I have a 1990 , 88hp. Johnson outboard motor it has 118 psi on both cylinders on the same side, but the other two show 132 psi.any suggestions. Will this hurt the motor in the long run.
Hi David<br /> Does your motor run good? If so, there is no need to worry about it. Run the motor a while then retest. Unless your having problems, not running good, making nasty noises, I wouldn't worry.
david,<br />welcome! alcan is right, if it runs good dont worry. This could mean a few things. A motor that has sat up for awhile and has not been ran will have low compression readings. If you can put a hour or so on it and bring the motor back to its normal self. I believe the compression will rise. OR you can decarb like hooty said. That will certainly bring up all compression in all cylinders.<br /><br />Just make sure it has enough lubrication/water you should be ok. <br /><br />I bet there are many outboards out there that do not have perfect matching compressions and still run
Look at the casting numbers on the heads. If they are a set the port head will be one number off (lower) than the starboard head. <br /><br />Most likely they are a set but lets check to make sure. If they arent it could possibly be some of your difference. You didnt mention which side is lower but if its the starboard side it may just be carbon as the guys have stated.<br /><br />Good luck!
Hi Dhadley,<br />Would you explain your answer in a little more detail? Specifically, why the starboard side in regard to the carbon?<br />Thanks,<br />Backlash
On a crossflow thats the side that carbons (cokes) up first unless the block (water jacket) has been vented on that side. For some reason that seems to help with the carbon/coke situation. It also helps water cooled reg/rec live longer. <br /><br />Naturally a thick head gasket or a different head can throw off the readings. If we verify that then we know it, most likely, will be internal. I dont think his motor has suffered any damage yet but its always good to start with the basics.<br /><br />Good luck!
