Replaced port aft one on my Yanmar 4JH2E recently. Did it myself with a friends help.
The mount was $135 (with a discount) from local Yanmar dealer.
ring front and back. We firmly secured topping lift on the boom. Then used a 4:1 block and tackle (1/2" line) attached to both lifting rings. Aft ring was about 6" too far aft to have direct run to block. But, used it anyway.
Took up tension on lifting system and removed nuts on broken bolt then removed old mount. We only needed to lift port side of engine about 1" .
Installed new mount.
Aligned engine/transmission/coupling/prop shaft to +/- .002".
Total time to R&R mount and get initial alignment was 3 hours and another hour for site prep (clear access to mount, rig lifting, find the nut that drops under the engine...etc).
R&R the mount is easier with two people because one is operating the lifting device while the other is watching the mount and trying to remove the broken bits. It could be done by one person but would take much longer.
Total time to finish alignment (over a couple weeks and several trips motoring around bay to seat new mount) was about 2 hours.
Yanmar says to check alignment after 10 hours and 50 hours or something like that.
There is no mechanical skills involved in this project
- just careful thought about the hoisting and patience working in restricted spaces.
The alignment process is tedious and time consuming. If you are not used to using thin feeler (strip) gauges you might want some guidance.
Access to our aft motor mounts is from front or back. I took the time to remove the alternator
and a pump and a couple of tubes/hoses from the side of the engine so I could then lay on top of the engine (with appropriate padding) to work on the mount and transmission
coupling, from above. However, some of the work required I lay on the galley
floor and reach the bottom of the mount.
The key is to take the time to create a clear work area and make sure you have bright light to see the little details.
Had a bit of excitement first time we took boat out to bay after first alignment. A low pressure diesel
tube broke at a fitting and sprayed vaporized diesel
everywhere. Eventually realized my knee had been pushing on the fitting while I was laying on top of the engine doing the alignment.