Broken cylinder ring?

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Broken cylinder ring?

Handy13
Started generator up Friday evening.  Ran fine for 5 seconds.  Then began emitting white smoke.  Stopped generator.  Tried to check oil.  Oil came pouring out.  It was filled with pressurized bubbles.  Sopped up all of the oil that came out with paper towels.  Lots of oil.  After that, I could not pull the starter rope.  Frozen somehow.

So, since I cannot find a maintenance manual to see how the motor is configured I have to guess how high-pressure bubbles could get into the oil.  My best guess at the moment is that a cylinder ring broke?  And that is now preventing the cylinder from moving?

Generator has less than 200 hours total on it.  I use it for running a telescope and laptop for astronomy when I go out in the field.  I always drain all of the gas after use and run it until it runs out of gas.  I do this to prevent "surging" which caused me to go to a repair shop a few years ago and they said I needed to do that in the future...  

Have really loved the quietness of this machine and the 300 watt low-power setting is perfect for my use!

Any better guesses by anyone will be much appreciated!

Thanks,

Howard
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Re: Broken cylinder ring?

CycleRob
What model is it ??
Talent, On Loan, From God  --Rush Limbaugh--
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Re: Broken cylinder ring?

Handy13
Hi,  Thought I mentioned it.  EF1000IS.  Anyway, problem corrected by local repair shop... They say:

"Engine was hydro locked due to being overfilled with oil or tipped over.  Muffler full of oil.  Changed oil, serviced and ran unit long enough to burn oil out of muffler.  Load tested good."

So oil was apparently on the spark plug side of the cylinder.  I still don't see how it could get there.  Unit
was never tipped over and I didn't think oil was overfilled.  Again, it ran fine for 10 seconds then began blowing smoke.  I still don't see how oil became filled with pressurized bubbles during that time.  Somehow after I stopped the generator the oil found its way to the area of the cylinder where the spark plug is.  It could not be moved then since the oil is incompressible.  They said if it happens again, remove spark plug and clear the oil out of the top of the cylinder area.

So now I know what to do but it still disturbs me that I don't see how the oil could get up into the cylinder
area above the piston.  Seems like it would have to enter through a valve?  How did the oil become filled with pressurized air bubbles?  I hate it when I don't know exactly how things work.  :-)

Thanks,

Howard
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Re: Broken cylinder ring?

CycleRob
This post was updated on .
The oil gets overfilled by either the person adding the oil (on a tilted surface?) -or- by fuel dilution caused by a sticking/leaking carburetor float valve with the fuel valve left on when the fueltank normally pressurizes from a barometer change and/or excess heat in the storage location.

 Fuel dilution is very bad for the motor if it is run with that gasoline contaminated oil as a plain bearing lubricant. It is very easy to diagnose by opening the oil fill cap and taking an up-close whiff of the odor that emanates. The servicing dealer should have made that sniff test Job-1.

 First, overfilling the oil decreases the crankcase airspace above the oil, forcing the normal up-n-down piston movements to generate much larger amplitude, more powerful pressure pulses. The elevated, overfilled oil also gets stirred up so much more by the (now submerged) crankshaft counterweights that it overwhelms the oil separator component built into the valve cover, allowing liquid oil to travel thru the vent tube into the carburetor air inlet, That would generate a huge, dense smoke cloud when the engine runs. When the engine stalled or was shut off, the crankcase vent's remaining oil mass drained into the cylinder (intake valve must have been open) and created a super high compression ratio that approaches the feedback of a hydraulic lock.

Here is a pic of the EF1000iS tiny oil drainback hole from the (non serviceable) oil separator built into in the valve cover.
http://i142.photobucket.com/albums/r87/CycleRob/YamGen/CIMG0122.jpg~original

The dealer mentioned the Genny was "serviced", so I guess a valve adjustment and an inspection/cleaning of the disk check valve and drain-back hole was made.

 Did someone else add the oil to an excess?
Talent, On Loan, From God  --Rush Limbaugh--
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Re: Broken cylinder ring?

Grumps
In reply to this post by Handy13
After reading your post I am wondering if you are tilting the generator to pour the gas out of the tank. If that is the case that could explain how oil got up into the top end. If you are not going to use the unit for a while, open the back cover and open the petcock and open the drain screw on the carburetor bowl and drain all the fuel into a container. Close the petcock and make sure the float bowl is empty then close the drain screw. You should never have problems if you do this.

