1988 Johnson 200 Compression

[roadracer4U]

I'm looking at a boat with a 1988 Johnson 200 outboard. The compression on all six cylinders is between 60 and 62 psi. The boat has been stored inside for two years, started right up, and sounded good while running. I'm just concerned that the compression should be higher, around 100 psi, yet think since they're all VERY close to each other, pehaps this is ok. Anyone have any suggestions? Do you think this is a good engine or old and tired? Thanks for any help you may have!

 

[jfm1]

Re: 1988 Johnson 200 Compression

should be 100 plus try a different gauge 60's way to low could be compression gauge is no good

 

[ob15]

Re: 1988 Johnson 200 Compression

Did you check the compression before or after you ran it? If after, something is wrong or gauge is no good.

 

[roadracer4U]

Re: 1988 Johnson 200 Compression

I checked the compression before running the boat. I rechecked it again with a different compression tester, registered 75-80 psi. Is this engine trashed or do I need to run the engine up to operating temperature first?<br /><br />Thanks for the help!

 

[jfm1]

Re: 1988 Johnson 200 Compression

ok buy a can of seafoam and do a decarb follow the directions and redo the compression test I don't think your motor is trash gained 20 psi I think its just a gauge thing but do the the decarb

 

[CFronzek]

Re: 1988 Johnson 200 Compression

Even at 80 lb. all the cylinders are on the downward slope. Buying an expensive boat with a motor that "may" improve a bit with a decarb is kind of risky. Are you willing to finance a rebuild if the seafoam trick doesn't work?Rebuilding a six-holer is not cheap. <br />Tell the seller you'll be back when he can show you 100 lb. on the gage. <br />The only other way I'd go for a deal like this is if the price was low enough to account for the possible cost of a complete rebuild.<br />Charlie

 

[BrianTindall]

Re: 1988 Johnson 200 Compression

These motors never did have very high compression. My 1988 225 with a 3 year old powerhead was 90psi on all 6. Squirt some oil in each cylinder then check your readings. If they come up, the rings maybe shot or it just may need a decarb.