[Guy]

I changed the oil and filter in the Perkins  gen set this week.  The first time I have done so since owning the coach. We only ran it 20 hours in 18 months,  but i thought it would be cheap insurance. I noticed the oil that came out was rather thick.  I replaced it with diesel rated 15-40. It took 10 quarts. The Perkins has always been a little sluggish to fire up, but after the oil change, it is very noticeable that it starts much easier. I was surprised when walking behind the coach that I was putting out a blue cloud ..... I suspect the old oil was straight 40 , or maybe ' modified" with STP ?

Unless we are boon docking  , I wouldn't / couldn't used this gen set in it's current condition. But then again, I only need it when boon docking.

Any thoughts?

[Fulltiming]

Run the generator under load for a least an hour every month. Generators get really gummed up just sitting.

Does the blue smoke continue after the generator warms up or primarily on startup? Here is some information from Perkins on blue smoke https://www.perkins.com/en_GB/resources/...smoke.html

Overfilling the oil can cause blue smoke. 10 quarts seems a lot for a generator. My Yanmar/Kohler 12.5kw genset doesn't hold that much. About 6 quarts as I recall with a filter change.

[77newell]

On the 77 coach I used to have, it usually put out some blue smoke when cold. That went away as it warmed up. When warm the exhaust had a strong diesel odor. Cold weather starting also needed help, something that Perkins powered tractors were well known for.

It may be worthwhile to have the injectors rebuilt, a lot of the needed refinements could have diminished in 35 years.

[Richard]

Michael has given good advice. Turn on everything, and plug in another coach or two. Seriously load it up, and run it for an hour to clear up the injectors and valves. Idling it, or running with a low load is responsible for fouling the combustion chamber.

If it doesn't clear up, then you can think about if you want to touch it. 20 hrs in 18 months isn't enough to justify much investment.

[bestgenman]

As to the ten quarts of oil,  what does the dip stick show?   And if the oil was thick that means to me that maintenance has been slack, not meaning to be offensive but there are intervals to follow.  Maybe the previous owner didn't service it.

How long has it been since the air filter was changed?  that usually causes black smoke but nevertheless, if the oil was overdue then I would certainly check the AF.

Michael and Richard are spot on , run with as much load as possible frequently.  This helps burn carbon deposits on the valves  that can cause low compression.  low compression will exhibit blue smoke also.

[Guy]

Thanks for the advice from all on this. I noticed that the fresh oil was just as black immediately as the old oil oil,and this was before I started the generator up to check for. leaks after the oil change.
Air filter was pristine.
We have 3 basement air conditioners. That should be a 45 amp load. I will run it an hour as suggested by the Guru's. Have to pick a day when I am downwind from our friend who owns this ranch. I would hate to be evicted?

[HoosierDaddy]

I would run it 5 hours under load then change the oil and filter again. Have an oil analysis done on that oil. It sounds like the old oil's detergents were used up long ago. It is not unusual for diesel oil to be black after running a while but it sounds like the crankcase may be extra dirty.