Another thought is if there are gas stations near you that have ethanol free gas always use ethanol free fuel in your small engines.
http://pure-gas.org/
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Re: Broken cylinder ring?

Handy13
Hi,  Thanks for comment.  No. I always keep generator upright, siphon gas out of tank, then run it til it quits,
then open carburetor valve and drain it completely.  I do that to prevent "surging" that happened a few years ago.  The repair guys said to do that and it would keep everything running nicely in the future with no build-up of junk that caused surging.  I might have had the oil overfilled.  I still don't see how the oil could get up into the top of the cylinder.  Seems to me it either has to slip past the rings or somehow enter one of the valves.  Then I still don't see how pressurized bubbles could have gotten into the oil storage area.  

I guess I don't "really" need to know that but I like to know how things work so I can make doubly sure I don't do something stupid again.  (I am a mathematician and software engineer - In my job I absolutely HAVE to know how things work.  In 1965 I accidentally disabled processing of the Ballistic Missile Early Warning system observations via a software modification in the SPACETRACK system.  Got called in the middle of the night about it.  Got used to knowing EXACTLY how things work, since in those days, a software error could come very close to causing World War III...  Literally...   :-)  )

Thanks,

Howard
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Re: Broken cylinder ring?

Grumps
Just to help you understand a little better. There is a certain amount of air space in the crankcase, as the piston goes up in the bore the air volume has to expand and when the piston comes down the volume has to decrease. So there is a small passage into the breather system with a disc valve that allows for the movement of air back and forth into the crankcase to allow for this. Now if you have to much oil in the unit the crankshaft will whip the oil into a froth and this along with the air can get pushed into the breather and sucked into the intake. Hope this helps.
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Re: Broken cylinder ring?

Handy13
OK!  Thanks much!  That helps.  No diagrams I have seen of any engines (and I am surely not not an expert) shows this additional pathway.  Your explanation is what I was looking for!  Some rational explanation of how what occurred could possibly have occurred.  If the only three paths for the oil were (1) through the rings. (2) through the intake valve, (3) through the exhaust valve as shown in http://auto.howstuffworks.com/engine1.htm then I could not see how my engine did what it did.  You have indicated that there is a 4th path that nobody seems to describe in any diagrams I have seen...

So the bottom side of the piston where the oil is needs to have some way to not pressurize on the down-stroke and depressurize on the up-stroke and you are describing a 4th pathway that is necessary.  Otherwise the motor would lose a lot of power due to pressurization/depressurization of the chamber where the oil is as the piston moves up and down.  

So the warning about overfilling the oil is due to this 4th passageway.  I guess they didn't want to call too much attention to what would happen if you overfilled the oil.  Would have been nice to know in advance though.  In addition, this generator has no oil-fill line so it is really hard to tell when it is "over-filled".  :-)  Or under-filled.  

The Owners Manual shows a picture and says:
ENGINE OIL
Make sure the engine oil is at the upper level of the oil
filler hole. Add oil as necessary.
NOTE:
Place the generator on a level surface and check the
oil level of the oil filler hole.

I thought that was how I had it.  It must be pretty sensitive to oil depth...

Thanks very much!  You have supplied the explanation I needed...

Thanks,

Howard
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Re: Broken cylinder ring?

CycleRob
Handy13 said:
"So the bottom side of the piston where the oil is needs to have some way to not pressurize on the down-stroke and depressurize on the up-stroke and you are describing a 4th pathway that is necessary.  Otherwise the motor would lose a lot of power due to pressurization/depressurization of the chamber where the oil is as the piston moves up and down."

