Advice on replacing a rear main seal in an inboard engine

[dcapn88]

Aloha,
I just completed replacing a rear main seal in the Universal Diesel M5444 on my 1986 Ericson 38 sloop. Rather than attempt the job crouched over in the 3 feet of height under my cockpit floor I pulled the engine out into the galley and turned it 180 degrees then set it onto a piece of 5/8" plywood spanning the engine-mount side-rails.
This method of working on the rear of the engine required removing the water heater (aft of the engine), disconnecting the prop-shaft from the transmission flange, disconnecting/removing hoses (coolant, fuel/return, fresh-water, exhaust), and all wiring attached to the engine. And removing 3 of the 5 lag-screws for the engine mounts (I was unable to access the aft lag for the port mount, so left it in place and removed the top/lock nut on the mount and lifted the engine up to clear the mount bolt). With a little help this operation took about 4 hours. Three people then hoisted then engine up and forward to the galley area by using a come-along hooked to strapping around the boom (the main halyard was wrapped around the boom aft of the strapping). After rotating the engine (still on the hoist) we then set it back down in the engine space on a piece of 5/8" plywood that spanned the engine mount-rails (note: engine was set on the bottom of the oil-pan with no problem). Hoisting, rotating, and re-setting the engine took about 1/2 hour.
After removing the bell-housing/transmission, the clutch, and flywheel were removed (using a torgue-wrench for leverage) (this was aided by a helper with a small crowbar keeping the parts from moving). The rear-main seal housing was removed, the gaskets (2) removed, and the seal was replace (note: the seal must be installed with the open-side first into the housing with some grease and a block of wood). This process took about an hour.
Re-assembling the engine, (including torguing the flywheel (then locking the nuts), and clutch bolts), took about an hour and a half, (again with the aid of a helper). Before re-installing the engine I replaced one mount and cleaned and lubricated the other two mounts adjusting nuts (note: the port-side mount was left in place due to the difficulty of re-installing the aft lag bolt, but the lower adjusting nut was installed on it about 1/2" from the bottom of the mount-bolt...able to be adjusted by hand). The engine was re-rotated and pushed into the engine bay (3 people-job) and lowered by the come-along over the port engine mount. The mount lag-bolts were loosely installed and the engine aligned to the prop-coupling by slightly lifting the engine (either with the come-along and/or shims/crowbars), then adjusting the mount-nuts by hand. The lags, prop-connector bolts, and the top mount-nuts were then tightened. This process took about 2 hours (first hour with 3 people, 2nd hour with one person).
Re-connecting the wires, hoses, linkages, water heater then took about 3 hours. The coolant was topped up the air bled from the fuel lines and the engine was re-started. This all took another hour. Total (man-hours)=14.5
If the work was done without moving the engine it might have taken only 5 to 6 man-hours (all by one man), but that man may have been left with a bad back for a long time.

[River Cruiser]

I replaced a lot of crankshaft seals over the years. Caterpillar has special tooling to press them in, I owned several and was able to borrow on occasion ones I needed but didn’t own. Using them makes sure the seal and wear ring are properly installed with no damage.