I should mention that there are seals on the prop shaft also. When you pressure test you can spray a little soapy water on the shaft to look for leaks but that again test oil leaks out of the LU. It won't tell you if the seal for water into the LU is good. That is tested with vacuum but will also show up as milky looking oil when you drain the LU.
Is this a concern?
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I was referring to shift shaft seal and both drive shaft seals. print from SIM shows i believe with both drive shaft seal with lip up and shift shaft seal lip down...is that correct??
I may have misspoken. Actually I guess I did. You are correct. Based on the Yamaha parts catalog for that motor, lip up for driveshaft and lip down for shift. What really surprised me was that the diagram shows both prop shaft seals in the same direction. That I didn't expect.. So I was wrong twice in the same post!
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What gets me is that my prop shaft seals are installed back to back and that arrangement makes perfect sense to me so I ASS U ME D that it made sense always. My lesson learned is to do more research before jumping to a conclusion.
Good luck with your repairs!
Good luck with your repairs!
Omc and mercury install their prop shaft and driveshaft seals spring inside for the first seal and spring out for the second seal. Maybe that is why Omc and mercury pressure test at 12 to 15 pounds and Yamaha pressure test is 3 to 5 pounds.
That's an interesting piece of information. I will take alook at some of my manuals since I have both Mercs and Yamis.
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Yes. Yamaha is 5 psi for lower. The shift seal has a habit of popping out under any more than that. That is why I glue them in with the 847. Also the seal lips are both spring up so they can’t hold as much as Omc n Merc. I spray the seals with soapy water like seasick had stated in a previous post. Works well.
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The holding pressure for the Yamaha F250 for 2005-6 lower unit is 10 psi per the service manual I have. (6P2-28197-1H-11)
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My yammy is a 2002 f225 tura . Thanks everyone for the replies. Great community here . Appreciate y’all
I pressure test units at 5 lbs if they have any used seals in them such as prop shaft seals. If they are all new seals then we test them around 7 to 9 lbs. a good used seal has a chance of blowing out over 5 lbs. if there are any leaks, they will show up at 5.
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Seals can leak in two directions. A pressure test shows if the internal fluids (oil) leaks out. The vacuum test checks if the unit leaks from the outside on, as would be the case with water getting into the lower unit. Both kinds of leaks are possible but most folks check for water in the oil. Other than draining and looking for milky colored oil, the only way to test is doing a vacuum test. In that test you don't see bubbles using soapy water. You create a vacuum using the proper tool and see if the vacuum holds for a period of time like 15 minutes. I use a MightyVac which is a tool made for bleeding brakes. I use it because I have it
99 times out of 100, you are good with a successful pressure test. I have a radiator pressure tester with an adapter for the lower unit. You can make an adapter using a fitting off of a lower unit oil pump.
I have a radiator pressure tester with an adapter for the lower unit. You can make an adapter using a fitting off of a lower unit oil pump.