Generator Help - Blue Smoke

[Bill_Diana]

The generator in my motorhome is 20 years old. It has been used infrequently and only has about 384 hours on the meter. It is a Kohler 5kw Confidant.

The good news first. The generator starts easily and runs smoothly. I'm able to put a large load on the generator and it does well producing electricity.

Now the bad news. The generator has a very small oil leak that I cannot detect the source because the generator is encased in a tight area with virtually no access. The more serious issue is the smoke coming out the exhaust pipe. What could be the cause of the exhaust smoke and how fixable would it be?

Thanks in advance for reading this post and I look forward to all ideas, suggestions & comments.

Bill

[bounder39zman]

agree with OP's, simple oil change can do wonders. We use 15W-40 in all the air cooled gas generators, and diesels as well. Onan ships all the new generator sets with 15W-40. I like Shell Rotella, but use lots of Valvoline Blue and Delvac too. Recommend an oil change, then run for about 8 hours with as much load as you can without tripping c/b's
The Kohler sets were good, smooth running units, 'tho not nearly as popular as the Onan's.

[wa8yxm]

A generator should run a minimum of one hour per month under load (Well at least a half hour and half it's capacity)

THis keeps many things working well. Electronically some components do not age well if not exercised.. mechanically it keeps a nice film of oil on things like the lining of the cylinder.. RUST is not your friend in those places.

[bguy]

I would also suggest PCV issue. On another note, synthetic oils can sometimes leak where Dino oils don't.

[MEXICOWANDERER]

An alternative to Mouse Milk additives is to change the oil to a diesel grade like Delo 400, or Rotella T.

15W/40 grade.

CD grade diesel lube oil has to effectively deal with carbon. The oil's additive package removes carbon many times stronger than what your rings are dealing with. The oil temp should reach 190 degrees and stay there for several hours. The most effective treatment is to run the generator loaded for an hour or so, wait a week and do it again. The repeated soak of CD oil into the ring lands will remove gum.

There is no way CD oil can hurt the engine. Like giving the gummed up rings a dose of the salts. Unless the rings managed to get broken this is an effective treatment

[Bill_Diana]

Thanks to each of you. I'm gong to try each of the items you have suggested. I'll let you know the results.

[Chum_lee]

Is your oil leak new or has it been leaking for a while? If your crankcase breather is plugged, it could force an oil leak and oil burning at the same time. Does the oil (inside the crankcase) smell like fuel?

I second the idea of using ONLY the recommended lubricant and keeping the "genie in a can" inside the can it came in and on the store shelf. (do not overfill the oil) A stuck float or choke in the carburetor could add excess fuel to your oil causing it to leak/burn prematurely.

Think positive. Any oil burning that came, apparently, out of nowhere, can stop just as quickly. (once you find/repair the problem) If the genny starts and runs well and generates rated power, (and doesn't make unusual noises) it's probably not an internal mechanical issue. Check the air filter for oil saturation.

Chum lee

[alaska_dennis]

Try running it without the air filter. It could be a suction restriction.

[newman_fulltime]

Put some lucas oil stabilizer in it run it see if it clears up if not then you need a valve job as the oil is getting in the exhaust valve

[opnspaces]

As you are already aware the blue smoke is oil burning. Matt_Colie has covered the ideas fairly well, hopefully it clears up after a few times running.

As far as the Lucas, I personally wouldn't run something like that in the engine. I have seen the effects of leak stop additives in engines and transmissions. They do initially work by swelling the seals and stopping the leak. But after a short while the seals start to degrade into a gummy mess.

[Bill_Diana]

Matt_Colie wrote:
Bill,

At 20 years and less than 400 hours, I can make two suggestions.

The first and simplest is that the rings are gummed up. A couple of lube oil changes MAY fix that in about 50 running hours.

The rest are not simple given the service resistant install.
It may be that the valve guide seals have dried out or died. That is about the age that rubber parts start going bad all by themselves. The oil change may help this.

Last and not a suggestion is that there is something actually wrong, like a cracked piston.

I have seen these installed and they are not fun to work on.

Matt

Thanks Matt for taking the time to read my post. I'm going to try your suggestion to let it run for a longer period of time.

Typically we only used the generator to run the microwave or perhaps the roof air conditioner for less than 30 minutes while at a roadside rest stop. I do change the oil once every year in the fall before storage. Today, I drained some of the oil and added some Lucas Oil Stop. I think I need to run the generator under load for about 60 minutes and see what happens.

Thanks again Matt.

[Matt_Colie]

Bill,

At 20 years and less than 400 hours, I can make two suggestions.

The first and simplest is that the rings are gummed up. A couple of lube oil changes MAY fix that in about 50 running hours.

The rest are not simple given the service resistant install.
It may be that the valve guide seals have dried out or died. That is about the age that rubber parts start going bad all by themselves. The oil change may help this.

Last and not a suggestion is that there is something actually wrong, like a cracked piston.

I have seen these installed and they are not fun to work on.

Matt