crackedglass
Petty Officer 1st Class
- Joined
- Jan 4, 2009
- Messages
- 203
I have two Mercury 40 HP twin cylinder engines. One is a 1971, the other a 1985. The 1971 gives me a compression reading of 145/147 on both cylinders, the 1985 shows only 122/122? Both motors are well maintained freshwater run motors, both seam to run great. The reason for my concern is that all of my other Mercury motors show in the 140 to 150 psi compression range on all cylinders. But this recently acquired motor shows less.
I'm just curious if they lowered the compression or could this motor be just weak? Running wise it gives me no reason for concern, but since I was checking the plugs and winterizing it, I figured a compression check was in order.
Do you think that this motor may be 'well worn' or is it normal compression findings for such a motor?
I realize that all that realy matters is that the cylinders are all within 5 or 10% of each other but what constitutes to much wear or noticable wear?
I'm just curious if they lowered the compression or could this motor be just weak? Running wise it gives me no reason for concern, but since I was checking the plugs and winterizing it, I figured a compression check was in order.
Do you think that this motor may be 'well worn' or is it normal compression findings for such a motor?
I realize that all that realy matters is that the cylinders are all within 5 or 10% of each other but what constitutes to much wear or noticable wear?
