[Fatbob-01]

My 2009 Fatbob is making oil, any ideas what can cause this?

[PeterHD13]

If your oil level goes up after the bike runs for a while it could be expansion of the oil due to heat. But if your bike is a dry sump like my 1990 FLTCU the models before the twin cams it might be that oil is being scavenged from the sump by the scavenge pump as the bike warms up or runs. There was a oil check ball valve in Harley oil pumps that is supposed to stop oil running back down into the sump when the engine stops but sometimes it leaks. Weak spring or dirty ball/seat. SO you should check the oil once the bike is warm before adding anymore. I check mine cold then check it again when it's warmed up.

The ball /spring, Oil Pressure release valve/spring and Hydraulic filter screen are located at the oil pump under those flat nose screw plugs. Your suppose to clean them every now and then. The Hydraulic tappet screen is metal I just clean it in some fuel /kero blow dry and put back in. If it becomes blocked your hydraulics and valves won't get any oil.

It's really important that you make sure the Oil pressure release valve slides up and down the shaft it sits in. Stuck open oil goes to the sump, stuck closed the pressure can blow gaskets. I just take out the spring and use and allen key shaft or phillips head screw driver to sit inside the valve body its like a cylinder with one end cut off. Press on the inside and lift it out. Sometimes I found it a bit stuck but it comes out . Smear new oil over it once clean and put it back in.

The ball/spring is the same but you can get it with a small auto magnetic pick up. You'll notice oil coming out when you remove these I do them one at a time. Easy Riders Tech tips said that sometimes the seat the ball sits on is rough allowing gaps for the oil to run back into the sump so they got a ball welded it to a bit of straight rod and put some valve paste on the end of the ball and spun the ball by hand like starting a fire with a stick , a bit to make sure the seat was smooth but you'd need to remove the oil pump so you could clean the paste away I suppose.

You might replace the springs on the ball and oil pressure release valve if your worried there weak, from the HD shop I can't find a measurement in the manual.

Another way oil can accumulate in the sump is a condition known as Wet Sumping. You'll also notice smoke coming out of the exhaust. Pressure seal is lost in the Dry sump system of the Harley by a leak. One cause that happened to me was the Timing plug on the Primary side came loose! Also I then eventually noticed that the O ring on the timing plug was perished. You need to be careful when tightening the plug as the rubber Oring rips easy even with an oil smear on it . I reckon a neoprene one would be better like on the gearbox filler plug. But can't get one yet. So I used a couple of drops of 222 loctitie on the thread and then painted the outside black again . It's OK now but it's something you don't think of, the symptoms can be misinterpreted as worn rings or valve guides and caps. Any way up came all the oil from the sump once the timing plug was sealed properly.

The Primary engine seal and cam seal can blow too.

[Fatbob-01]

Hey PeterHD, thanks that's useful info and I'll check it out on my bike. Ride safe