Perkins 4-108 blow by?

[massnspace]

Greetings.

Considering buying a used sailboat with a Perkins 4-108. 1986 engine with 3600 hours.

In preparation for seeing the boat and to learn some more about this engine, i watched a YouTube video yesterday about a guy replacing the rear main seal on a 4-108. He did a test before deciding to do the seal to see if the motor was any good. He started the motor, took off the oil cap, and felt for air. He felt some air but couldn’t tell for sure what was happening, so he put a piece of paper on it and determined a small amount of air was being sucked in, and stated that was good.

So today when I looked at the boat I did this test, and there was A LOT of air coming out of the fill.

So. Is the engine shot? Is it as easy as that?

Any advice welcome.

David
Seattle

[Lepke]

Originally Posted by massnspace

So. Is the engine shot? Is it as easy as that?

NO.


It has excessive blowby, but that doesn't mean it won't run reliably for years.
But the price of the boat should reflect the condition of the engine. If you're a mechanic, the 4108 is easy to rebuild.

Look for a sheen on the water from the exhaust. That will indicate oil burning.
As compression goes down the engine will be harder to start in cold weather. Glow plugs, block or pan heater will usually fix that.