Oil coming out fuel pump

[Gord Baker]

Thanks for reading. I have a JD LA105 with a 19.5 single cylinder OHV. Replaced the head gasket, common cause, the mower starts and runs great but after a minute or two it starts bleeding oil out the fuel pump and breather tube. Wispy smoke when I pull the dip stick too. I adjusted the valves after the head gasket, took the fly wheel off and checked the valve which looked fine but there was no hole for oil to return to the crankcase. I am hesitant to tear it down for rings because it runs great otherwise. The mower has 180hrs. Anything else that can build pressure like that? Oil is slightly low from having come out and no fuel smell

Sounds like broken rings or scored cylinder. Try blowing air back into the Crankcase from the Fuel pump pulse line with dipstick out. Plugged vent?

 

[kjonxx]

Possible cracked head or broken rings?

 

[RevB]

The fuel "pump" is a crankcase pressure driven diaphragm pump. The diaphragm is torn and oil is making it's way past.

 

[StarTech]

The fuel "pump" is a crankcase pressure driven diaphragm pump. The diaphragm is torn and oil is making it's way past.

If you referring the Briggs hockey puck vacuum fuel pump you are wrong. The vacuum side is not sealed, it has a restrictive vent but does allowing air in and out thru this vent; therefore, if oil is present it can can be pushed out during excessive pressure impulses.

Now if the diaphragm is torn or damage fuel would be leaking out.

 

[VegetiveSteam]

What do you mean when you say you checked the breather valve? What were you looking for? What did you find? I guess what I'm asking is, how do you know the breather valve is good?

What if you leave the hose off when it blows off? Does oil still come out of the fuel pump with that hose off? Blown head gasket or not, if the breather is working properly, there should not be a build up of crank case pressure. The breather valve should only let air and gases out of the crankcase and let nothing in.

 

[Olrecker]

I was looking for something broken or bent. It seemed fine but at the time I had oil blowing into the intake. That doesn’t seem to be the case after sanding the head but I only say that because it wasn’t smoking after the test cut I did afterwards. Before it would start smoking and bogging down after 50-75 feet depending on the incline. Before sanding the head is was blowing oil out of the breather tube and out the fuel pump. I haven’t done the longer mow with it yet to see if the fuel pump will dissipate further, based on the suggestion here that it maybe just clearing itself out which would be nice but it still has that small cushion of under a minute before its starts leaking. This leads me to believe something is still pressurizing the case. The oddity is that is starts and runs great, usually I experience poor running when these things happen which is why I started the thread because I dont fix them for a living. I would hate to tear it all down so I wanted to do the leakdown test and/or compression test first but the shortening days and personal life are making it difficult

What do you mean when you say you checked the breather valve? What were you looking for? What did you find? I guess what I'm asking is, how do you know the breather valve is good?

What if you leave the hose off when it blows off? Does oil still come out of the fuel pump with that hose off? Blown head gasket or not, if the breather is working properly, there should not be a build up of crank case pressure. The breather valve should only let air and gases out of the crankcase and let nothing in.