Merc 454 loss of oil pressure

[Dragonryder]

New to boating. Bought a 1980 CC Scorpion with a (Marine Power ENPAC) 454, Merc Trans w/ 330 TRS. And they guy i bought from basically lied about everything. Found engine block cracked. Trans was garbage. Outdrive was locked up. Everything electrical was rusted and didnt work. Lesson learned and should have had someone with me that knew better.
Anyway.....

Rebuilt engine last year.
Replaced Transmission
Replaced drive
Replaced electrical components and wiring

Finally got the chance to run it on the water. Im using 25-40. Oil pressuer was about 60psi on startup and dropped to a little above 40. After running a while, it rapidly dropped to 20psi. So i cut engine and got towed in. Oil on dipstick was clean and no shiny particles. Found some oil in the bottom of engine bay but i cant tell where its coming from due to getting dark.

What are the chances that the engine is toast?

 

[dubs283]

Found some oil in the bottom of engine bay but i cant tell where its coming from due to getting dark.

What are the chances that the engine is toast?

need to located source of leak, oil in the bilge after initial run after rebuild over the course of a short time span indicates a severe oil leak. should be pretty easy to identify source.

20 psi for oil pressure is still enough to ensure no damage occurred to the internals, my guess is that engine is still sound. good catch and good idea to shut the engine down immediately and get towed in

 

[kenny nunez]

Get a mechanical gauge to replace the sender. That should tell if you are really losing oil pressure. It might just be the sender with an internal leaking membrane.