1998 Merc 60 compression

[longshanks]

Hi there<br /><br />I have recently purchased a 1998 outboard Merc 45 Jet (60hp powerhead). Although the motor appears to be in very good shape, and the seller states the motor was a very 'good runner', I am concerned about a couple of things... <br /><br />Compression tested evenly across all 3 cylinders at approximately 95. However, this test was done with the motor 'cold'. It has probably been run once (recently) in the last 3 years. Is this compression too low? Should I be concerned?<br /><br />After replacing the spark plugs, it is obvious that there is no spark on the top plug. The owner states this has not been a problem in the past. <br /><br />Lastly, the electric start turned the motor over fine while we tested the compression, but now it does not want to start, although the battery looks fine. <br /><br />I know that the motor has only been run 3-4 times in the past 3 years, but I suspect that it has run on 'old' gas for the last couple of outings. Prior to purchas by the previous owner, it would have only had 3 years of use. Should I be concerned about the symptoms above, or ??<br /><br />thanks for your help<br />longshanks

 

[JB]

Re: 1998 Merc 60 compression

Compression is fine, longshanks. No worries.<br /><br />Bon Voyage.

 

[longshanks]

Re: 1998 Merc 60 compression

Thanks for your reply JB. I understood that compression should be around 130 for that motor. Any clues about why you would not suspect this to be a problem? I recently tested a Johnson 30HP that had been sitting unused for a similar spell, and came up with 110 in each of 2 cylinders. <br /><br />cheers<br />longshanks

 

[JB]

Re: 1998 Merc 60 compression

Compression readings vary widely depending on the guage and technique, longshanks. If all cylinders measure close to each other and over about 90psi using consistent technique I read that as a good engine.

 

[longshanks]

Re: 1998 Merc 60 compression

Thanks alot for your expertise, I appreciate it.

 

[longshanks]

Re: 1998 Merc 60 compression

JB (or others)<br /><br />Can you provide any feedback (positive or negative) on this particular motor?<br /><br />1998 Mercury 2-stroke 60HP - electric start<br />45HP @ jet pump<br /><br />I have read of ignition problems with this motor, and I was hoping to find out if there are any recurring problems with this era/type of motor that I should be aware of.<br /><br />thanks again<br /><br />longshanks