What is acceptable compression in a 1998 7.4l Mercruiser MPI? At what level of compression are you clear of the possibility of head gasket issue or cracked cylinder head or block? I would like to diagnose and cure but will cut my losses and replace if it looks fatal.
History-Engine overheated, Motor hydrolocked, fixed water shutter, replaced manifolds, Replaced SeaWater Impeller, drained oil from pan and changed filter. Was milky. Put new oil in. Ran. How much residual water in oil is too much? How many oil changes are safe? I cannot seem to get it all. Will this hurt anything. The level does not look to be rising any. Checked compression. 1-130, 2-138, 3-140, 4-122, 5-145, 6-127, 7-140, 8-135 dry. Rechecked 4 and 6 wet. 127 and 134 psi
Do these pressures indicate a problem? Mercruiser bulletin says anything over 100psi and the lowest should not be more than 30% lower than the highest.
145*.70=101.5
How do you perform a leak down test? Is this necessary? What do I need?
Am I in the clear of major damage? Is there another indicator if there is a bent rod or damaged valve/lifter etc from hydrolock?
Motor stalls after accelerating and let back down.
Any ideas of what to check next?
Thanks in advance.
History-Engine overheated, Motor hydrolocked, fixed water shutter, replaced manifolds, Replaced SeaWater Impeller, drained oil from pan and changed filter. Was milky. Put new oil in. Ran. How much residual water in oil is too much? How many oil changes are safe? I cannot seem to get it all. Will this hurt anything. The level does not look to be rising any. Checked compression. 1-130, 2-138, 3-140, 4-122, 5-145, 6-127, 7-140, 8-135 dry. Rechecked 4 and 6 wet. 127 and 134 psi
Do these pressures indicate a problem? Mercruiser bulletin says anything over 100psi and the lowest should not be more than 30% lower than the highest.
145*.70=101.5
How do you perform a leak down test? Is this necessary? What do I need?
Am I in the clear of major damage? Is there another indicator if there is a bent rod or damaged valve/lifter etc from hydrolock?
Motor stalls after accelerating and let back down.
Any ideas of what to check next?
Thanks in advance.
