On a stock Twin Cam softtail oil tank is there a check valve in the line to keep oil from gravity feeding to the engine? I know the Evo had a check valve in the pump but the Twin Cam doesn't that I know of. What keeps the oil from draining to the engine? We are having this problem on a custom chopper with an aftermarket oil tank yet we don't have any problem with a stock tank on a different bike. Anybody know what we're missing? I ride a Road Glide and am not familiar with the softtail. Just trying to help out a friend.

 

There's a checkvalve in the engine .Check the line routing in the oil tank as they may not be going to the correct location on the engine.
Ron

 

The oil tank manufacturer was called and he has all the lines correct. I looked in my Road Glide book and there is no check valve per se in the engine. There is the oil pressure valve in the cam plate but that's just for regulating max oil pressure. The only thing I could find is that the piston cooling injectors have an internal check valve that opens above 12-15 psi and closes below to keep from over oiling. If these check valves were damaged or the o-ring around them was damaged then this might be the problem. He is using a custom oil filter that may not have the flapper valve in it and that would allow oil to get to the injectors via gravity. I think we're going to try a stock oil filter that should not allow oil to drain past it and see if that helps. Thanks for the reply!

 

You are correct in the pressure relief valve and the best I can come up with is too much clearance in the pump or possibly the lack of an ADV in the filter. Strangley enough I checked mine the other day that's been sitting since December and it's still close to the full mark on the stick. You would think that over that amount of time oil would have leak down some , even with a tight pump and correct filter?
Ron