[C320-list] Sudden blue smoke, Perkins M30

[mseyler at cox.net]

Frank,

Sudden oil burning does sound unlikely. The usual source of oil in the combustion chamber is either bad rings or worn valve stems allowing oil in from the rocker arm area, and neither of those usually happens suddenly.  Could the smoke actually be white smoke from unburnt diesel? Or white steam from coolant?  Either one could cause the sheen you see on the water.

A bad head gasket could potentially cause either of those problems.  (Loss of compression from bad seal between the head and the block, or coolant getting into the combustion chamber.)  If the head gasket is bad, you should be able to see a loss of coolant, and the lube oil can turn milky if the coolant gets into the lube oil.

Alternatively, could some debris have gotten into the "clean" side of the secondary fuel filter when you changed it, and possibly gotten from there to the injector pump or the injectors?  You can take the injectors out and take them to a diesel shop, where they can test the release pressure and the spray pattern.  If they are bad, they can be re-built, or you can get new ones from Parts4engines.com for $112 each, plus shipping.  I've never had to check an injector pump, but your mechanic may be able to test it in place.  If it has to be replaced or re-built, be sure to keep track of the shims between the pump and the block, as that's how Perkins adjusts injection timing.

While the injectors are out you could also get your mechanic to do a compression test.  That would tell you for sure whether your rings, valves and head gasket were holding compression.  But with so few hours on the engine, I usually wouldn’t expect the metal parts to fail or wear out based on the maintenance you describe.

Good luck, and please let us know what you ultimately find to be the cause of your problem.  Much of what I've learned about diesel engines has been from hearing about folks' problems, and how they were solved.

Mark Seyler
S/V Reality,
Catalina 320, #232
New Orleans, LA



-----Original Message-----
From: C320-list <c320-list-bounces at lists.catalina320.com> On Behalf Of P.F. Ross via C320-list
Sent: Saturday, February 17, 2024 12:11 PM
To: C320-List at catalina320.com
Cc: P.F. Ross <pfrstl at gmail.com>
Subject: [C320-list] Sudden blue smoke, Perkins M30

All,

We had been motoring yesterday at our normal 2600 RPM for about an hour when suddenly the engine lost power, revs dropping down to 1800 or so.  At that same instant I noticed smoke from the exhaust like I had never seen before.  I throttled back, gave the admiral the wheel, went below, removed engine covers and checked everything.  All appeared normal.

We were just about to enter a busy harbor, so not knowing what was going on I decided to shut the engine down and called for a tow.  We were about 10 miles from home so decided to go back there.  Fortunately, winds were light and seas were flat.

The week before I had changed both fuel filters and the fresh water impeller, preparing for a cruise.  Fuel tank was topped up with the same Shell brand terrestrial diesel I have used for the past 9 years.

I have owned the boat since new (1994) and the engine has 550 hours, the majority of those accumulated since I moved the boat to SW FL in 2015.
Regular oil, filter and coolant changes are known since I have done them all.

Today at my dock, the engine starts and seems to run ok, but still belching clouds of what I would call blue smoke and is leaving a sheen on the water.  It also has a peculiar smell, perhaps somewhat sweet.

So it seems like oil smoke, but for the life of me I cannot imagine what failure would cause sudden oil burning.  I suppose a fuel injector could suddenly malfunction (I have never messed with the injectors) but that would seem to be black smoke.

I will try to find a diesel mechanic to come check it out next week but thought I would see if anyone on here had an idea of what may be going on.

Thanks and regards,

Frank Ross
Beta Wave #206
Naples, FL