I have a 1998 7.4 mpi sn 0L042350. The long block was replaced in 2016 with a Mercury reman by a Mercury shop. I recently rebuilt the top end because I had been experiencing some performance loss and confirmed that coolant was getting into some of the cylinders. The rebuild went well, but the compression numbers I saw before and after the rebuild are about the same.
Prior to rebuild, I had 130-155psi on port side, 175-185 on stbd. After rebuild, I am seeing a more consistent 150-155 on port side, and about the same as prior 175-185 on stbd.
Any thoughts on this? Heads were taken to the shop and surfaced and valves ground, new seals, etc, so I think that part of the equation is good.
What else could be causing this issue?
Thanks all
Prior to rebuild, I had 130-155psi on port side, 175-185 on stbd. After rebuild, I am seeing a more consistent 150-155 on port side, and about the same as prior 175-185 on stbd.
Any thoughts on this? Heads were taken to the shop and surfaced and valves ground, new seals, etc, so I think that part of the equation is good.
What else could be causing this issue?
Thanks all
