Mercruiser big block engine swap

[Patrick D]

Hi,
I am new to this forum and hope that someone out there has done a 454 engine swap. I have a 1987 Gen IV 454 that has finally rusted out (raw water cooled).
I have found a couple of used Gen V and Gen VI engines. It appears as though a Gen V engine will swap in, though I will need to wire the electric fuel pump, and will need to make sure that the longer water pump will fit in the engine compartment. The coupler, engine mounts, and exhaust look the same. I've checked some mercruiser parts sites to confirm that the part numbers for these items are identical for both the Gen IV and Gen V's. I'd like to install a used engine, rather than spring for a $3,500 reman (I will need to pay the core charge as my block is junk). Does anyone know if this swap is as easy as it appears to be? The boat is a SeaRay 250 Sundancer and is in good shape. Over the last few years, I've changed out the gimbal ring, bellhousing, and replaced the outdrive, so it is worth dropping an engine in it..........

Thanks!

 

[alldodge]

Hi,
I am new to this forum and hope that someone out there has done a 454 engine swap. I have a 1987 Gen IV 454 that has finally rusted out (raw water cooled).
I have found a couple of used Gen V and Gen VI engines. It appears as though a Gen V engine will swap in, though I will need to wire the electric fuel pump, and will need to make sure that the longer water pump will fit in the engine compartment. The coupler, engine mounts, and exhaust look the same. I've checked some mercruiser parts sites to confirm that the part numbers for these items are identical for both the Gen IV and Gen V's. I'd like to install a used engine, rather than spring for a $3,500 reman (I will need to pay the core charge as my block is junk). Does anyone know if this swap is as easy as it appears to be? The boat is a SeaRay 250 Sundancer and is in good shape. Over the last few years, I've changed out the gimbal ring, bellhousing, and replaced the outdrive, so it is worth dropping an engine in it..........

Thanks!

:welcome: to iboats

A 454 is a 454, is a big block and as you mentioned wiring and externals are the only differences. I pulled a 454 and replaced it with a 504 MPI, other then wiring it all fit

 

[tpenfield]

The Mark IV and the Gen 6 are more the favorite engines versus the Gen 5. So, if you can go with a Gen 6, that might be better.

I had a Mark IV in my 242 and it rusted through after 20 years of salt water use.

 

[Patrick D]

Ok, Thanks for the feedback. I'm much more comfortable making an offer on the Gen 5 now. Another bonus is that the gen 5 is closed cooling and comes with everything except the seawater pick-up Thanks again