2002 150dxtlra ox66 recirculation valves and oil running down drive shaft

[captainj]

I was changing water pump when lower unit was pulled 2 stroke oil running down drive shaft to the water pump. Checked the recirculation check valves all six not checking. Removed them and they seem to be missing the ball or disk that would block the hole in the valve.
Would the recirculation check valves not working cause the crankcase to load up with oil and cause the lower crankcase seals to fail?
I ordered the check valves. I guess I need to go ahead pull the powerhead to replaced the oil seals if they are leaking. Probably will leak now even after replacing check valves if that is the problem.
I have a yamaha manual it does not have anything about the check valves or how the recirculation system works. Does anybody understand how the system works? When I was looking at the parts schematic it also showed a check valve internal maybe at crankshaft main bearing. What does the internal check valves do. Thanks

[cpostis]

I was looking at the parts diagram for model, "DX150TRLA", you say you have. 2002 DX150TLRA Yamaha Outboard OIL PUMP Diagram and Parts
This model has one check valve after the oil manifold, Item # 13 on the diagram.
Now model Z150TRLA has 6 check valves, part # 15 in this link. 2002 Z150TLRA Yamaha Outboard OIL PUMP Diagram and Parts This is an HPDI motor. Carbureted motors this year and HP have six check valves as well.

Is there a chance the powerhead was replaced? Can you double check your model? A DX150TRLA is a dual prop, fuel injected motor. An Z is a HPDI Motor with a drive belt for the high pressure fuel pump. Of course, a carbureted motor has carburetors.

The other check valves you mention in the block are really relief valves to keep from over pressurizing oil to the bearings.

Now, to replace the upper and lower crankshaft seals, you have to separate the block and crankcase.

Confirm your model/year and let us know what you find.

[captainj]

The model is correct. It is a dual prop fuel injected engine.
The check valves that I was talking about are pressed into the side of the crankcase cylinders for oil recirculation system. They are under Cylinder Crankcase 1 item #7.

[99yam40]

when i took my C40 apart I found 3 of the 4 check valves bad9Nothing in them.
I replace all 4 and tok the one apart that did work to see what it was made of.
there was a small plastic disc in it(no ball).
I guess the plastic gets sucked out or blown out if there is a lean sneeze, or just deteriorates and comes out.

Make sure there are just one check valve on each of the hoses(only one end)

I would replace the lower oil seal also.

I had the same oil leaking down the drive shaft, but I had main bearings that were rust pitted also so I replaced the crank and all seals

[rodbolt17]

no they are not item 7.
item 7 is the check valves that move oil through the main bearings.
the recirc check valves,6 of them, are pressed into the side of the block.
it is not uncommon for some oil to be on the drive shaft.

if you wish to replace the seals it is not nessasary to crack open the block.
it will be nessasary to remove the flywheel,stator and powerhead.
remember this motor lubricates by mixing the oil in the VST then spraying the fuel/oil into the reeds at the intake manifold.

[captainj]

I pullled the powerhead and removed the lower oil seal housing and there was about 1-1/2 ounces of oil in the seal housing.
Is this normal? If not could it be due to the recirculation valves not working, causing the oil to pool there? Are could it be the #7 check valve for the main bearings? Rodbolt what do think?
Thanks to all?

[rodbolt17]

any unused anything is going to puddle at the bottom.
pull the oil pump and let it hang over a drip pan.
see if the oil pump shaft seal is leaking.