Hatz engine - foaming oil

[mike90045]

Today, I changed the oil in my back-up generator (Robin-Subaru-Hatz) and drained the old (15 hr break-in oil) and added new, just like I did when I took delivery.  Checked the dipstick, cranked it up for 90 seconds and shut it down.    Checked the oil, and the crankcase was all foam     (Napa 15-40 Universal gas-diesel oil)  (1.1 liter, capacity Hatz 1b-30)

Sucked some out with a turkey baster, after 10 minutes, the foam "mostly" subsided but still had lots of very fine bubbles in it.

Thinking I'd gotten some water condensation in my oil jug, I drained the oil foam, tilted the engine to be sure I got it all out, and refilled with Delo 15-40, but just shy of 1.0 liter, thinking I'd overfilled it and the crank whipped it up into foam.    Started it up, 90 seconds and again, a crankcase full of foam.   

Any ideas what's happening here ?   The half hour warm-up run I did with the old oil (Napa universal) was just fine, only slightly dirty when I drained it, and I'd gotten just over a quart out when I poured the sump back into an old bottle.

I'm letting it sit overnight, will check the dipstick (fresh oil in a nearly new engine is next to invisible) in the AM. (and look for answers here too)

[mobile_bob]

sounds like an overfull situation to me

is it possible the unit holds less oil that is shown in the manual? do they offer a higher capacity pan
or crankcase that this spec is meant for?

interested to see what you come up with.

has it ever foamed up before?  did you measure the breakin oil to see how much was actually in there?



bob g

[mike90045]

I measured the break-in oil the same way.   The "sump" which comes on some engines, adds 1 liter to the crankcase, and is not present on my engine.  I'll try it again later today and update tonight.
  Mike

[Henry W]

I wonder if the oil pump is sucking air. Is the oil screen type filter before the oil pump? I don't have a schematic for these engines but it looks like the filter might be above the oil level and this could mean the oil is sucked into the filter. If the o-ring is cut or damaged on the filter housing that slides into the block air could be sucked around that o-ring. I would contact Hatz.

Henry

[Henry W]

Here is a manual.

This one seems to show more than the one on the Hatz site.

http://www.embmfg.com/File.aspx?id=9e5dd548-bf9b-44ca-aed4-a552da34f29c

Henry

[Henry W]

I found a parts blowup and it clearly shows that oil is sucked in an oil pickup and through a cylinder where the filter slides in. The filter screen is above the oil level so there is a chance the o-ring could be damaged. I will try posting the picture.

Henry

[Henry W]

Here it is,



The filter screen item# 35 has an o-ring which is item# 36 shown in the picture is the one that could be of concern. As I mentioned before, it would be a good idea to check it out.

Henry

[mike90045]

The oil strainer has 2 O-rings, one at each end.  Both are good.   It's so cold, I'm guessing the oil is being whipped like butter.  The oil warning comes on as soon as the engine shuts off, so there is pressure in the pump.  I'm gong to wait for the day to warm a bit, run the engine till warm (5 min), and then check the oil, and see if the foam is reduced.  My test early this AM, was with the level just above the ADD mark, suctioned the oil out to pull the strainer, re-installed the strainer, and added oil back till just below the FULL mark.

[Henry W]

That is correct. The smaller o-ring is not much of a concern as the larger one. The smaller one is encapsulated in the tube and if it ever did leak some oil would bypass the filter screen. That is not much of a problem.

How cold is it? You might want to switch to Shell Rotella 10w-30 or a good group 4 Synthetic 5w-30 diesel rated oil.

I normally don't recommend oil but I used one Amsoil product in cold weather and had good results with it. Here is the link. http://www.amsoil.com/lit/databulletins/g27.pdf   This 10w-30/SAE30 rated oil worked well in all my Kubota tractors.

Henry