Full service on a Cummins 5.9BTA 315hp

Impellers, zincs, oil, filters, incl gear shouldn’t be more than a day of labor so figure $1000-1200 for both.

supplies should be about $500 for both . They re pretty small engines.

Not sure about the aftercoolers but can’t imagine more than a day of work, if that.

If there are no receipts, don't trust a dam thing on past service.
We were just reminded of this in another thread.

It took us two days for everything on later Cummin and Detroit engines.
Setting up, The service, Cleaning up, Delivery..
That did not include R&R the air coolers.
This was the norm for engines that we had already serviced or was properly serviced before.

I remember burning up hours removing zinc plugs that had never been services for years,, if ever.
Ever hour that went by on the phone with the owner, texting him pictures and the reply,,, The previous owner said this, that and all was serviceable.

Then the hours trying to service air coolers that had never been serviced.
Seized bolts, weeping seals..

Oh, the Sheerweed raw water pumps. A problem point itself but a mess if not dealt with.
Yep, cleaned up many of these messes on supposed perfectly maintained engines.

One of the members here taught me long ago, No Proof, Didn't happen.

Survey the engines well. Very well.

I remember one supposed well maintained boat broke a motor mount during sea trials. Yep, left front under the sheerweed raw water pump.
It was just rust that held the engine up till,,,
Surveyor and proposed buyer could not get off that boat fast enough.

My Previous boat had 315 Cummins. I did all that work on my own engines and as stated above, about a day disassembly and bring home clean after coolers and reassemble paint etc. heat exchangers I would bring to radiator shop then a day reassembly. I documented with picture and receipts for O-Rings, gaskets etc. I had to change multiple Sherwood pumps (need to Jack up engine and remove left front motor Mount then pump removal is easy. I finally switched to Seaboard pumps and never changed a pump again. The splined impellers are much better and you can’t drop the key into the intake hose (done that a few times). When you purchase the Seaboard impellers they come with a removal tool and impeller changes can be done in about 15 minutes.
Anyway when I sold boat the pictures, parts receipts, and maintenance log were well documented. If the maintenance was truly done the owner should be able to show you.

Yep