Question on Compression.

[AtlDawg]

I am looking at a 1991 Evinrude 150 XP that has 96 lbs compression on 5 cylinders and 92 on the other. Is this the normal compression on this engine or is it a little low and how about the 4 lbs difference on that one cylinder? Any help would be great.<br /><br />Thanks

 

[JB]

Re: Question on Compression.

Hi, Dawg.<br /><br />Ordinarily readings below 100psi would be suspect.<br /><br />However, readings on the same engine may vary as much as 20psi because of variations in guages, technique, whether the engine was cold or warm, whether throttle plates were fully open, and other factors.<br /><br />Because all cylinders read within a few psi of each other I would say you have a good engine there.<br /><br />Good luck.

 

[R.Johnson]

Re: Question on Compression.

I don't think I have ever seen two compression guage's that were in agreement. I now start with a compression test, and if there is any guestion I follow up with a leak down test.I would like to someday find a truly accurate pressue guage, and make up a small pressure tank to check my guages again'st. They would not have to be in agreement, you could just add, or subtract the difference.