Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

[JANDREWB]

WHen and how do you clean cylinder crud?
I got a used 67 Johnson 6HP, 2 cyclinder, which I am cleaning up for first use on the water. Doing the usual- put in new impeller, plugs, points etc.. I noted as I looked on the threads, and inside the wall one of the plugs a certain amount of sandy black oily looking crud. As I looked through the spark plug hole, I noted the same crud was caked a bit on the cylinder head (not a lot but notable). The little I could see of the piston walls, they seemed fine. The fellow I got it from said it was running OK when he passed it along.
Before I test run it- Is that normal use build up or sign of some other problem? Will it clear up with proper ignition? Can it be cleaned without removing the head? (ie. some solution that burns it off ). Should the cylinder head be pulled and the area cleaned?
Thanks

 

[tashasdaddy]

Re: Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

you are looking at years of built up carbon, etc. doing a decarb will clean it up. while doing it you will think the motor is burning up, as it is going to smoke something fierce.

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

afterwards recheck compression.

 

[JB]

Re: Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

Sounds like a normal accumulation of carbon to me, JAndrew. It usually does not indicate a problem, though it can become one.

A thorough decarbonizing procedure should get rid of it without any teardown. Seafoam is a very popular product that, used as directed, does a good job. There are others that are similarly reliable.

Being an old salt, I feel obliged to tell about the old days. We used water to decarbon our engines back then. We dribbled or sprayed small amounts of water into the carb of our warmed up outboards, turning around 2000rpm. We kept this up until the black and grey smoke stopped and we only got some white steam in the exhaust. The interior of the cylinders were steam cleaned and pristine. We continued running the engines for about 5 minutes after we stopped the water so that it was all out of the engine before shutdown.

Seafoam probably does a better job and is a lot safer.

Be sure to use only 50:1 mixed fuel. Your predecessor might have been running 24:1, which would have accellerated the carbon buildup.

 

[F_R]

Re: Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

The crud is carbon, a by-product of combustion. Think of it in terms of ashes left over from a campfire. It really doesn't hurt anything on the piston tops and cylinder head unless it is loose and flaky, then the flakes get lodged in the spark plugs and cause mis-firing. However, the same stuff forms in the piston ring grooves and makes the rings stick, causing loss of compression and even ring breakage and cylinder damage. There are lots of "engine cleaners" or "carbon cleaners" on the market. Some give better results than others, I suppose. Frankly, I find all of them to be lacking in the really tough cases. But go ahead and try it. Can't hurt.

 

[JB]

Re: Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

Oh, Lordy! He did it again!! Fastest keyboard in the west.

Okay, Daddy, I am going to type with two fingers on each hand instead of one. That should even us up, huh?

 

[F_R]

Re: Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

JB, yeah I'm old and salty enough to know about the water trick, and yes it does steam clean the cylinders. However, after seeing what prolonged water intrusion does, I wouldn't risk it as a cleaner. Sure, there is a big difference between tempory cleaning and prolonged intrusion, but still......

BTW, last I heard, water injecting was the cure to get the (110hp?)air cooled Corvairs to run on unleaded. I had one that wouldn't even go downhill without pinging even with the timing set so far back that it wouldn't get out of it's own way. Of course it was the car that my teen ager daughter drove, so it's OK that it didn't have any power so I never did try the water injectors.

 

[JB]

Re: Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

I used water injection on my Corvair powered VW camper, F_R. It helped a lot.

 

[tashasdaddy]

Re: Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

well we jumped his thread, but i always wanted a Corvair. beat you by having the response in microsoft word document.

 

[dukboat]

Re: Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

Yep it works, we also use to put powdered bonami down the carb to get chrome rings to seat!

 

[JANDREWB]

Re: Johnson 6 HP 1967(CD-24)-Clean the Crud in Cylinder?

Thanks for the help- I have some very clear ideas from the many wise thinkers. Don't worry I will set aside the water idea for now and try the Seafoam. Ya'll can hop the thread all you want at this point- answer received. Thanks a million.