assemble and pray you didn't pass shavings into the lower end. Just a few shavings can kill the whole motor. So... if you cannot afford repair costs, or have the means to do it yourself....you are pretty much stuck into buying a good used motor or take up a new hobby

 

[OBJ]

Re: johnson metal shavings in plugs

Joe, if nothing else, take a compression test of the cylinders. They should be within 10% of each other. The reeds, as suggested by the previous posts, behind the lower carb is damaged. Not only will you be taking a chance of getting totally stranded on the water if you continue to use the engine like this, you will be rishing the possibility of a gas vapor explosion from the vapors spitting out the lower carb.<br />Pull the head as djohns suggested. There is nothing magical about it and no voodoo is involved. The engine you have is a great running engine when tuned correctly and is mechanically sound.<br />A good service manual can guide you through the diagnostic process. Generic service manuals will help also but if you get into a rebuild, an OEM service manual for your engine is the only way to go. Reproductions of the original service manual can be had through Ken Cook Comp.<br /><br />Good Luck!!

 

[Joe Fisherman]

Re: johnson metal shavings in plugs

I did a compression test on the motor and the top two cyl are 125psi and the bottom one is 120psi. With that good of compression do you think I can get away with just replacing the reed valve without pulling the head off. thanks for suggestions!!!!

 

[Chinewalker]

Re: johnson metal shavings in plugs

That depends - do you want to risk it that you really do have ALL of the metal shavings out? Unless you want to have a bearing go or score a bore, tear it down and do it right. All it takes is one piece of steel reed, stuck to the crankcase wall at the moment, to slip down and chew up a bearing, piston, etc.<br />- Scott