[Mr. Haney]

I have a 1975 Mercury 1500 with compression as follows; 124#1-120#2-120#3-123#4-112#5-118#6. It also has a leaking feul pump and for some reason I'm not sure of, the plug in number 5 is a different make and worn out. Any ideas friend?

[corm]

Hi Mr. Haney,Your inner water jacket that cools the exhast ports sounds like it is leaking. This creats steam and coroades things faster than normal. This would also explain why the bottom two cyl are low on compression. Fix the pump to as it will cause a lean burn problem at mid to high speed, a bad thing.Your bottom two pistons are probably scuffedas it is now. You can tell buy looking when the outer water jackt is off. You have to pull the powerhead to do this. So run the motor down the lake and turn the key off. After everyone settles down quickly pull the plugs out. If there are water beeds on them or they look milky, then the inner jacket gasket is the problem.------------------...have fun...cormcubic inches = powerpower = speedspeed = FUNEmail me if you need to.