 That is way off base. Consider the pressurization/depressurization of the chamber where the oil is as if it were an "air spring", where very little energy is lost, especially when the crankcase chamber air volume is large enough to make those piston pumping fluctuations less dramatic or influential. To understand how an air spring is efficient, compare it to using a pogo stick. Once you climb on and start jumping around, it takes much less energy to keep going.
The crankcase venting system DOES NOT allow those pressure changes to be vented both ways, as that would generate HUGE pumping losses!! The crankcase venting system's floating disc check valve imbedded in the valve cover very efficiently maintains a very slightly negative air pressure inside the crankcase. This minimizes crankshaft oil seal leaks, gasket weeps and valve stem oil weepage into the inlet and exhaust ports. Because the piston's oil control piston ring nearly "wipes" the cylinderwall clean of excess oil regardless of the crankcase pressure, it will be the smallest contributor to oil burning, unless there is cylinderwall surface scoring.
If you follow the small rubber hose connected to the valve cover you'll see it goes to the intake airbox, near the carb inlet. That is how a tilted genny oil overfill, that will be immediately whipped up by the submerged crankshaft overwhelms the tiny oil separater drain back hole in the valve cover and soon gets directed into the combustion chamber. It is a simplified crankcase ventilation system common to EVERY 4-stroke engine made since the late 1960's. Even cheap push lawn mowers have the same system, by law. Besides the law, it's normal operation cleanly burns nasty and unburned crankcase blow-by fumes and when an engine is heavily loaded it provides a small amount of beneficial "top oil" that lubes the cylinder walls.

About the correct oil fill level, the wording is almost correct. The "upper level of the oil fill hole" is a little confusing if taken literally. It is actually the lower edge of the opening at 6 O clock, where if you fill the oil right it will be on the verge of pouring out the opening. It MUST be on a level surface, which does NOT include your driveway, back yard or garage floor. Another way overfilling occurs is if you start a cold genny then decide to immediately shut it down to check (then re-fill) the now lower oil level.
Talent, On Loan, From God  --Rush Limbaugh--
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Re: Broken cylinder ring?

new&confused
I want to thank you guys for this post.   I have tried to save money by buying quality used generators.  My wife is disabled and travels with my daughter to horse events  - needs power.  Just bought a used yd4000 and it started throwing out white smoke after a short time using it.  I almost went after the guy I bought it from thinking he saw another sucker coming.  Based on your posts, I can see there is a great chance I caused the problem moving the generator.  Once I had it on the ground and running on its own the white smoke stopped.  Going to do a proper service and see if that solves the problems.
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Re: Broken cylinder ring?

CycleRob
In reply to this post by Handy13
Handy13,
Two things;

First, About the "crankcase ventilation system", common to every 4-stroke engine made, the pulsating positive/negative pressure waves generated by the underside of the piston when the engine runs happen so FAST that the measured pressure would be a vibrating average that is close to normal atmospheric pressure (outside air). For the simplified system in most all small engines there is a check valve embedded in the valve cover that "sways" those violent pressure waves toward a slightly negative value for the crankcase internals by opening for the slightly positive pressure and closing for the slightly negative crankcase pressure waves. This is to expel the minimal piston blow-by gases and minimize the chances of engine oil leaks from the crankshaft seals and gaskets between mating parts.

Second, There is another possible way that gasoline could get into the crankcase oil, WHILE THE ENGINE IS RUNNING . . . a bad fuel pump (Part 5 below). The black plastic fuel pump operates a synthetic rubber diaphragm with the low amplitude, rapidly pulsating crankcase pressure waves to very efficiently pump fuel from the gas tank to the carb at low pressure. If the diaphragm cracks or partially dissolves it will allow gasoline to enter the crankcase via the black rubber pulse hose (Part 11 below) connected to the crankcase in plain sight. That would thin out the oil so it "bubbles" AND raise the oil level. You should remove the pulse hose where it connects to the brass crankcase fitting. To clarify, the hose is the one that connects the fuel pump to the crankcase. See if gasoline drips from it and/or it has a strong gasoline odor. There should be ZERO gasoline odor! Then check your oil at the dipstick for gasoline odor and a higher oil level. The gasoline thinned out oil will also make the air-fuel ratio richer via the crankcase ventilation hose coming from the valve cover. Check the oil odor to be ABSOLUTELY SURE there is no gasoline odor -and- the level did not get higher, as gas-in-the-oil WILL permanently damage many moving engine part$, making parts replacements NOT an option.  Sadly, the dealer "tech" may not have noticed the strong gasoline odor in the "service" when the oil was changed, so "trust but verify", as it is really important!
 Fuel Pump Diagram
Talent, On Loan, From God  --Rush Limbaugh--