Oil leak

every engine leaks from the bottom of the fuel lift pump. In fact when the engines arrived in Canada new in the crate they were leaking from the fuel lift pump. It's the most common leak on these engines. It's because the fuel lift pump flange warps after it's installed. Some are worse than others. Tightening it doesn't help in my opinion unless the bolts are loose.

Fuel Lift pump (better design)
https://www.ebay.com/itm/Ruggerini-Fuel-pump-Marine-engine-FIDO-RD-1-CRD-1/152139263679?hash=item236c34eebf:g:nHEAAOSwwpdW71QL

This fuel pump doesn't warp and therefore does not leak oil. The original Bukh fuel lift pump flange warps on both axis's and leaks oil as a result. This new one has a thicker stronger designed flange. You use the gasket it comes with and it works great. All you have to get are 2 x cap screws as there isn't enough space to use the nuts that are used on the original pump. This means you remove the studs and replace them w/ cap screws (ones that use an allen key)