I am re-assembling a mercruiser 1998 4.3+ top end after cylinder head rebuilds. The reason for rebuilding top end was b/c of sticky valve symptoms re: low compression on the 1-3-5 side of the engine. There was plenty of rust in the exhaust valve ports that I figured was causing sticky valves and thus low compression. There was also plenty of salt leftovers in the exhaust risers/manifold although the riser seal b/t the salt water cooling and the inside of the risers was pristine probably due to the new style and retrofitted o-ring/separated exhaust gasket system. So I figured the salt water in the exhaust was either from a relaxed flapper, reversion, or sea water suction into the engine b/c of the issue of the valves not seating.
So after installing heads and rockers per the merc manual re: just torque rockers to 22 ft lbs when #1 is on TDC, I performed a compression check before reassembling further and find 0 compression on the 1-3-5 side and 180 on the 2-4-6 side. An air test into each spark plug hole reveals that one valve in each 1-3-5 cylinder is not fully closed. I relax the rocker arm tension on all the 1-3-5 side and perform an air test on each cylinder when each is on TDC. No leak thru the valves, and pressures up confirming a good seal in the compression chamber. I also tried the Volvo manual recommendation of rotating crank 60 degrees from TDC to tighten all the valves. Same thing.
Do the 1-3-5 valves/lifters just need to be run to get them to relax? Or is this the whole problem with water ingestion?
Also, the distributor #1 is pointing to the 2 o'clock position. Can I simply rotate the drive for it so it points physically to the #1 cylinder?
So after installing heads and rockers per the merc manual re: just torque rockers to 22 ft lbs when #1 is on TDC, I performed a compression check before reassembling further and find 0 compression on the 1-3-5 side and 180 on the 2-4-6 side. An air test into each spark plug hole reveals that one valve in each 1-3-5 cylinder is not fully closed. I relax the rocker arm tension on all the 1-3-5 side and perform an air test on each cylinder when each is on TDC. No leak thru the valves, and pressures up confirming a good seal in the compression chamber. I also tried the Volvo manual recommendation of rotating crank 60 degrees from TDC to tighten all the valves. Same thing.
Do the 1-3-5 valves/lifters just need to be run to get them to relax? Or is this the whole problem with water ingestion?
Also, the distributor #1 is pointing to the 2 o'clock position. Can I simply rotate the drive for it so it points physically to the #1 cylinder?