What about compression testing and engine surveys?

Will you be doing a compression test on the motor when you survey the boat?

All surveys include an
external inspection of the engine and drive train, fluid levels, belts, hoses, wiring, etc., at no additional cost.
The newer outboards and inboard engines have
computer download capabilities that will generate a report of diagnostic problems
and usage. It will show any alarm events of overheating etc., and hours of use broken down to time spent at different rpms. This is
useful to show how hard the boat was driven. (Over-revving events indicate the boat was driven airborne off waves which will seriously
damage engines and drive trains).  Note that the software required to get a download is proprietary to the engine manufacturer and
must be done by a dealer/service centers.  Minimally, for any 4 stroke engines, (gasoline inboards, diesel and 4 stroke outboards) I
strongly recommend
sampling then analyzing the lubrication oil after running the engine for a period of time until it has warmed up
or after the sea trial, (see the Oil Sample FAQ). Only a
sea trial* will determine the ability of the engine to perform under load to
manufacturers specifications. A
complete engine survey by an independent certified technician will only be recommended if either or
both the oil sample analysis or observations during the sea trial point to internal problems with the engine. The cost of an oil sample is
minimal compared to a full engine survey. The sea trial is included in a Pre-purchase Survey, (See pricing section for details). A
cylinder compression test will only be recommended for a 2-stroke outboard that either fails to run properly on the sea trial or a sea
trial isn't possible. I can perform this test myself on most outboards after the engine has been warmed up.

To summarize, a visual inspection of the engine and drive train, sea trial and engine oil analysis is basic. Only if indicated will a complete
engine survey be recommended and then should only be performed by a qualified factory trained technician with the proper equipment.
A compression test will usually be performed during a complete engine survey. Keep in mind, a compression test alone is not a fail safe
indicator for the condition of the engine and should not be overrated or routinely expected in a Marine Survey. It will show problems with
heads, gaskets, valves, pistons, rings or cylinders but tells nothing for bearings, pumps, electronics, carburetors, fuel injection and all
the rest of the components that make up an engine. Ask for credentials for anyone offering to perform engine surveys.

*Considering the high cost of diesel engine repairs or replacement it is strongly advised to include a certified diesel technician to be on
the sea trial for larger yachts with diesel power plants.  Turnstone Marine Survey will make the arrangements to do so with a reputable
local professional.
From the Surveyor's Notebook