How check engine pre purchase?

[massnspace]

Looking at some older sailboats for sale. 80s vintage.

What can one do to check the engine before buying?

Compression check?
Leak down test?
Oil analysis?
Heat gun on running engine?

Looking for any advice here.

Thank you

David
Seattle

[S/V Illusion]

An engine survey inspection by a reputable marine mechanic as a prerequisite to purchase similar but in addition to the typical boat pre purchase survey.

[grantmc]

I think this is a nice summary of engine checks of an inboard diesel:
https://www.jamesmarinero.com/buying...engine-checks/

[Bycrick]

When I bought my current boat, after spending all day crawling over the boat, made a firm offer, subject to sea trial, and hull, rigging and motor surveys. The hull and rigging surveys came up clean, the engine surveyor saved me $25k. I didn’t find a "mechanic." I found an engine surveyor who specialized in testifying in court. And worth every penny.

[skipperpete]

Originally Posted by massnspace

Looking at some older sailboats for sale. 80s vintage.

What can one do to check the engine before buying?

Compression check?
Leak down test?
Oil analysis?
Heat gun on running engine?

Looking for any advice here.

Thank you

David
Seattle

The best and quickest engine test you can do is to unscrew the oil filler cap while the engine is running to establish how much cylinder blow by is present. Be wary of engines that have crystal clear oil and a new filter, oil analysis won’t help much if the owner just did a flush and refill. There are many other quick tests you can do but most are engine type specific so knowing what engine you have narrows down what you need to check. A cylinder leakage test is worth doing as is a compression test but often the owner or broker won’t allow intrusive testing.

[roryboy]

Look at all fluids. Do you see water in oil or oil in water? If not, good.

Start engine. Does it start easy? If yes that is good.

Look at exhaust. Does it clear quickly at startup? If yes good.

Any blue, black or white smoke while running at idle or under load? If not, good.

Run engine hard underway. Does it run up to Max RPM? If it does, good.

Run engine hard for about 1/2 hour. Does it make temp and not over heat? Then good.

Most everything else is maintenance or deferred maintenance.

[Fintry]

Originally Posted by Bycrick

When I bought my current boat, after spending all day crawling over the boat, made a firm offer, subject to sea trial, and hull, rigging and motor surveys. The hull and rigging surveys came up clean, the engine surveyor saved me $25k. I didn’t find a "mechanic." I found an engine surveyor who specialized in testifying in court. And worth every penny.

Amen. Many people who do engine surveys expect to do the repair work that they suggest needs doing. You are much better off with someone who knows the brand of engines you are buying but doesn't do repair work. During the Morning Light survey two weeks ago, I learned some things that I didn't know about my main engine.


Jim