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View Full Version : My Generator is Puking Oil!

Steve Herschbach
02-20-2010, 03:59 PM
Some winters we get a rash of generator related issues in our service department. One that pops up now and then is a report that all the oil in a generator gushed out of the carburetor onto the ground or floor.

This happens to units like generators that are running for long hours, and at certain low, below freezing temperature ranges. A four cycle engine crankcase contains the oil that lubricates the engine while it is running. Oil almost always contains a certain amount of moisture, and so the crankcase is vented to allow for vapor to be released from the crankcase. Years ago it simply vented into the air.

But the EPA entered with clean air standards, and venting that moist oily vapor was deemed a bad thing. So manufacturers put a rubber hose on the vent, and routed it into the carburetor. The oily vapor is then sucked back into the motor and burned.

The problem is that in some cases at below freezing temperatures the vapor in the hose starts to freeze. It takes a lot of running hours, but ice can build up to the point where the hose plugs. Now pressure builds up in the crankcase, and in most cases it relieves itself by venting out the carb, taking the oil with it.

In the case of a Honda, the oil alert system shuts the motor down before damage can occur. Although I have seen rare instances where the pressure actually built to the point where the crankshaft seals were actually pushed out from the inside! On motors without an oil alert system damage could occur due to the motor running without proper lubrication.

The fix is to keep the motor running warm. Most units have air vents with fan blades in the recoil area of the unit designed to suck in outside air and direct it over the head of the motor to keep it cool in warm running conditions. That is great at 70 degrees but not so great at 10 below. Remember when a cold running car or truck needed some cardboard put in front of the radiator to keep the vehicle running warmer in extreme cold temperatures? Well, duct tape covering 3/4 of the cooling vents will keep the unit running warmer and help head off vent freezing issues. The best fix is an enclosed, insulated box set up with external exhaust and incoming air vent to keep heat produced by the motor inside the box, again preventing the problem.

I'm told this problem was common on the North Slope before maintenance people figured out what was going on. Just another fun side effect of living in a cold weather climate!

02-20-2010, 08:36 PM
Boy I had to smile at this post .... thinking back to the first old Honda 1000 watt generator I had. Those first ones had that open cowling design and made the problem even worse. Yup .... first winter we ran it the "puking oil" syndrome happened. I figured out right away what the problem was, but no one told us to run the thing in a box to keep it warm ! Blew the crankshaft seal . Since that time I have run into countless folks with the same sad tale.
The newer Hondas are much more enclosed and not AS susceptible to this problem. Although they still need to be used in some kind of enclosure when it is cold or the air vents become solidly packed with frost!

Good of you to post this issue Steve. Maybe it will save someone a headache :)

Brian Berkhahn
10-02-2010, 06:42 PM
Huh.. I wonder if that's why I have such a hard time starting my EU2000 in the winter. Usually I have to warm it up with the sunflower heater for a while before it starts.

Now if I could just solve the surging problem with the motor.


10-02-2010, 07:20 PM
In my experience with the Honda EU2000, the surging is due to the terrible gasoline we have on the peninsula. Using Sta-bil in the gas helps a lot, but once a year I have to take it into the shop and have them fix it. Cost is about $75.00. Not too bad seeing that I ran the generator 12+ hours per day from mid May until October.

10-09-2010, 06:18 PM
The 2000 seems very fussy in the cold. In really needs to be warm to start. It seems the oil alert system on these things won't let it start until you have oil pressure. In the cold it takes lots of cranking to acheive that, then if it doesn't warm fast enough when running the alert will shut it down.
These Honda gens are great units but they have to be in some kind of enclosure when it gets cold. Mine will start to 'gallop' if I try to run it in cold wx without the box.

10-09-2010, 10:19 PM
Interesting, I too have experienced all that with my H2K. Still an awesome generator though.

Brian Berkhahn
10-11-2010, 04:14 PM
Somebody told me once that the "gallop" or surging was due to the jetting. These units are jetted for California which doesn't work all the great for Alaska's cold weather.
I agree.. I love my EU2000I but had to buy the EU6500I and put the wireless autostart on it, now I have my EU2000I for a backup.