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No Compression 200hp Johnson 1989

T

tom

Regular Contributor
I have a 200hp 1989 Johnson t

I have a 200hp 1989 Johnson that was rebuilt by Fast Eddy's Outboard Motor and Lawn Care Service.
(I know but he was cheap). The engine ran for about 10 to 20 minutes and then ran like hell. I called Fast Eddy and he came and looked at the engine and claimed he fixed it. He told me one of the cylinders was "stuffed". It now ran but not that great.
I then took it to God's Outboard Motor service and they told me that one off the cylinders has no compression. I don't know what Eddy did but since he has now been shot I was wondering what to do. I want to do the repair myself this time (I have average mechanical skill) but I am unsure as to a) buy a rebult powerhead b) repair this powerhead or c) jump off the seawall.
Thanks for any advice.
Tom
 
"Powerheads do not blow (f

"Powerheads do not blow (fail) by themselves, something cause it to fail.... clogged carburetors, faulty ignition, something of that nature.

The original cause of the failure would need to be corrected. Failure to do so would result in a repeat of the powerhead problem.

I strongly suggest that you purchase a OMC service manual for that engine (be sure to list the engine model number) at:

http://www.marineengine.com/manuals/johnson/

Study the manual thoroughly before attempting to rebuild your engine. Good luck.

Joe (30+ Years With OMC)"
 
" Thanks Joe. Yes, I have alr

" Thanks Joe. Yes, I have already purchased the shop and parts manuals from the source you mentioned a few days ago. I am also the guy that had to replace the magnets on the flywheel since one was broken and they were all on one side. Could this be a possible source of the bad cylinder? I quess I will still need to remove the powerhead and disassemble to see if their is other problems? Maybe try running it again to see what compression I get now? Punt?

Thanks,
Tom "
 
"Tom..... Remove the s/plugs,

"Tom..... Remove the s/plugs, then rig up a spark tester whereas you can set a 7/16" gap. At a cranking speed (300 rpm or higher), the spark should jump that gap on all cylinders with a strong blue lightning like flame.... a real strong wide snap!

The stator under the flywheel has small coils within it which pertain to the battery charging system. However, that stator is a two fold purpose item, the other of which is the power supply (the beginning) of the ignition system.

Examine that stator closely for cracks, oozing of a substance, etc, especially if it is a 35 amp charging model.. If you see any cracks or oozing, that would indicate that the stator is failing which would result in a voltage drop to the powerpack(s), which in turn would result in erratic, faulty ignition.

Erratic or faulty ignition would result in what most mechanics refer to as a "washout"... the s/plug isn't firing, incoming gasoline builds up and eventually overcomes the oil/fuel mixture which results in a lack of lubrication to that particular cylinder.... and tears the piston and cylinder wall up.

Even if you have, or seem to have excellent spark, check that stator closely anyway.

On any powerhead rebuild project, thorough cleaning and rebuilding of the carburetors is a must. If even one carburetor jet is fouled, especially if it's a high speed jet, the engine will run lean, resulting in improper lubrication to the pistons, bearings etc.

Running the engine any further is not a good idea. The engine may be on the verge of throwing a rod at the moment and you really don't want to go that route. Simply take another compression check, jot down the readings pertaining to the particular cylinders, then remove the cylinder heads to make a visual inspection.

Joe (30+ Years With OMC)"
 
" Thanks Joe... The stator wa

" Thanks Joe... The stator was replaced when the powerhead was rebuilt (about 25 hours or so ago). I have already visually checked it and it appears to be okay. I will check it again.

Also, I will check the spark and carbs. Can you recommend a good place to buy the rebuild carb kits and other Johnson motor parts?

Thanks again Joe for pointing me down the right path. This should keep me busy for awhile and I will let you know what I find.

Tom "
 
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