johnsw
Well-known member
2004 Yamaha 150TXRC 2-stroke
Here's an odd one. What keeps the oil in the engine tank from
flowing back to the sub-tank in the bilge when the engine is
tilted up out of the water? I thought I had an electrical
problem, but after checking everything out and working as
it should, this is where I'm at.
I've got an intermittent low oil alarm problem that I've linked
to the engine tank draining back overnight. If I fill the engine
tank using the emergency switch to the top level line, tilt the
motor up and check it in a few hours, the level is reduced to
just about the low level line. If I clamp the oil line at the sub
tank and do the same thing, it stays full. Definitely back flowing
due to gravity feed, siphoning oil from the engine tank in the
process. No leaks in the bilge or motor.
If I just jump in the boat and go, 5 - 10 minutes out my low
oil alarm sounds and the engine goes into failsafe mode, as it
should. Fill the tank with the emergency switch, and I'm good
for the rest of the day.
My startup routine is now to prime the system with the emergency
switch and fill the tank before starting the engine.
Checking the oil lines and diagrams in the service manual, there
doesn't seem to be a check valve in any part of the system. The
oil transfer pump (which I replaced) doesn't have any internal
valves. I took my old one apart to check it out, so I know that
is the case. Any ideas or suggestions?
John S.
Here's an odd one. What keeps the oil in the engine tank from
flowing back to the sub-tank in the bilge when the engine is
tilted up out of the water? I thought I had an electrical
problem, but after checking everything out and working as
it should, this is where I'm at.
I've got an intermittent low oil alarm problem that I've linked
to the engine tank draining back overnight. If I fill the engine
tank using the emergency switch to the top level line, tilt the
motor up and check it in a few hours, the level is reduced to
just about the low level line. If I clamp the oil line at the sub
tank and do the same thing, it stays full. Definitely back flowing
due to gravity feed, siphoning oil from the engine tank in the
process. No leaks in the bilge or motor.
If I just jump in the boat and go, 5 - 10 minutes out my low
oil alarm sounds and the engine goes into failsafe mode, as it
should. Fill the tank with the emergency switch, and I'm good
for the rest of the day.
My startup routine is now to prime the system with the emergency
switch and fill the tank before starting the engine.
Checking the oil lines and diagrams in the service manual, there
doesn't seem to be a check valve in any part of the system. The
oil transfer pump (which I replaced) doesn't have any internal
valves. I took my old one apart to check it out, so I know that
is the case. Any ideas or suggestions?
John S.