I am having a hull and mechanical survey within the next week for a 1993 mercruiser 7.4 with bravo 3 drive. The drive was repalced 2yrs ago and shows no signs of the electrolysis problems associated with the bravo 3 drives.
The engine has 480hrs, operated mostly in brackish water, and appears to have been well maintained, with exception of manifold/risers, which may well be original, 18 yrs old.
I expect the mechanical survey will include compression check, probably external temperature checks of cooling system, and general look over. My questions are:
1. Can the mechanic do a cooling system pressure check with boat in water prior to sea trial.
2. Do manifold/riser problems develop over time, or suddenly with engine destroyed.
3. Assuming the mechanic reports that he thinks, from external inspection the mainifold/risers are ok, would it be a reasonable risk to operate the boat remainder of season (mid atlantic area), or have the manifold/risers replaced immediately.
4. Dealer suggested that after purchase, one option to consider is to remove risers and manifolds and inspect, and if ok, clean, boil, regasket and reinstall, is this ever done?
5. Apparently when drive was replaced, waterpump was replaced as well. I assume that this job requires a new impeller and gasket set, but for some reason, a lot of silicone was used as well as the pump base now has excess silicone around it. Any ideas why this would be done? Is silicone in addition to a new gasket required when doing this service. It appears that the pump base was ground down as well, it shows clean shiny metal. Perhaps the pump was not replaced in 16 yrs and the bolts were rusted in place and so forth and it was a difficult job.
The boat was winterized fall 2010 and has been in dry storage, not operated since that time.
Any comments appreciated, Thanks, Ed
The engine has 480hrs, operated mostly in brackish water, and appears to have been well maintained, with exception of manifold/risers, which may well be original, 18 yrs old.
I expect the mechanical survey will include compression check, probably external temperature checks of cooling system, and general look over. My questions are:
1. Can the mechanic do a cooling system pressure check with boat in water prior to sea trial.
2. Do manifold/riser problems develop over time, or suddenly with engine destroyed.
3. Assuming the mechanic reports that he thinks, from external inspection the mainifold/risers are ok, would it be a reasonable risk to operate the boat remainder of season (mid atlantic area), or have the manifold/risers replaced immediately.
4. Dealer suggested that after purchase, one option to consider is to remove risers and manifolds and inspect, and if ok, clean, boil, regasket and reinstall, is this ever done?
5. Apparently when drive was replaced, waterpump was replaced as well. I assume that this job requires a new impeller and gasket set, but for some reason, a lot of silicone was used as well as the pump base now has excess silicone around it. Any ideas why this would be done? Is silicone in addition to a new gasket required when doing this service. It appears that the pump base was ground down as well, it shows clean shiny metal. Perhaps the pump was not replaced in 16 yrs and the bolts were rusted in place and so forth and it was a difficult job.
The boat was winterized fall 2010 and has been in dry storage, not operated since that time.
Any comments appreciated, Thanks, Ed
